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Why cats sleep all day?

Why do cats sleep all day?

Famous American poet Rodney Mckuen once said “cats have it all; admiration, an endless sleep, and company only when they want it”. If you have a cat (or more), it’s probably not that hard to relate to these lines. Cats receive a lot of praise only for being cute, and they’re always quick to enjoy a nice (and often lengthy) nap. But why do cats sleep so much? Turns out, there’s a good reason for that.

Image credits: Jacalyn Beales/Unsplash

If you think cats are sleep addicts, that’s not exactly true. Similar to jaguars, ocelots, and some other members of their feline family, cats are actually crepuscular beings — they’re most active between sunset and sunrise (around twilight). The reason is that their prey is often crepuscular — so if you’re a cat and want to hunt something, that’s a good time to go about it. Many years ago (before we started domesticating them), when both cats and their prey lived in the wild, cats had to stay awake and hunt between dusk and dawn in search of food. 

Hunting could be a very energy-demanding process for any animal, and cats can cover impressive ranges in their search for food. So in order to recharge themselves for the next hunt, cats have developed a habit of sleeping a lot during the day — after all, it doesn’t make much sense to spend extra energy. So evolution pushed cats to sleep so much, and particularly during the day, when humans tend to be most active.

Domestication of these furry animals by humans has certainly brought some changes in their behavior and lifestyle and nowadays, house cats at least don’t roam the wild during the night looking for mice and rabbits — but their sleep-wake cycle has remained largely unchanged. This is the big reason why, for cats, daytime (when we regularly interact with them) is for resting, and resting is serious business.

How much sleep is enough for my cat?

Cats usually require around 15 hours of sleep in a day, but this can vary. Kittens and aging cats tend to sleep more, even up to 20 hours. Active cats may sleep as little as 12 hours. Most of the time cats go through a slow-wave sleep (SWP), light sleep, or a catnap during which their nose and ears are in alert mode and they are sleeping in such a posture that they can evade instantly as soon as they sense any danger. A catnap usually lasts between 15 to 30 minutes.

At least 12-14 hours of sleep is required for cats and both REM and light sleep are important for their health because good sleep ensures better energy conservation, muscle repair, good immunity, and the overall well-being of cats. The diet of cats mostly consists of protein (meat, fish, milk, etc) so proper sleep is also needed for complete digestion of their protein intake. 

However, as far as sleep timing is concerned there is no fixed time at which all cats prefer to go to sleep in the day. Cats have the ability to set their sleeping hours as per their feeding pattern, and one research also reveals that some cats adjust their sleep timing as per the activity of their owners.

What do cats dream about?  

Image credits: Gokul Barman/pexels

Only 25% of a cat’s total sleep is deep sleep and this is the time during which your cat may go through REM (rapid eye movement) sleep, a unique sleeping phase accompanied with dreams (yes, cats can also dream) and involves increased brain activity, it is also experienced by humans and birds. If your cat’s limbs are twitching or whiskers are showing a slight regular movement during her sleep, it is possible that she might be dreaming. Maybe dreaming about you… but probably not — research suggests they’re likely dreaming about being on the hunt.

However, there’s still a chance that your cat may be dreaming about you from time to time. Professor Dr. Nicholas Dodman from Cumming Vet School, New England told Metro in an interview that cats exhibit many of the physiological and behavioral characteristics that humans also manifest in their dreaming. It’s entirely possible, according to a report, that cats dream of a variety of things, from their prey to other cats to their owner petting them. 

Why cats sleep more when it’s raining?

Factors like weather and temperature also affect a cat’s activity and sleeping pattern, and it has been found that on rainy and cold days, cats spent more time sleeping. If you are a cat owner, you may have noticed your cat often lying near the heating system in winters. This is because cats are warm-blooded animals like us which means that on a cold day they require more energy to keep their internal body temperature balanced.

Also, cats, in general, prefer sunny weather and don’t like the rainy season. Cats and water are rarely good friends, and there’s a good reason for this too: it’s hard for them to stay warm during the wet season, and they also hate the noise that comes from the clouds. Plus, if they do get wet, it’s very hard to dry out and the moisture on their skin and fur can easily make them catch a cold.

Cats also tend to sleep more when they feel safe, and tend to pick sleeping spaces where they feel nothing can disturb them. But more sleep is not always a good sign. If your normal-aged cat is sleeping more than 15-16 hours a day, it is possible that she could be suffering from boredom, physical pain, hyperthyroidism, depression, etc. These disorders occur more frequently in cats that are overweight and you should consult a vet if you notice a sudden change in the sleeping habits of your cat or if it sleeps excessively. Just like humans, cats’ sleep patterns can offer hints about their health.

Just like a good night’s sleep is important for the proper functioning of our body, a good day’s sleep is necessary for a cat’s well-being. So the next time your cat is yawning in front of you as you work, don’t call them lazy. They just have a different sleep setting than yours — and arguably a better one.

Who invented school?

School is an institution that is hated (especially during exams) by millions of kids around the world — but at the same time billions of adults remember it as the ‘good old days’. For all its good and bad, society as we know it couldn’t exist without schools — and we’re not just talking about the building, we’re talking about the entire system and environment that allows us to pass knowledge to younger generations and prepare them for what’s to come in the real world (at least in theory). But who actually invented school?

Image credits: Max Fischer/pexels

From old school to modern schooling system

Ironically enough, for all the information you can find in schools, no textbook mentions exactly when and how the idea of a school originated. This is mostly because it depends on how exactly you define a school. For instance, in ancient Greece, education was somewhat democratized, and education in a gymnasium school was considered essential for participation in Greek culture, but it was reserved only for boys (and often, not all boys). In ancient Rome, rich children were tutored by private professors, but neither of these is a school in the sense we consider today — public, formal education that is compulsory, open, and available to all — though you could argue that in some sense, school dates from ancient times, and the organized practice of teaching children dates for thousands of years.

Compulsory education was also not an unheard-of concept in ancient times –though it was mostly compulsory for those tied to royal, religious, or military organizations. In fact, Plato’s landmark The Republic, written more than 2,300 years ago, argues in favor of compulsory education, though women and slaves were not truly a part of Greek society.

Much information about schooling is also lost to the shroud of time. For instance, there is some indirect evidence about schools in China existing at least 3,000 years ago, but this comes from “oracle bones” where parents would try to divine whether it was auspicious for their children to go to ‘school’ — and there’s little information about what these schools were like.

It’s not just the Chinese, Greeks, and Romans. The Hindus, for instance, had developed their own schooling system in the form of gurukuls. In 425 AD, the Byzantine empire in Rome came up with the world’s first known primary education system dedicated to educating soldiers enrolled in the Byzantine army so that no person in the army faces problems in communicating and understanding war manuals. Different parts of the world had developed different types of education — some more efficient than others.

In Western Europe (and England, in particular), the church became involved in public education early on, and a significant number of church schools were founded in the Early Middle Ages. The oldest still operating (and continuously operating school) is The King’s School in Canterbury, which dates from the year 597. Several other schools still in operation were founded in the 6th century — though again, you could argue whether they were true schools as they were only open to boys.

Albert Bettannier’s 1887 painting that depicts the scene of an old European school. Image credits: Deutsches Historisches Museum Berlin/Wikimedia Commons

Furthermore, compared to the modern schools, education in the above-mentioned institutes was more focused on religious teachings, language, and low-level or practical skills only. Many of them even used to operate in a single room with no set standards and curriculum, but as humanity progressed ahead people started to realize the need for an organized system to educate the future generations. 

For more than ten centuries, schools maintained the same general profile, focused mostly on a niched set of skills and religious training. In the 9th century, the first university was founded in Fez, Morocco. However, that too was founded as a mosque and focused on religious teachings. The oldest university still in operation, the University of Bologna, in Italy, was founded in 1088. It hired scholars from the city’s pre-existing educational facilities and gave lectures in informal schools called scholae. In addition to religion, the university also taught liberal arts, notarial law, and scrivenery (official writing). The university is notable for also teaching civil law.

However, the university is not necessarily the same as a school — it wasn’t a public “for all” education system, but rather a “school” for the intellectual elite. For schools to truly emerge as we know them today, we have to fast forward a few more centuries.

Compulsory, free education for all

In 1592, a German Duchy called Palatine Zweibrücken became the first territory in the world with compulsory education for girls and boys — a remarkable and often-ignored achievement in the history of education. The duchy was followed in 1598 by Strasbourg, then a free city of the Holy Roman Empire and now part of France. Similar attempts emerged a few decades later in Scotland, although this compulsory education was subject to political and social turmoil.

In the United States — or rather, in the colonies that were to later become the United States — three legislative acts enacted in the Massachusetts Bay Colony in 1642, 1647, and 1648 mandated that every town having more than 50 families to hire a teacher, and every town of more than 100 families to establish a school.

Prussia, a prominent German state, implemented a compulsory education system in 1763 by royal decree. The Prussian General School Regulation asked for all young citizens, girls and boys, to be educated from age 5 to age 13-14 and to be provided with a basic education on religion, singing, reading, and writing based on a regulated, state-provided curriculum of textbooks. To support this financially, the teachers (often former soldiers) cultivated silkworms to make a living. In nearby Austria, Empress Maria Theresa introduced mandatory primary education in 1774 — and mandatory, systemized education was starting to take shape in Europe. Schools, as we know them today, were becoming a thing.

Meanwhile, the US was having its own educational revolution.

In 1837, a lawyer and educator Horace Mann became the Secretary of the Massachusetts Board of Education in the newly-formed United States. Mann was a supporter of public schooling and he believed that without a well-educated population political stability and social harmony could not be achieved. So he put forward the idea of a universal public education system for teaching American kids. Mann wanted a system with a set curriculum taught to students in an organized manner by well-trained subject experts. 

Without undervaluing any other human agency, it may be safely affirmed that the Common School…may become the most effective and benignant of all forces of civilization.

Horace Mann, Father of the Common School Movement

Mann employed his “normal school” system in Massachusetts and later other states in the US also started implementing the education reforms that he envisioned. He also managed to convince his colleagues and other modernizers to support his idea of providing government-funded primary education for all. 

Due to his efforts, Massachusetts became the first American state in 1852 to have a mandatory education law, school attendance and elementary education were made compulsory in various states (mandatory education law was enacted in all states of the US by 1917), teacher training programs were launched, and new public schools were being opened in rural areas. 

At the time, when women were not even allowed to attend schools in many parts of the world, Mann advocated the appointment of women as teachers in public schools. Instead of offering religious learning to students, Mann’s normal schools were aimed at teaching them reading, writing, grammar, arithmetic, geography, and history. He believed that school education should not incorporate sectarian instructions, however, for the same reason, some religious leaders and schoolmasters used to criticize Mann for promoting non-sectarian education.

The innovative ideas and reforms introduced by Mann in the 1800s became the foundation of our modern school system. For his valuable contribution in the field of education, historians sometimes credit him as the inventor of the modern school system.

However, as we’ve seen, the history of schools is intricate, complex, and very rich. There is no one “inventor” of school — the process of arriving at the school systems we have today (imperfect as they may be) took thousands of years of progress, which was not always straightforward.

Shocking facts about school education

Now that we’ve looked a bit at the history of the school, let’s see how things are today — and why there’s still plenty of work to be done in schools around the world.

Image credits: Pixabay/pexels
  • A study conducted by the Institute of Education in the UK suggests that quality of primary education is more crucial for an individual’s academic progress, social behavior, and intellectual development as compared to factors including his or her family income, background, and gender. Another study highlights that students who receive good elementary education and have a positive attitude about the significance of their performance in primary and middle school are more likely to earn well and live a better life than others in the future.  
  • A UNESCO report reveals that school education up to nine years of age is compulsory in 155 countries but unfortunately, there are more than 250 million children in the world who are still not able to attend school. 
  • According to International Labour Organization (ILO), due to poverty and lack of educational opportunities, 160 million kids are forced into work across the globe and about 80 million of them work in unhealthy environments. Thousands of such kids are physically and sexually abused, tortured, and are even trained to work under drug mafia, criminal groups, and terrorist organizations. Some studies reveal that child labor is also associated with school dropout in less developed countries. Due to poor financial conditions, many individuals at a young age start giving preference to economic activities and lose interest in costly education opportunities. However, an easily accessible and high-quality school education model that could allow children (from poor families) to pursue education without compromising their financial security can play an important role in eliminating child labor.
  • African nation South Sudan has the lowest literacy rate in the world. Only 8% of females in this country are literate and overall only 27% of its adult population is educated. 98% of the schools that offer elementary education in Sudan do not have an electric power supply and only one-third of such schools have access to safe drinking water. 
  • City Montessori School (CMS) located in Dehradun, India is hailed as the largest school in the world. The CMS campus houses 1,050 classrooms in which more than 50,000 students attend classes every day. 

For Horace Mann, schools were a means to produce good citizens, uphold democratic values and ensure the well-being of society. Though not all schools are able to achieve these goals, the power of school education can be well understood from what famous French poet Victor Hugo once said, “He who opens a school door, closes a prison”.

What is Special Relativity: A Guide to Spacetime, Time Dilation and Length Contraction

Imagine a passenger sat aboard a train. They awake from sleep and see another train moving past at a constant velocity. The passenger is momentarily confused. Which train is moving? Theirs or the one opposite?

In 1905 this idle thought and the concept of relative motion would inspire one of science’s most important theories. Over a series of four papers, Albert Einstein, a patent clerk in Bern, Switzerland, would change physics forever. The theory encapsulated by those papers–special relativity– would reformulate not just the laws of motion, but the relationship between matter and energy, and the very nature of time and space themselves.

Thanks to special relativity what was once immutable and unchanging became an active player in the events of the Universe. Something that Albert Einstein, the theory’s father would only expand upon in the future. But, before that, uniting space and time as one entity–spacetime–would have some remarkable consequences for these previously separate aspects of the Universe and for the mechanics that govern its events.

Spacetime, Inertial Reference Frames, and Relative Motion

Spacetime is filled with events–it would be rather boring if it wasn’t. These events can be as mundane as egg crack on the kitchen floor, to events as powerful and violent as the eruptions of supernovea.

Robert Lea

Within spacetime are inertial reference frames–areas filled with synchronised clocks that allow events to be given coordinates. If one inertial frame exists then an infinite amount exist in relative motion.

In each inertial reference frame is an observer. For the sake of our thought experiments, these will be twin sisters Astra and Terra. One important thing to note, just like in the train analogy which opened our explorations, these observers believe that they are stationary in their frame.

Twin sisters Terra and Astra borrow their father’s sports car to demonstrate this. Terra stands on a bridge as Astra races towards her in her father’s car at a steady velocity of 100mph. Terra will see Astra’s reference frame approaching at this speed and she and the bridge are at rest As far as Astra is concerned, she considers herself and the car at rest, and that it is the bridge that races towards her at 100mph.

This only holds if these frames are inertial–not accelerating or turning which is counted as acceleration in physics. Think about it like this; in the train analogy, the passenger doesn’t know if their train is moving or if it’s the train opposite. If the train was accelerating–the passenger would ‘feel’ this acceleration and thus know which train is moving.

The exclusion of accelerating frames will become important later.

Let’s now explore the consequences of relative motion on how observers measure the events that occur around them.


Years later, Terra and Astra’s father finally ungrounds them both for the destruction of both his car and a local bridge, meaning Terra can escort Astra to the local train station as she embarks on a journey to astronaut training camp. As the train pulls away from the platform and achieves a constant velocity, lightning strikes it at the front and the back, getting Terra–a theoretical physicist–thinking about how she and her twin sister would have experienced the event.

This encapsulates a revolutionary aspect of Einstein’s 1905 theory, the idea that observers in different reference frames experience time and space differently. So much so that observers in different reference frames can disagree on the order in which events occur.

Terra sees event 1-the front of the train struck by lightning, occur at the same time as event 2-the back of the train struck by lightning. Astra, however, sees event 1 occur before event 2.

But what about the law of causality? What is to prevent event A that causes event B being seen after that effect in a particular frame and thus in that reference frame having the consequence of putting effect before cause?

This might not sound like a problem, but say Astra sees B before A, she could potentially send a signal to Terra about B that is received before A has even happened. Maybe quick enough that Terra could actually stop A from occurring?

Terra ponders this as she screams at her more adventurous sister to sit inside the train rather than stand on its roof.

Transformations in Special Relativity

When examining the rules that Einstein would need to transform coordinates from one inertial reference frame to another, the physicist discovered that they were identical to the transformations developed by Dutch physicist Hendrik Lorentz.

Lorentz had arrived at these transformations whilst considering James Clerk Maxwell’s laws of electromagnetism. This finding excited Einstein, as a major reason he began speculating about the nature of light and the speed at which it travels was a result of Maxwell’s laws of electromagnetism. 

These laws didn’t just unite the phenomenon of electricity with magnetism — creating electromagnetism (over the coming decades, physicists will get much more adventurous with nomenclature) — Maxwell found that electromagnetic waves travelled at 3.0 x10 ⁸ m/s — exactly the speed of light.

Thus, Einstein’s predecessor had found that light is an electromagnetic wave.

The use of the Lorentz factor in the transformations of special relativity leads to a stunning consequence. The fact that nothing with mass can travel at the speed of light. But the use of Maxwell’s equations will deliver another, equally impressive aspect to the nature of light and its speed in a vacuum.

The fact that it is absolute.

Absolute C

As well as proving the universe with a speed limit, the speed of light in a vacuum also proves counter-intuitive by taking the same value in all reference frames. Astra and Terra will use a gun and laser pen to demonstrate this phenomenon.

Clearly, if light behaved like any other projectile Astra who is in a reference frame travelling at c/2 would measure the speed of light racing away from her at c, whilst Terra should register it travelling at c + c/2. But, she doesn’t she also registers it as travelling at c.

The reason this should be the case is, Einstein reasoned, that if it were different then if he raced a beam of light at c, he could turn and see that light as a stationary electromagnetic wave, something that is forbidden by Maxwell’s laws of electromagnetism.

It’s the invariance of c and the fact nothing can accelerate beyond it that saves causality and ensures that an effect cannot precede a cause.

(Robert Lea)

Thus, in special relativity, not everything is mutable between reference frames. In fact, the first of two postulates Einstein adopted when thinking about relativity is the fact that the laws of physics should be the same in all inertial reference frames. 

Terra jots down her ideas about how what she has learned from here experiments thus far whilst mulling over the fact her sister runs much faster since being on a train that was struck by lightning.

The Two Postulates of Special Relativity

The idea that light travels at c in a vacuum in all frames to all observers gives Einstein his second postulate for special relativity. The speed of light in a vacuum has the same constant value (3.0 x 108 m/s) in all internal reference frames.

Exploring this second postulate, Terra wonders how is it possible that both she and Astra could register the same value for the speed of light in a vacuum?

Something must be different between the two frames. It turns out that there is a difference and Einstein realised that it has stunning consequences for our concepts of space and time. Or more precisely for Einstien’s united entity, spacetime.

Time Dilation: Physics on Flexitime

In special relativity, it is accepted that ‘moving clocks run slow.’ To put this in a more understandable way, an observer in an inertial reference frame will observe the clock in another inertial reference frame that is in relative motion moving slowly.

The idea that ‘moving clocks run slow’ gave rise to one of science’s most famous thought experiments. The so-called ‘Twin Paradox’. The paradox element of the example arises from the idea that if Terra sees Astra’s clock run slow, and Astra sees Terra’s clock run slow, what happens when the twin sisters meet back up?

Surely Astra will expect Terra to be younger upon her return, whilst Terra will expect Astra to be younger?

To demonstrate this idea Astra will once again embark on a journey in her ship, but this time rather than a short jaunt she will leave for a distant star system, a journey that will separate the twins for many years.

The answer to this paradox lies in the fact that special relativity works only in non-inertial frames–that is frames that aren’t accelerating. Whilst Terra’s frame remains in constant motion, it’s clear that Astra’s frame MUST accelerate at points. For example, Astra has to turn her ship around to return to earth, that means that even if she manages to do so with slowing down (deceleration also counts as acceleration in physics) circular motion is acceleration too!

A practical demonstration of the effect described in the twin paradox thought experiment can be seen in particle accelerators. As particles that decay in incredibly short lengths of time are accelerated to speeds approaching that of light researchers can measure them lasting for longer than they should. Of course, if a scientist could race alongside the hurtling particle this scientist would measure it decaying in the usual amount of time.

There’s another factor to special relativity that affects that can be seen with short-lived particles.

Muons are short-lived particles that are created in Earth’s upper atmosphere when it is struck with cosmic rays, that exist for 2.2 microseconds. Even when factoring in time dilation and the incredible velocity of muons–0.98c or 98% the speed of light–very few of these particles should survive long enough to strike the surface of our planet. And yet far too many do just this.

Something else must be working to enable the muons to reach the ground. What if, as well as granting them extended time special relativity could also shorten the distance that the electron-like particles have to cover?

Length Contraction: Short on Space

Possibly an even more counterintuitive idea than time dilation is length contraction–or Lorentz contraction. Whilst time can sometimes seem to us like an abstract concept (who hasn’t experienced the seemingly stretched time of a workday or a school day?) length–distance–is something we can see and measure quite easily. The idea that you could take a solid iron rod and measure it to have different lengths depending on the speed at which it moves and whether you are moving with it or not sounds absurd.

But it’s correct.

Of course, like time dilation we don’t see these effects in everyday life as the velocities required to cause length contraction are close to the speed of light in a vacuum. Fortunately, Astra and Terra are on hand to demonstrate again as its time to put the rocket ship away. In their attempt to park Astra’s ship in Terra’s barn they discover another paradox.

Clearly that from the perspective of Terram, the ship will fit in the barn, albeit briefly. Astra disagrees.

So what is the solution?

Obviously, the ship isn’t going to fit when it is stationary, but the sisters want to know if there is a point when the whole ship will be inside the barn. Fortunately, the barn also has back gates so they can run the experiment without too much damage.

The key to solving this paradox is simultaneity. Because events can occur in different orders for observers in different reference frames, it’s quite possible for Terra and Astra to disagree whether the rocket was ever fully inside that barn.

This is the spatial equivalent of the twin paradox and the answer to the question ‘which sister is correct’ in both cases is the same: both.

What both of these effects tell us is that in special relativity there is no reference frame that has ‘privilege’ over another.

But There’s More…

Thus far we’ve focused our discussion on how Einstein’s theory of special relativity affected how we think about the world, but in terms of changing the world, no element of this theory had as much impact as the matter/energy equivalence. It was this concept and E=mc2 the equation that embodies it, that would give rise to the atom bomb and the mushroom cloud that is etched in our minds as the ultimate symbol of destruction.

It is cruelly ironic that a lifelong pacifist like Einstein will forever be linked with man’s most destructive impulses.

But, as the sun sets over the shattered doors of Terra’s barn, Astra suggests to her now elderly twin that this is a discussion for another day.

Sources and Further Reading

Lambourne. R. J., ‘Relativity, Gravitation and Cosmology,’ Cambridge University Press, [2010].

Cheng. T-P., ‘Relativity, Gravitation and Cosmology,’ Oxford University Press, [2005].

Fischer. K., ‘Relativity for Everyone,’ Springer, [2015].

Takeuchi. T., ‘An Illustrated Guide to Relativity,’ Cambridge University Press, [2010].

Like a moth to the flame: why moths are attracted to light

In the summer, if you keep your light on and window open you are almost guaranteed to get some fluttering visitors. Moths, in particular, are notorious for being attracted to light, but what lures them in? Surprisingly, the exact reason as to why moths are attracted to light has not been definitively answered and there are not a lot of hard facts. However, there are a number of theories as to why moths are “drawn to the flame”.

Guided by the moon

The most prominent theory is that of transverse orientation. In simpler words, the moths may keep a fixed angle with the moon and the stars to orient themselves so that they fly in a straight line. This is a similar technique to humans using the North Star to navigate. However, this strategy only works when the light source is very far away. An artificial light seems brighter than the moon and could be mistaken for it. However, it is not far enough away to navigate by, which results in a spiral towards the light as the moth tries to keep a constant reference to it.

While light from the moon and stars is seen parallel by insects, light from a lamp radiates all around — and this can cause some obvious problems. First and foremost, moths will find themselves circling the light source in endless loops as they attempt to follow the light on one hand, while feeling the need to escape wind plume disturbances, on the other hand.

Because most flying animals tend to keep the lit sky above them so they don’t fly upside down, lamp-attracted insects will tend to dip down when closing in on an artificial light source that they may confuse with the skylight. This propensity is exploited by moth traps, which are designed to be placed around lamps at just the right distance to catch spiraling moths and send them down a collecting funnel into the trap.

Moths evolved when the strongest lights were emitted by celestial bodies so it could make sense that they don’t know how to deal with artificial light. However, it has not been proven that moths actually use transverse orientation to navigate, and if they did it would probably be just the migratory species using it, not the vast majority of small moths.

Researchers use light cones to attract moths in order to study them. Image credits: Bernard Dupont.

Sexy flames

In the 1970s, the entomologist Philip Callahan, who worked for the U.S. Department of Agriculture, discovered that lit candles emit an infrared light spectrum that is the same frequency as a female moth pheromone (he also discovered that these pheromones glow). So basically, the male moths would think that the flame is a female and die trying to mate with the flame. However, moths are even more attracted to UV than infrared light so this theory would not adequately explain the attraction to light — UV light does not have the same frequency as moth pheromones.

Glowing nectar

However, flower nectar does reflect UV light, and the moths’ visual system allows them to see in the UV range. Since many moths feed on nectar during the night, perhaps they are attracted to light because it could reveal a meal? Alas, moths use other ways to find food, such as detecting high levels of CO2 from the flower that can inform a moth about the presence of nectar in a flower.

In contrast

A final theory is that moths are confused because they actually want to reach the darkest point next to the light. The reason for this is that contrast makes a color difference look the sharpest due to “Mach bands”. So, next to a bright light, the dark spot nearby looks even darker. Dr. Henry Hsiao published in 1973 that moths in his experiments did not spiral into or fly directly at a light source, but instead flew into the region next to the lamps. It could be that they see a darker area next to the lamp due to the high contrast and fly there to try to escape the light.

Mach bands, as perceived by the human eye. Image credits: DancingPhilosopher.

Once they have reached a light, the moths might stay close to it for two reasons. Firstly, they may have tired themselves out and need to rest. Secondly, the brightness of the light might spark them to respond as they do to sunlight, which is to hide or become inactive.

Although we don’t know very much about why moths are attracted to light, we do know how far this attraction works. If you have a light on your porch on, you will attract moths that are up to 23 meters away. At least that is what Franz Hölker and his research group discovered in their experiments in one of Germany’s darkest areas in Westhavelland (known as an international “dark sky reserve”, also a haven for stargazers), 70 kilometers north west from Berlin. They found light to act like a vacuum cleaner in bringing all the moths in this radius to the light.

Artificial lighting can cause moths, and other insects, to waste time and energy. This can be particularly problematic for migrating species, for which timing is of the utmost importance. It can also lead to the insect’s death, by exhausting its energy reserves, being killed by humans, or by the heat of the light source.

Somehow light confuses moths, though it is unclear exactly why. Most of the research on this matter is older, and new technology would surely help to shed light on this question. Hopefully, researchers will renew this interest in this question to help settle it once and for all.

What an asshole. Credit: Wikimedia Commons

Why mosquitoes bite me more than others

What an asshole. Credit: Wikimedia Commons

What an asshole. Credit: Wikimedia Commons

I’ve been engaged in an epic battle with mosquitoes for as long as I can remember. While every other kid was looking forward to summer, I could only shiver at the inevitable blisters my arms and legs would suffer.

My grandmother used to tell me I have “sweet blood”, which was very convenient for these tiny vampires. I cut candy out of my diet, but I still got bitten. Okay, so sweet blood is bullshit. But that still didn’t change the fact that I was targeted far more often than other people. Then I realized I wasn’t alone — apparently, I’m part of a select group of people listed on the mosquito’s menu as a delicacy. Dammit! What’s your beef with us, you freakin’ vampires?

Well, luckily I grew up to become a science writer. My forays confirm that mosquitoes are attracted to some people more than others. As to why, the jury isn’t out yet — there is a combination of factors that make me look like a light bulb for these bloodsuckers. The fact that there are over 3,500 species of mosquitoes, some varying in dietary choices more than others, doesn’t help, either.

[panel style=”panel-info” title=”Why mosquitoes want to suck your blood” footer=””]First of all, it’s only the female mosquito that bites hosts. The benign males munch on flower nectar instead.

Female mosquitoes feed on blood, but not for their own nutritional purposes. After piercing the skin with its mouthpart, the hypodermic needle-like proboscis, the female mosquito starts sucking the blood out and into its abdomen. It is here that the blood is digested to produce eggs. They need the protein and other components in the blood to produce their eggs. [/panel]

In the United States, some 175 mosquito species have been identified, the most common of which are Anopheles quadrimaculatus, Culex pipiens, Aedes aegypti and Aedes albopictus. So, research that involves these mosquito species should be the most relevant.

First, we should start with what we know for sure: mosquitos, the females specifically, identify targets by sensing carbon dioxide. Why CO2? Because all vertebrates produce it, so mosquitos found that being able to detect this chemical marker offered them an evolutionary advantage. Using their maxillary palp organ, mosquitos can ‘sniff’ carbon dioxide from as far as 150 ft (40m).

Right off the bat, this explains why mosquitos will come after you more frequently and in greater numbers when you’re exercising outside: you’re breathing harder and releasing more carbon dioxide than usual. Overweight individuals will also release more carbon dioxide because their bodies need more oxygen. Generally speaking, the higher your metabolic rate, the easier it will be for mosquitos to find you. This also serves to explain why pregnant women or people who drink alcohol attract more of the winged villains. For the same reason, adults are more prone to mosquitos than children, as are men more than women.

Of course, mosquitos rely on other cues as well besides carbon dioxide since living, blood-flowing vertebrates aren’t the only ones producing this gas (for example, mosquitos don’t attack trees). So to navigate and find a worthy host, mosquitoes also make use of visual markers. For instance, dark clothing is more attractive to the mosquitoes than the lighter kind. Besides coloring, mosquitos also use motion detection, so if you’re moving around an otherwise stationary environment you’re a sitting duck.

Another marker is body heat. While CO2 tells the mosquito how to find you, your warmest parts of the body, which are also the most vascularized, tell the annoying critters where to bite. The most vulnerable body parts are the neck, inner elbow, backs of knees, armpits, and wrists.

There’s also evidence that suggests mosquitoes are attracted to certain smells. Among their favorites are lactic acid, ammonia, uric acid, carboxylic acid, and octenol (however, they seem to hate the smell of chickens). These compounds can be found in the sweat and breath. A 2011 study also found a few types of bacteria made skin more appealing to mosquitoes. The ankles and feet host the most robust bacterial colonies, which might explain why these are so prone to biting.

Finally, my grandma was half-right. Mosquitoes seem to be attracted to certain blood types more than others. Studies suggest Type O individuals are the tastiest. But ultimately, what makes some stand out more than others in the face of mosquitoes is governed by genetics. Joe Conlon, PhD, technical advisor to the American Mosquito Control Association, says genetics account for a whopping 85% of our susceptibility to mosquito bites.

3D meteorite level.

What’s the difference between an asteroid and a meteorite?

On June 30th, 1908, the boreal forests of Tunguska, Siberia, were shaken (and subsequently flattened) by a massive explosion. It wasn’t man-made — an asteroid pierced our planet’s atmosphere and exploded before hitting the surface.

3D meteorite level.

Artistic rendering of a meteorite.
Image via Pixabay.

This explosion, known as the Tunguska event, would make history. It was the largest impact event humanity has ever witnessed first-hand and would lead the UN to declare June 30th the International Asteroid Day.

While definitely awe-inspiring, the event didn’t lead to the massive loss of life that, say, the Chixulub Impactor caused (that’s the pebble that killed the dinosaurs). So why did one space-rock kill off the largest beasts to ever roam the Earth, while another merely flattened 2,000 square kilometres (770 square miles) of forest without causing a single human death? Well, the secret is all in the definition. Today, we’ll take a look at that simple yet oh so important distinction between an asteroid and a meteorite.

What is an asteroid?

The word itself gives us a glimpse into the nature of asteroids. “Aster” is the ancient Greek word for ‘star’, and the suffix “-oid” is used to show an incomplete or imperfect resemblance to the root word. “Asteroid”, therefore, means ‘star-like’ or, taken more literally, ‘star-like, but not quite’.

Keep in mind that for the ancient Greeks looking up into the night sky, planets and stars all looked the same; ‘aster’, therefore, can be understood as both ‘star’ and ‘planet’.

Vega asteroids.

Artist’s concept of an asteroid belt around the star Vega. Oumuamua, the first object to pass through our solar system that was confirmed to come from outside it — originates from this system.
Image credits NASA / JPL-Caltech.

Asteroids are chunks of space rock ranging from one meter to almost a thousand kilometers in diameter. The larger ones may rightfully be considered minor planets (or dwarf planets/planetoids). Ceres is a good example of this latter category, and the largest known asteroid. These large ones closely resemble planets: they’re roughly spherical and have at least partly-differentiated core structures. They’re generally considered baby planets that didn’t quite make it to adult status.

Most asteroids, however, are quite petite. They also don’t seem to prefer a particular shape. To the extent of our knowledge, they either formed from the primordial matter of a stellar system or via subsequent impacts between its first rocky bodies. Most asteroids in our neighborhood today make a home in the asteroid belt (surprising, I know).

So, to recap: asteroids are chunks of rock or metal (or both) in space. They’re mostly made up of telluric elements (such as carbon, metals, and silica), which tend to be quite resilient. They’re either planets that couldn’t grow large enough or their shattered remnants. Most known ones hang out in the asteroid belt between Mars and Jupiter, but they can take on all sorts of orbits (or none at all!)

What is a meteorite?

Hoba meteorite.

The Hoba meteorite in Grootfontein, Namibia, is the largest meteorite known to have landed on Earth. Estimated to weigh around 60 tonnes, it has never been moved from the spot it was discovered in. Hoba is currently a very visited touristic attraction.
Image credits Sergio Conti / Wikimedia.

A meteorite is any space-borne body that enters a planet’s or moon’s atmosphere, survives the violent trek through it, impacts the surface, and leaves behind solid pieces of material. The name comes from the ancient Greek words “meta” and “aerio”, which put together roughly translate to ‘something hanging up in the air’.

Meteorites start their life as meteoroids (small meteors) or asteroids. On contact with an atmosphere, meteorites experience immense friction, causing them to spontaneously combust (at up to 3,000 degrees Fahrenheit, or 1,649 degrees Celsius). These fireballs — colloquially called shooting or falling stars — are meteors.

The life of a meteor is short — and hellish. The friction they experience is enough to raise surface temperatures beyond the material’s boiling point, vaporizing it layer by layer. In fact, it’s enough to break apart its (and the atmosphere’s) constituent molecules into ionized particles (basically plasma), which then recombine, releasing energy as light. This is the tail you see on a shooting star.

Meteor over Sardinia.

Meteor over Sardinia, seen on the 8th of May 2016.
Image credits Migebuff / Wikimedia.

The extreme violence of the final impact generally shaves off much of a meteor’s mass — the remaining kernel is our meteorite. Keep in mind that geologists generally call impactors large enough to create a crater ‘bolides’, while astronomers tend to prefer ‘meteorite’.

Depending on chemical composition, angle and speed of atmospheric entry, as well as sheer happenstance (whether it breaks apart or not), a meteor needs to range in size between a marble and a basketball for even a tiny portion of it to reach our planet’s surface.

Meteorites under 2mm (0.07in) in diameter are called micrometeorites. Meteorites that impact celestial bodies apart from Earth (and thus don’t necessarily pass through an atmospheric layer, such as those hitting the Moon) are called extraterrestrial meteorites.

As a side note, these burning chunks also spawned the associated term ‘meteorology’, or ‘the knowledge of things happening up in the air’, the branch of atmospheric sciences involved heavily in the study and forecasting of weather events.

So… what’s the difference between them?

As a general guideline, most meteorites are asteroids — but very few asteroids are meteorites.


Ceres, for example, is a moon and an asteroid. We do NOT want it to be a meteorite, too!
Image credits NASA / JPL-Caltech / UCLA/ MPS / DLR / IDA.

The definitions tend to overlap a little. Let’s take size, for example. An astronomer will call any of these space projectiles ranging between a molecule and a chunk several hundred feet wide (usually up to 100m / 330ft in diameter) a meteoroid. Anything larger than that, generally, is considered an asteroid.

However, that leaves out chemistry, which is also a hard delineator for what is (and isn’t) an asteroid. Comets are globs of ice and dust formed in the freezing corners of the cosmos (i.e. outside of solar systems). They also have a little pocket of atmosphere around them (a distinctive feature for comets), generated by evaporation from this ice. Their interaction with heat and particles generated by stars is what creates those long, elegant plumes that are quintessentially comet-y.

Comets can and do fly towards planets and moons. The beefier ones also generally make it through any atmospheric layer and impact the surface. What makes comets generally fall short of being termed ‘meteorites’ is that they’re made up of volatile materials that don’t survive post-impact. However, some do — and also leave behind traces of their impact in the form of impact glass or diamonds. While definitely traces of impact, it can be seen as a technicality to consider such elements remnants of the impacting body itself. I personally do. So, following the impact-and-debris definition, I’d consider comets impacting the surface to be meteors as well.

And herein lies the difference. To be a meteorite, one needs to impact a planet or moon and leave behind solid debris. To paraphrase Iain Banks (my favorite author) the meteorite only lives as it is falling. For asteroids, it’s sufficient to be. Have the right chemical make-up, don’t be too tiny, don’t sublime too much when around stars, and voila! You’re an asteroid.

Most asteroids are nice and never impact any planets or moons. The overwhelming majority of them, actually, are content to orbit around in their asteroid belts or on whatever path they’re set on. But we should never take their absence for granted; it only takes one to come visiting for humanity to become a thing of the past.

Just ask the dinosaurs.

The science behind why leaves change color in autumn

Ah, autumn—the air is crisper and the trees are turning brilliant shades of gold, red, and brown. In the temperate areas of the world, it gets very cold in the winter and there is not much sunlight, which the trees need to feed themselves. Leaves are delicate and can’t survive the winter, so the tree prepares itself for the cold by taking all useful things from the leaves before they fall. This preparation process is what causes the leaves to display their striking autumn colors. There’s a good reason why different trees have leaves that turn different colors.

Preparing for winter

In the summer, most trees have green leaves because they contain the pigment chlorophyll. This pigment is also used to convert sunlight into energy for the tree. In summer, chlorophyll is constantly replaced in the leaves. When it gets cold, the plants stop making chlorophyll and it breaks down into smaller pieces. The trees can reuse the nitrogen that is in the chlorophyll molecule. This is why leaves change colors before they fall off of the tree; the important nutrients that can be reused are taken out of the leaf. The time when leaves start changing color is more dependent on light than on temperature so leaves start changing color at about the same time each year. When deciduous trees reach this light threshold, carbohydrates are transferred from the leaf to the branch and no new minerals are brought in. The trees prepare to separate with their leaves. 

A leaf turning red in the fall. The green is residual chlorophyll. Image credits: kvd.

A rainbow of autumn colors

The green color of chlorophyll is so strong that it masks any other pigment. The absence of green in the fall lets the other colors come through. Leaves also contain the pigments called carotenoids; xanthophylls are yellow (such as in corn) and carotenes are orange (like in carrots). Anthocyanins (also found in blueberries, cherries) are pigments that are only produced in the fall when it is bright and cold. Because the trees cut off most contact with their leaves at this point, the trapped sugar in the leaves’ veins promotes the formation of anthocyanins, which are used for plant defense and create reddish colors.

However, trees in the fall aren’t just yellow and red: they are brown, golden bronze, golden yellow, purple-red, light tan, crimson, and orange-red. Different trees have different proportions of these pigments; the amount of chlorophyll left and the proportions of other pigments determine a leaf’s color. A combination of anthocyanin and chlorophyll makes a brown color, while anthocyanins plus carotenoids create orange leaves.

The rainbow of autumn colors. Image credits: Pixabay.

Low temperatures still above the freezing point help to produce anthocyanin, which produces a bright red color. An early frost weakens the color by destroying the creation of anthocyanins, however. Drought can also cause leaves to fall off without changing color. Where just a few tree species dominate, like in New England and Northeast Asia, color displays are intense but short. Diverse forests mean a longer display. Cloudy and warm falls like those in Europe cause dull colors.

Where the stem of the leaf attaches to the tree, a layer of cells forms that eventually cuts the tissue that attaches the leaf to the tree. There is a closed scar on the branch where the leaf was attached; the leaf is then free to fall when prompted by wind, gravity, rain, and so on. When the leaves die and the chloroplasts are completely broken down, leaves turn a boring brown.

And that is the science behind why the leaves that fall in the autumn are everything from red and yellow to orange and bronze to, finally, brown.


Why you shouldn’t pop your pimples — Really, you shouldn’t

Credit: Pixabay.

Popping pimples can be very tempting, but this is considered a bad idea by most dermatologists. Picking at your blemishes can spread infection and ultimately worsen your acne. It can also permanently scar your face. If you do insist on getting rid of the pimples, there are more hygienic and safe methods you should use — never do it with your bare hands, that’s for sure.

How pimples form

It helps the discussion if we first learn what causes blemishes.  It all starts in the hair follicles which contain the oil-secreting sebaceous glands. These glands are found the most on the face and scalp compared to other parts of the body, and there’s no coincidence why these areas are the most prone to pimples.

The glands’ function is to secrete oil to lubricate the hair, but when hair or skin dies the pores the oil oozes through are blocked. This creates an excess of oil in the pores which are forced by physics to expand under the skin in the shape of a water balloon. By this time, the skin looks red, puffy and infected.

When you squeeze a pimple, there’s a high risk of forcing debris of bacteria and dead skin deeper straight to the follicle. The follicle wall might rupture then and spill infected material into the dermis, which is the innermost layer of the skin. Even if you pull out a lot of that nasty goo, chances are infected material tunneled the dermis from below because of the pressure you exerted.

Popping pimples can lead to:

  • Scarring. This is quite rare and happens when you pick a pimple so deeply so that you would get a hole. It can still happen though when some people get carried overboard.
  • Scabs. A big white head pimple can ruin your morning, especially if a meeting is due but living with it may be better than the alternative: a nasty, crusty scab. This happens because the skin thickens or darkens to protect itself from injury. Unfortunately, brown spots or hyperpigmentation is harder to clear up than a pimple itself and can take months to get rid of.
  • Infection. In some cases, medical attention may be required.
  • Pain. Especially the big ones — those hurt like hell.
  • New pimples. The good from a squeezed pimple can block other pores and lead to the formation of new pimples.

A hands-off approach when it comes to your skin may be for the best, even though it might seem socially awkward not to.

How to pop a pimple the right way

Whiteheads will come away by themselves in about a week, which might seem like an eternity to a teenager. If you really insist, there are some safe methods you can use to get rid of some pimples.

Use two cotton swabs instead of your fingers, or better yet a sterilized needle. Wait for the pimple to come to a head, then squeeze with the cotton swabs. Stop squeezing when you see blood and then spot-treat the pimple by applying a tiny bit of hydrocortisone. Make sure you apply it only on the zit.

Before attempting anything, it’s important you thoroughly wash your hands and rub alcohol on your fingers to sterilize them. Always apply pressure gently so you don’t push debris down the follicle.

If you have a nuclear meltdown on your face, then you could visit a dermatologist. The doctor will use special tools like a cortisone shot or even lasers to extract your whiteheads and blackheads or drain a cyst.

If it’s a blind pimple — big red bumps under the skin– then there’s nothing you can do. Attempting to pop it will only make it worse as you can get the skin injured. Wait for it.

fabulous hair

How fast hair grows, and other hairy science

On average, your scalp hair grows 0.35 to 0.45 millimeters a day — that’s half an inch per month. Depending on your ancestry (genetics), diet and hormonal state (pregnant women grow hair a bit faster; it’s also thicker and shinier), your hair will grow at a higher or lower rate.

fabulous hair

Why hair grows

The human body contains roughly 5,000,000 hair follicles, and the function of each hair follicle is to produce a hair shaft. Our early ancestors used to have most of their bodies covered in hair, like our other primate cousins. This served to conserve heat, protect from the sun, provide camouflage and more. Today, however, humans stand out from the 5,000 mammal species because they’re virtually naked, but why is that?

Scientists believe that our lineage has become less and less hairy in the past six million years since we shared a common ancestor with our closest relative, the chimpanzee. Our ape ancestors spent most of their time in cool forests, but a furry, upright hominid walking around in the sun would have overheated. One of the main theories concerning our lack of fur suggests that temperature control played a key role. Bare skin allows body heat to be lost through sweating, which would have been important when early humans started to walk on two legs and began to develop larger brains than their ape-like ancestors. Nina Jablonski, a professor of anthropology at Pennsylvania State University, says there must have been a strong evolutionary pressure to control temperature to preserve the functions of a big brain. “We can now make a very good case that this was the primary reason for our loss of hair well over 1 million years ago,” she said.

“Probably the most tenable hypothesis is that we lost most of our body hair as an adaptation to being better at losing heat from our body, in other words for thermal regulation,” Professor Jablonski said.

“We became very good sweaters as a result. We lost most of our hair and increased the number of eccrine sweat glands on our body and became prodigiously good sweaters,” she told the American Association for the Advancement of Science meeting in Boston.

Besides sweating, losing our furry coat may have also been driven by having fewer parasites infesting our bodies like ticks, lice, biting flies and other “ectoparasites.” These creatures can carry viral, bacterial and protozoan-based diseases such as malaria, sleeping sickness and the like, resulting in serious chronic medical conditions and even death. By virtue of being able to build fires and clothing, humans were able to reduce the number of parasites they were carrying without suffering from the cold at night or in colder climates.

Despite exposing us to head lice, humans probably retained head hair for protection from the sun and to provide warmth when the air is cold, while pubes may have been retained for they role in enhancing pheromones or the airborne odors of sexual attraction. The hair on the armpits and groin act like dry lubricants, allowing our arms and legs to move without chafing. Eyelashes, on the other hand, act as the first line of defense against bugs, dust, and other irritating objects. Everything else seems to be superfluous and was discarded.  It’s important to note, however, that we haven’t exactly shed our fur. Humans have the same density of hair follicles on our skin as a similarly sized ape. Just look at your hands or feet: they’re covered in hair, but the hair is so thin you can barely make them out.

How hair grows


Image: Apollo Now

Hair, on the scalp and elsewhere, grows from tiny pockets in the skin called follicles. Hair starts growing from the bottom of the follicles called the root, which is made up of cell proteins. These proteins are fed by blood vessels that dot the scalp. As more cells are generated, hair starts to grow in length through the skin, passing an oil gland along the way. Emerging from the pit of each of these follicles is the hair shaft itself. By the time it’s long enough to poke out through the skin, the hair is already dead, which is why you can’t feel anything when you get your hair cut.

The hair shaft is made out of a hard protein called keratin. There are three main layers to the hair shaft. The inner layer is called the medulla, the second is the cortex and the outer layer is the cuticle. It is both the cortex and the medulla that holds the hair’s pigment, giving it its color.

Some quick facts about hair:

  • You’re born with all the hair follicles you’ll ever have – about 5 million of them. Around 100,000 of these are on your scalp.
  • The hair on your head grows about 6 inches a year. The only thing in the human body that grows faster is bone marrow.
  • Males grow hair faster than females due to testosterone.
  • You lose between 50 to 100 strands of hair each day. That’s because follicles grow hair for years at a time but then take a break. Because follicle growth isn’t synced evenly, some take a break (causing the hair to fall out), while the vast majority continue business as usual.
  • Some follicles stop growing as you age, which is why old people have thinning hair or grow bald.
  • Everybody’s hair is different. Depending on its texture, your hair may be straight, wavy, curly, or kinky; thick or thin; fine or coarse. These are determined by genetics, which influences follicle shape. For instance, oval-shaped follicles make hair grow curly while round follicles groom straight hair.
  • Like skin, hair comes in various colors as determined by the same pigment called melanin. The more melanin in your hair, the darker it will be. As you grow older, your hair has less and less melanin, which is why it fades color and may appear gray.

Hair growth cycle


Image: Belgravia Center

Follicles have three phases: anagen growth, catagen no growth, preparing for rest, and telogen rest, hair falls out. At its own pace, each strand of hair on your scalp transitions through these three phases:

  • Anagen. During this phase, cells inside the root start dividing like crazy. A new hair is formed that pushes out old hair that stopped growing or that is no longer in the anagen phase. During this phase, the hair grows about 1 cm every 28 days. Scalp hair stays in this active form of growth for two to six years, but the hair on the arms, legs, eyelashes, and eyebrows have a very short active growth phase of about 30 to 45 days. This is why they are so much shorter than scalp hair. Furthermore, different people, thanks mostly to their genetics, have differing lengths of the anagen period for a given body part compared to other people.  For the hair on your head, the average length of the anagen phase is about 2-7 years.
  • Catagen. About 3% of all the hair on your body this very instant is in this phase. It lasts two to three weeks and during this time, growth stops.  During this phase, the hair follicle will actually shrink to 1/6 of its original length.
  • Telogen. About 6 to 8 percent of all your hair is in this phase — the resting phase. Pulling out a hair in this phase will reveal a solid, hard, dry, white material at the root. On a day-to-day basis, one can expect to shed between 100 to 150 pieces of hair. This is a normal result of the hair growth cycle. When you shed hair, it’s actually a sign of a healthy scalp. It’s when the hair loss is excessive that you should feel worried and contact a doctor.

Why hair only grows to a certain length


Each hair grows out of a follicle and as the hair gets longer and heavier, the follicle eventually can’t hold on much longer and it sheds the hair. But that’s okay: it then starts growing another one. How long you can grow your hair depends on your genetics, and in general, Asians can grow their hair longer than Europeans. This may be surprising for many, but as in all mammals, each of us has a certain hair length beyond which the hair simply won’t grow. Hair length is longest in people with round follicles because round follicles seem to grip the hair better. So, people with straight hair have the potential to grow it longer. Shorter hair is associated with flat follicles. A study published in 2007 also explains why Japanese and Chinese people have thick hair: their follicles are 30% larger than that of Africans and 50% larger than that of Europeans.

In most cultures, women keep their hair longer than men. Cultural rules aside, hair length is actually sexual dimorphic. Generally, women are able to grow their hair longer than males. European males can reach a maximum length of wavy hair to about shoulder length, while the maximum for straight hair is about mid-back length. For European females, wavy hair can usually reach the waist, and straight hair can reach the buttocks or longer.

The world's longest documented hair belongs to Xie Qiuping (China) at 5.627 m (18 ft 5.54 in) when measured on 8 May 2004.

The world’s longest documented hair belongs to Xie Qiuping (China) at 5.627 m (18 ft 5.54 in) measured on 8 May 2004.

How to grow your hair faster and longer

While genetics caps your hair length, it is possible to accelerate its growth rate.

1. First of all, your hair growth reflects your general body health. Eat a diet rich in marine proteins, vitamin C (red peppers), zinc (oysters), biotin (eggs), niacin (tuna) and iron (oysters) to nourish strands.
2. If changing your diet isn’t possible, you can try supplements with marine extracts, vitamins, and minerals that nourish your follicles.
3. Besides general health, the next thing you should mind is your scalp health. Use a shampoo that gently exfoliates oil and debris from the scalp as well as a conditioner to moisturize scalp and hair.
4. Trimming is a proven method to grow your hair longer. Although in itself trimming doesn’t promote growth, it does help prevent breakage and, therefore, increases hair length.

Things that actually hurt your hair:

1. Silicone shampoos dry out the hair and degrade it. Blow dryers and flat iron produce similar effects, breaking the hair shafts. Use these products as rarely as possible.
2. UV light bleaches and breaks down hair. When you’re out at the beach, wear a hat to protect your scalp.
3. Salt and chlorine water both soften and dry the hair.
4. Bleaching, dyeing, hair extensions and perms also damage hair.


How your body heals itself after a wound

The body is pretty amazing. Cuts and other wounds can happen for lots of different reasons; you could trip and fall or have a more serious accident. Luckily, the body is well equipped to seal up a wound and heal it quite quickly. When our layer of skin is broken, a few very important steps occur that help to keep out harmful bacteria and build a new layer of skin.

The first steps of healing

The first thing that happens when the skin is penetrated is that you bleed. Normally, the blood cells stick together and form clots quite quickly, within the range of seconds to minutes. A type of blood cell called a platelet and a protein called fibrin help to form the clots and keep them in place. The clots form an initial layer that keeps more blood from being lost. Once they dry, these clots turn into scabs. The body needs to seal up the wound as soon as possible, because the skin exists to keep germs out and without a protective layer, bacteria can come in and cause infections.

The stages of wound healing. Image credits: OpenStax College.

Next, any bacteria at the site are taken care of and the healing process begins. At this point, the wound is initially inflamed and the surrounding skin can be warm to the touch and red. The blood vessels open up a bit again and deliver much-needed oxygen and nutrients to the wound. The white blood cell called a macrophage steps in to tackle any unwanted bacteria and produce growth factors that help to repair the wound. At this point, a clear fluid can often be seen on or around the wound that help to clean the area. After dead cells and bacteria are taken care of, the macrophages leave. This step is important because inflammation that lasts too long is a sign that the healing process isn’t going so smoothly. This stage takes two to five days on average.

Producing scar tissue

After the initial swelling, the tissue starts to get rebuilt underneath the scab. More blood cells come to the scene to build new tissue. Collagen — tough white fiber– is built first, as a result of chemical signals, and it serves as a framework on which other tissues can be built. Broken blood vessels also need to be repaired. Granulation tissue fills the wound and skin tissue forms on top of it. It starts forming at the edges and works its way to the center. When the skin below it is ready, the scab sloughs off on its own. A deep cut can take three to six weeks to heal.

When the scab comes off, new scar tissue underneath is revealed. Scar tissue is different from skin tissue in that it doesn’t contain sweat glands or hair follicles. It can still be a bit tender and reddish at first, but it strengthens over time. It takes about three months for the scar tissue to become as strong as normal skin and a few years to heal completely. Superficial wounds usually heal without a scar, while permanent scars are more likely with deeper wounds, though they do fade over time.

Helping and disrupting the healing

It is important to keep wounds clean and covered to help with the healing process. Minor wounds should be washed with water and covered with sterile gauze or a bandage. Major wounds should be treated with a doctor’s advice.

It’s is important to make sure that a wound is well covered. Image credits: Public Domain Pictures.

Usually the healing process goes smoothly, especially if you take care of it well. However, there are cases where it doesn’t go as well as wished. If a wound doesn’t have adequate blood supply then it doesn’t receive the ingredients that it needs to heal, namely oxygen and nutrients. It can take twice as long or even longer to heal. It can take longer for the wounds of elderly people, and people with diabetes, high blood pressure, obesity, and other vascular diseases to heal. Stress, smoking, certain medicines, and heavy alcohol drinking can also interfere with wound healing. There are some warning signs that a wound isn’t healing properly that include pus and a fever, which could mean that it is infected. In this case, it is important to see a doctor.

The wound healing process allows us to be active and survive life’s little accidents by regenerating our largest organ.

Although they appear identical, baking powder and baking soda are slightly different. Credit: Eat By Date.

What’s the difference between baking soda and baking powder: science to the rescue

Although they appear identical, baking powder and baking soda are slightly different. Credit: Eat By Date.

Although they appear identical, baking powder and baking soda are slightly different. Credit: Eat By Date.

Baking soda and baking powder look and sound the same. To make matters even more confusing, they’re often used in the same recipes. However, knowing what sets these two popular ingredients apart could mean the difference between the perfect baked goods or a smooshed fiasco.

What’s baking soda

Baking soda is, essentially, ground up rock — which means it can last indefinitely (if properly stored). More specifically, baking soda is the colloquial term for sodium bicarbonate, a base that reacts quite energetically when encountering an acid such as buttermilk, yogurt, or vinegar (our brains register acid substances as ‘sour’). Mixing baking soda with an acid will produce carbon dioxide — because in this kitchen this reaction usually takes place in a liquid, it also produces bubbles. This property is what makes the substance so useful for bakers. Mix some baking soda into the proper dough, and it will generate carbon dioxide. As the mixture stiffens and the gas escapes, enlarged air pockets are left behind, making the end product fluffy and soft.

Due to this behavior, you’ll often see baking soda mentioned in recipes which include many acidic ingredients like molasses, maple syrup, lemon juice, and pumpkin. In such cases, baking soda works as a leavener, helping the dough rise.

When added to a mixture, baking soda will raise the pH, slowing down protein coagulation — the process that leads to the stiffening of a food as it cooks or bakes. This helps the bake good spread before it sets, helping the food bake more evenly.

Baking soda is also an excellent cleaning agent.  It’s a super-effective (but gentle) abrasive and is a great natural deodorizer, so it’s helpful in all sorts of cleaning emergencies, from unclogging drains to deodorizing the carpet.

Someone who sure loves baking soda…

What’s baking powder

Sometimes, you don’t want the rising to take place all at once, which is where baking powder comes in. Baking powder is a mix made from baking soda (sodium bicarbonate) and two acids for it to interact with and produce CO2 gas at different stages of the baking process. This is “double acting” baking powder; single-acting baking powder contains only one acid, which reacts fully when you combine it with another liquid.

One of the acids in baking powder is monocalcium phosphate, which unlike most acids — like, say, vinegar — doesn’t immediately react with the sodium bicarbonate while it’s dry. It’s only when the sodium bicarbonate is wet, such as when it’s stirred into a wet dough, that the two ingredients begin to react, releasing CO2 bubbles and causing chemical leavening.

Baking powder usually contains a second acid, typically sodium acid pyrophosphate or sodium aluminum sulfate (soda alum), which extends the chemical leavening process. Neither of the two acids will react with the base until the sodium bicarbonate is both wet and hot — in other words, not until you put the dough in the oven. This way, the batter can rise for a longer period of time, leading to a fluffier cake or muffin. Without the two special kinds of acids, baking powder’s heavy lifting powers in the oven would be gone — and we’d all end up with some pathetic, saggy bake goods.

Since baking powder is only one-fourth baking soda, it is also just one-fourth as powerful as baking soda. The upside, when using baking powder, it that it isn’t necessary to add an acid. Instead, baking powder starts to work when any liquid is added.

Both baking powder and baking soda need to be stored in a cool and dry place. The extra moisture in the air can start the reaction between the acids and base. And like baking soda, it is important to bake the mixture right away, or else the mixture will collapse.

So, there you have it: baking soda is made out of a single ingredient, while baking powder is a mix of baking soda and at least one acid. But which of the two should you use in the kitchen? That’s simple: when baking a recipe which already contains an acid as one of the ingredients, use baking soda. If there are no acids in your recipe, use baking powder instead.

Happy baking!

What are some pollinating animals — other than bees

When you think of pollinators, you probably think of honeybees. It is true—they are the most economically important pollinators and are responsible for most of the fruits and vegetables that we eat. But they are not the only ones. In terms of pollination services, honeybees provide 39%, while non-bee animals provide 38% and other bees provide 23%. So, pollinators other than bees pollinate as much as honeybees — who knew? In the USA alone non-bee pollinators provided pollination services that contributed to $10 billion of crops in 2010, while honeybees contributed to over $19 billion.

Pollination involves moving pollen from the male part of a flower, the stamen, to the female part, the stigma, and subsequent fertilization. When fertilized, the plant often produces a fruit and seeds. Pollinators usually get covered with pollen when gathering pollen or nectar from a flower. When they move to the next flower, the pollen can reach the stigma and cause pollination. There is an incredibly large range of non-bee pollinators that includes flies, butterflies and moths, beetles, ants, birds, bats, and wasps.

Here are some of the other pollinators that shouldn’t be overlooked:


Hoverflies (Syrphidae family) are often thought to be the most important pollinators after bees. Most pollinate a variety of flowers without being too picky, but some flowers specifically try to attract certain hover flies by mimicking aphid pheromones or their favorite colors. They can effectively pollinate sweet peppers, strawberries, and other economically important plants.

Don’t be fooled, this isn’t a bee or a wasp, but a hoverfly! Image credits: Pixabay.

Another group of important pollinating flies are bee flies (Bombylius species). If you look at them quickly you might think that they are bees, but they are only imitators. Although they look like bees, their larvae actually feed on bee larvae. Bee flies have very long proboscises to pollinate flowers that have narrow, deep tubes. Other flies that pollinate are some male Bactrocera fruit flies and even adult mosquitos. They like pale and dull flowers with lots of pollen.

This little fuzzball is called a Bombylius major, a bee fly. Image credits: Rror.

Carrion flies pollinate flowers that have a fetid odour, similar to rotting meat, dung, humus, or blood. These flowers are often also purple or red to seem even more like meat. Some of the carrion flies get tricked into laying their eggs on these flowers; their larvae starve due to lack of carrion.


Different from bees, many wasps catch prey to feed their larvae instead of pollen, which is why they have stingers. Wasps need a lot of energy like bees. They are not as important pollinators as bees, because they are not fuzzy and therefore pollen doesn’t stick to them as much. Wasps from Masarinae, a subfamily of Vespidae, are called pollen wasps because they gather pollen to feed their larvae.

You can see the fig wasps in the cross-section of a fig. Image credits: Prashanthns.

Figs are fruit that depend on tiny fig wasps to pollinate them. Fig flowers lie inside of immature fruit so the wasps need to be small to fit into a tiny hole to lay their eggs and pollinate. Fig wasps pollinate almost 1,000 different species of figs.

Butterflies & moths

Butterflies are not built for pollination, with their slender legs and elevated bodies, but they do transport some pollen as they flit from flower to flower in search of nectar. Butterflies like flowers that contain a lot of nectar. They have good vision and are attracted to flowers that are brightly colored — such as red, orange, and yellow. They like flowers in clusters, with a landing platform.

Yucca moth pollinating a yucca plant. Image credits: Joshua Tree National Park.

Moths also pollinate plants, though ones that flower at night. Some moths are specially adapted to certain plants.  Some orchids are dependent on moths such as the hawk moth or Morgan’s sphinx. Yucca plants depend on Yucca moths to pollinate them. The flowers that moths pollinate are similar to those for butterflies except that they are usually a dull color.


Beetles were among the first pollinators to visit flowers 200 million years ago, and they are still important! As you can imagine, some, more ancient, plant species are pollinated by them, such as magnolias and spicebush. They often eat petals and other parts of flowers and are known for sometimes defecating in the flowers.

Beetle pollinating flowers. Image credits: Elena Motivans.

The beetles that eat pollen, nectar, or flowers are the most important pollinators. They go for dull, fruity flowers that are open during the day—they can be large solitary flowers or clusters of small flowers.


The most well-known bird pollinators are, of course, hummingbirds. However, there are also other important bird pollinators, such as honeycreepers in Hawaii and honeyeaters in Australia. Brush-tongued parrots in New Guinea and sunbirds in the tropical old world also pollinate, especially deep flowers. In total, 2,000 bird species feed on nectar and therefore transport pollen to some degree.

A sunbird pollinating a flower in Kenya. Image credits: Steve Garvie.

The most attractive flowers for birds have petals that are curved out of the way, strong supports for perching, bright colors, and lots of nectar that is deep down. When the birds thrust their heads into the flowers to get the nectar, pollen sticks to their heads. Hummingbirds eat a lot of nectar, several times their weight each day, to have enough energy to beat their wings 70 times a second.


These flying mammals are important pollinators of some flowers in the tropics and deserts, more specifically in Africa, Southeast Asia, and the Pacific Islands. Two examples of bats that feed on nectar are the lesser long-nosed bat (Leptonycteris yerbabuenae) and the Mexican long-tongued bat (Choeronycteris mexicana).

A bat drinking nectar from a cactus flower. Image credits: U.S. Fish and Wildlife Service Headquarters.

Flowers that bats like are open at night, large, pale, fragrant, and contain lots of dilute nectar. Bats not only feed on the nectar, but also on insects in the flower. Though you might think that bats aren’t important pollinators, they are responsible for pollinating plants like mangoes, bananas, guavas, and agave.


There are also some surprising pollinators, like mammals and lizards. Monkeys, lemurs, possums, rodents, and lizards are known to pollinate some plants. The largest pollinator in the world is the black and white ruffed lemur (Varecia variegata), which pollinates the traveler’s palm. The flowers are very tough and the lemurs pull them open and stick their snouts and tongues inside. Pollen sticks to their fur, which is then transported to the next flower. Honey possums (Tarsipes rostratus) have a tail that lets them hang from branches to look for flowers, and a very long tongue to drink nectar. They pollinate banksia and eucalyptus flowers. Some other mammals, like bush babies and sugar gliders also pollinate.

The world’s largest pollinator. Image credits: Charlesjsharp.

Even lizards can pollinate! An example is the Noronha skink (Trachylepis atlantica) from Brazil. It drinks the nectar from the leguminous mulungu tree’s flowers. The skinks climb inside the flower to drink and, in the process, the pollen sticks to their scales and gets deposited when they visit another flower.

It’s true—pollinators are more diverse than just the honeybees. We depend on all of them for the beautiful flowers and tasty fruits and vegetables in the world.

Witness the birth of an octopus at the Virginia Aquarium– and learn how it happens

A video from the Virginia Aquarium has gotten over 1.5 million views. In the video, a baby octopus hatches from a teardrop-shaped egg, turns brown, and swims away. It looks a bit like you would imagine an alien being born, except much cuter. It is a fascinating display and raises the questions of how octopuses are born and why they turn brown.

Footage of the baby octopus being born, in case you haven’t seen it yet. Video credits: YouTube/KRIS 6 News.

Octopuses usually don’t live so long — six months to five years on average — so they grow and reproduce quickly. When it is time to mate, male octopuses look for females. The males have an arm that is modified to deposit sperm. Some species of octopuses insert the sperm-arm into the female’s oviduct and others take off the arm and give it to the female to store in her mantle. The female then keeps the arm and spreads it over her eggs when she gives birth to fertilize them.

The mother octopus arrived at the Virginia aquarium half a year ago and laid 100-200 eggs two months ago. It was surprising that they were fertilized, because she is alone in the aquarium. She must have mated with a male in the wild; her species of octopus (Caribbean reef octopus) can store sperm for up to 100 days.

Once the female has laid eggs she doesn’t eat and incubates her eggs for 2-10 months. She circulates water currents over the eggs to clean them and protects them from predators. The male dies soon after mating and the female dies soon after her eggs hatch.

An octopus or squid larva. Image credits: NOAA Photo Library.

Some octopuses, usually the ones that are born near the ocean’s surface, start life very tiny. The ones at the Virginia aquarium are no bigger than the size of a pinky fingernail, despite looking much larger in the video. When they are the size of a golf ball, the aquarium will display them to the public. A baby octopus increases its weight by 5% every day so they grow very quickly. Octopuses are very efficient at turning food into body mass; at the end of its lifetime, an octopus weighs as much as a third of the food that it has consumed over its lifetime.

It was the aquarium’s first attempt to hatch octopuses, and 15-20 other babies have the born over the past few days. It isn’t unusual for newly hatched octopuses to change colours because the stress of hatching can cause its chromatophores, pigment-containing cells, to fire. Another reason could be that the octopus was trying to camouflage against the dark tabletop beneath it. Unfortunately, the outlook for baby octopuses isn’t so rosy; their survival rate is extremely low. For example, only 1% of giant Pacific octopuses grow to be 10 millimeters large.


Animal files: the paradoxical axolotl

The axolotl. Image credits: Bouboulski.

The axolotl (Ambystoma mexicanum), otherwise known as the Mexican Walking Fish, is perhaps the most recognizable salamander in the world. It is commonly kept as a pet and used for scientific research, however, natural populations are severely reduced, with only a few hundred estimated to be living in the wild now.

Axolotls look different from most other salamanders because they are neotenic. This means that even when they become adults, they keep the traits usually only seen in juveniles; they keep their gills and live in the water their whole lives. In contrast, most other salamanders lose their gills and live on land. They are native to Lake Xochimilco and Lake Chalco, however these lakes do not exist anymore. Mexico City was built on top of them and they were mostly drained. All that remains of the Xochimilco are canals, which are now the only suitable habitat for axolotls.

Most axolotls in the wild are black or brown, but pets are often albino. The albinos are very rare in the wild but liked by breeders and often interbred. Axolotls are very closely related to tiger salamanders (Ambystoma tigrinum) and many axolotls in captivity have been interbred with tiger salamanders. So they are so closely related that they can produce viable offspring together. However, unlike axolotls, tiger salamanders mature and then live on land.

Axolotls are very interesting for scientific research. First off, they can regenerate limbs and organs, including brain tissue. Perhaps this trait is due to them being continuously in an embryonic form. When axolotls become injured, nearby cells are turned in stem cells and other cells from all over the body are called over to the site of the injury. All the tissues develop in almost the same way as when the salamander was still developing in the egg. In contrast, human wounds just get covered with skin tissue. Scientists are trying to learn from the axolotl how to regenerate damaged human tissue.

Leucistic axolotl. Image credits: th1098.

Axolotls are easy to study because they survive easily and have very large cells. The cells have different pigmentation so they are easier to keep track of than human cells, which are more difficult to distinguish from each other. They are used as models for development and cancer. One challenging aspect in using it for research is its large genome size, which is about ten times as large as a human genome. The salamanders have already contributed to many important scientific discoveries, such as how cells and organs function and develop in vertebrates, the causes of spina bifida in humans, and the discovery of thyroid hormones. That last discovery is particularly interesting. Researchers in the 1920s fed axolotls thyroid tissue from livestock animals. The hormones cause the axolotls to “grow up” and lose their gills and larval skin. Axolotls occasionally mature on their own as well.

One big problem is that all of the axolotls in captivity have been interbred for a long time and are very inbred. Most have been bred from 34 salamanders taken in 1863. This makes them very vulnerable to illness and one disease could wipe them all out. Therefore, it is critical to protect the wild population to maintain the genetic diversity preventing the species from becoming inbred. Unfortunately, the situation is critical. The two main problems are non-native fish, that are eating them, and water pollution. Immediate action is needed to protect them from extinction.

Researchers are trying to work with fishermen to take out the non-native fish and tackle the water pollution problem, but they are having trouble finding enough money to carry out their research. It is a challenging mission, but hopefully one that will be successful in the end.


A few unbelievable bacteria facts

Bacteria are the most abundant living organisms on earth. There are approximately five million trillion trillion (no, the second trillion was not a typo) bacteria on earth. They inhabit pretty much everywhere, from deep-sea thermal vents to an icy Antarctic lake to inside of our own bodies. Because there are so many different types, these single-cellular organisms are far from boring. Here are just a few interesting facts about bacteria.

We are (at least) half made up of bacteria cells

It is often cited that are ten times more bacterial cells than human cells in a person; however, a recent study has cast doubt on this number and concludes there are only about 30% more bacterial cells. You might read somewhere that this makes us more bacteria than human. While true number-wise, these bacteria cells are actually much smaller than human cells and would only fill up a large soda bottle (2 L or 0.5 gallons) in volume. Therefore, they only make up 1-2% of our body weight. Either way, that is still a lot of bacterial cells (39 trillion bacterial cells).

Bellybuttons have unique bacterial fingerprints

Your bellybutton’s bacteria create a unique fingerprint for you. In a citizen science project, researchers swabbed 60 bellybuttons and identified the bacteria from each. They identified a grand total of 2,368 species of bacteria, with 1,458 that could be new to science. No bacteria was found on every person. Some bellybuttons were three times more diverse than others but the average number of different bacteria in a bellybutton was 67. Eight species were found on more than 70% of people and they occurred in large numbers. Most of the time, the bacterial species was only found on one person or a handful. One individual, who hadn’t washed in a few years, had two extremophile bacteria species that usually live in extreme environments, such as on ice caps and thermal vents. One person had a bacteria that had only been previously found in soil in Japan before, even though he had never been to Japan.

Your bellybutton bacteria is as unique as a fingerprint. Image credits: Pixabay.

Radioactive-proof external storage

Messages can be stored in the DNA of bacteria and then retrieved. Scientists were trying to find a new way to store information, so they tried within the living cells of bacteria. Specifically, scientists want to be able to store important information in the event of a nuclear catastrophe. They chose the bacteria Deinococcus radiodurans to store the information because it can survive high temperatures, drying out, UV light, and radiation that is 1000x higher than a human’s fatal dose. If you decide which piece of information you would want to survive a nuclear disaster, you’d choose “It’s a Small World”, right? That’s what the scientists did for this study. They coded the song to the four bases of DNA and inserted parts of the songs into the bacteria.

This bacteria can survive a lot of radioactive radiation. Image credits: Credit: TEM of D. radiodurans acquired in the laboratory of Michael Daly, Uniformed Services University, Bethesda, MD, USA.

Bacteria are responsible for B.O.

If your underarms are smelly, you can blame bacteria. We produce two types of sweat: one is eccrine sweat, which is mostly salty water, and the other is apocrine, which attracts smelly bacteria. One gene is responsible for whether you smell when you sweat: ABCC11. This gene is also responsible for whether you have wet or dry earwax. If you have wet earwax, then you also have a protein that transports the sweat out of pores in the armpit, where it attracts bacteria that cause body odour. Those with dry earwax (much more common in Asia than Europe) don’t produce the protein, so they don’t make the apocrine sweat that smells.

People who have the specific gene don’t need to use deodorant. Image credits: twitchery.

Bacteria talk!

Bacteria communicate with each other using electrical signals. In this way, single-celled bacteria can act like a multicellular organism. A colony of billions of cells can communicate and work together like a “microbial brain”. This is especially true for biofilms, which are conglomerations of bacteria; these build up on rocks in rivers. They can also build nanotubes to bridge between different cells to exchange small molecule, proteins, and plasmids.

Staphylococcus aureus biofilm, which acts a bit like a multi-cellular organism. Image credits: Public Health Image Library.

Make it rain

Bacteria can even cause rain and snow to form. Around the world, cells and cell fragments with DNA were found in the center of some snowflakes. Some of them even have special proteins to form ice. Pure water in the atmosphere won’t freeze until it is -40˚C /˚F unless there is some particle like dust in the middle to help the water particles arrange themselves into the right shape to form a crystal. These particles are called nucleators, and they allow ice to form at around 0˚C /32 ˚F. Bacteria are among the most effective ice nucleators because of the proteins that they possess, though only a few species can do it. If this happens in the winter, it snows and if it happens in the summer, it rains. Some researchers have suggested spraying bacteria into clouds to end a drought.

Bacteria are responsible for a lot of snowflakes. Image credits: Max Pixel.

Bacteria are pretty incredible!

Curious facts about red pandas

Red pandas may be cute, but they have been a headache for biologists since their discovery. We may have just finally discovered where red pandas belong in the tree of life, and they are unlike anything else alive today. These small mammals are distinguishable by their rusty redcoloured fur and bushy ringed tails. They live in Southern China, Myanmar, Nepal, and India in high mountains within bamboo forests. Unfortunately, they are currently endangered.

They have been confusing biologists for almost 200 years

Other names for the red panda include cat-bear, bear-cat, lesser panda, fox bear, Himalayan racoon, and firefox (yes, the web browser is named after it). When they were first discovered by Frédéric Cuvier in 1825, he placed them in the same family as racoons because of their head shape, teeth, and ringed tails. A 1977 Nature paper also placed red pandas in the same family as racoons. Then, because of their similarity to panda bears and DNA composition, red pandas were thought to be part of the bear family. Now, they are the only members of the Ailuridae family, which is most closely related to the group containing weasels, racoons, and skunks.

The elusive red panda. Image credits: Pixabay.

Their closest relatives are long gone

Red pandas have no living relatives.Their most recent fossil ancestor, Parailurus, had a large distribution across Eurasia tens of millions of years ago. There may have been three different species of Parailurus that are all larger and had a more robust head and jaw than the red panda. The family, Ailuridae, contains seven extinct genera of animals. Fossils of jaws and other bones from extinct red panda relatives have been found in Spain, Eastern Europe, and the US. The UK is also home to a giant pandano it’s not the cuddly black and white giant panda, but an extinct relative of the red panda. A lower jaw and fossil molar of this cougar-sized beast were found in 1888.

Almost a wah?

An English naturalist, Major General Thomas Hardwicke, presented the discovery of the red panda to the Linnean Society in London in 1821. He was likely the first Western scientist to discover the red panda, which he did so during his service in India. He gave a presentation entitled “Description of a new Genus of the Class Mammalia, from the Himalaya Chain of Hills Between Nepal and the Snowy Mountains.” He thought that it should be called a “Wah” because of the sound of its call for which the locals called it the Wha or Chitwha. Hardwicke’s paper was only published two years after Cuvier’s description in 1825, which meant that he lost the right to name the species.

Major General Thomas Hardy actually described the red panda first. Image credits: Drawn by J. Lucas; Lithograph Louis Haghe.

Red pandas are not giant pandas

Actually, red pandas were the first animal to be called “panda”. Frédéric Cuvier, a French zoologist, first described the red panda in 1825 and called it Ailurus fulgens (fire-coloured or shining cat) after its cat-like appearance and bright fur colour. The origin of “panda” is unknown but could be from the Himalayan language or the French name for the Roman goddess of peace and travellers. The giant panda was not described until 1873 and also named panda because of its similarities to the red panda.

Giant and lesser pandas share a love of bamboo and high mountains in Asia, and “thumbs”. Image credits: Pixabay.

Both the red panda and giant panda eat mostly bamboo and live in high-altitude forests in Asia. Both pandas have a sort of thumb created from a modified wrist bone that is only used for holding the bamboo when they feed. This is an example of convergent evolution, as the animals are not closely related, though the thumbs evolved in the two pandas for different reasons. In contrast, giant pandas are not picky at all and will eat every part of bamboo, while red pandas only eat leaf tips and shoots, which are more nutritious.

Vegetarian by choice

Although red pandas are most closely related to carnivores and they have a carnivore stomach, they mostly eat bamboo and other plants. On rare occasions, they’ll hunt a small mammal or bird and eat bird eggs. This trait is also similar to most species of bears, which also eat a mostly vegetarian diet, with the exception of the polar bear.

A red panda enjoying its food of choice: bamboo leaves. Image credits: Mattis2412.

Other unique facts

When presented with water and sweetened water, red pandas preferred the water with artificial sweeteners, making them the only known non-primate to be able to taste aspartame. In colder temperatures, red pandas become dormant, with a very low metabolism rate, which they only shake out of to get food. Additionally, they mark their territory with a clear liquid produced by glands between their footpads. The red pandas have a cone-like structure at the bottom of their tongues to test odours and bring items close to a gland in their mouths.

Red pandas have a sweet tooth. Image credits: Fort Greene Focus.

Even though we know how to classify red pandas, they are still unique animals that need our protection so that they don’t go the way of the rest of their taxonomic family.

These are the cities with the worst traffic (continent by continent)

Traffic is a growing problem in many parts of the world, but if you’re going to these cities — pack some extra patience.

In 2004, a company TomTom launched the first personal navigation device, and the world would never be the same. Since then, they’ve sold tens of millions of such devices around the world, and as a result, have access to a trove of data about the world’s traffic. They’ve charted the world’s cities based on how bad the traffic is, based on a congestion score which shows how much extra time you need to navigate that city. A 33% score means you need 33% more time.

We’ll only consider large cities here (over 800,000 people), though TomTom also has ratings for some smaller cities. Let’s have a look at the worst cities overall, and then we can break it down continent by continent.

Worst traffic in the world

  • 10. Beijing (China) — 46%

China’s bustling capital “only” comes in at number ten, despite being the world’s second most populous city proper. Thanks to its national highways, expressways, and high-speed rail network, things aren’t worse, but even these thick veins can’t keep up with the over 21 million people who call Beijing home.

  • 9. Tainan (Taiwan) — 46%

The congestion of this Taiwan municipality grew by a whopping 10% since last year, in part due to tourism.

  • 8. Rio de Janeiro (Brazil) — 47%

Despite remaining stable since last year, Rio’s streets are still a nightmare to drive on. Rio is surrounded by mountains, and that makes traffic management even more difficult.

  • 7. Chengdu (China) — 47%

Unsurprisingly, China’s sparkling metropoles often have massive traffic problems, largely due to the fact that they weren’t designed to fit so many people.

Despite many people cycling, China’s growing cities still have a massive traffic problem. Traffic jam in Chengdu, image in Public Domain.

  • 6. Istanbul (Turkey) — 49%

Despite a slight improvement from last year, the roads of Istanbul are still a chaotic drag to navigate. Traffic jams are a common sighting, as are drivers trying to improvise their way out of a jam and making it much worse.

  • 5. Bucharest (Romania) — 50%

Perhaps surprisingly, the Romanian capital of Bucharest is Europe’s most congested city. Improper city planning and an overall disregard of such problems have made driving in Bucharest worse and worse, after year.

Bucharest does have its traffic, but it’s certainly not on the road. Image credits: Babu / Wikipedia.

  • 4. Chongqing (China) — 52%

The most congested city in China (though not in Asia) is Chongqing, a municipality which was created only in 1997, but now has a population of over 18 million.

  • 3. Jakarta (Indonesia) — 58%

Everyone who’s ever been in Jakarta will tell you its streets are a nightmare. Jakarta’s business opportunities, as well as its potential to offer a higher standard of living, attract people from all over Indonesia, but that’s taking a toll on the streets.

  • 2. Bangkok (Thailand) — 61%

Asia’s most congested city is Bangkok. The city hosts 12.6 percent of the country’s population, dwarfing all other urban centers in Thailand, but also having the obvious downside of bad traffic.

The traffic in Bangkok — sometimes you move, and sometimes… you just don’t. Image credits: Mark Fischer / Flickr.

  • 1. Mexico City (Mexico) — 66%

According to TomTom, the world’s most congested city is by far Mexico City. From morning to evening, the city’s streets are clumped with cars that seem to be going nowhere — and often, they really are going nowhere.

Worst traffic in North America

Congestion is getting worse and worse in America. The average US commuter spends 42 hours stuck in traffic a year, according to a report by the Texas Transportation Institute.

The United States takes seven spots, Canada takes two, but Mexico tops the charts.

  • 10. Portland (US) — 29%
  • 9. Miami (US) — 30%

Rush hour in Miami is absolutely awful. Image credits: B137 / Wikipedia.

  • 8. Toronto (Canada) — 30%
  • 7. San José (US) — 32%
  • 6. Seattle (US) — 34%
  • 5. New York (US) — 35%

Few things are as recognizable as a New York traffic jam, and according to this data, there’s lots of them. Image credits: joiseyshowaa.

  • 4. Vancouver (Canada) — 39% 
  • 3. San Francisco (US) — 39%
  • 2. Los Angeles (US) — 45%
  • 1. Mexico City (Mexico) — 66%. Worst traffic in the world.

This photo by Dennis Mojado sums up the traffic in Mexico City quite nicely.

Along with the mayors of Paris, Athens, and Madrid, Mexico City has vowed to ban all diesels from the city by 2025.

Worst traffic in Europe

The United States takes seven spots, Canada takes two, but Mexico tops the charts.

  • 10. Athens (Greece) — 37%

As the economy finally starts to improve in the Greek capital, the traffic also starts to become rougher and rougher.

  • 9. Manchester (UK) — 38%

Manchester has remained more or less constant in recent years. It’s bad, but at least it’s not getting much worse.

  • 8. Brussels (Belgium) — 38%
  • 7. Paris (France) — 38%

The city of lights, indeed. Due to intense traffic, Paris is also battling pollution and smog. Image credits: Nelson Minar / Flickr.

  • 6. Rome (Italy) — 40%

Rome’s traffic issues are well known, and caused in part by the municipality’s inability to build new roads and subways due to the archaeological ruins. The loads of tourists coming every year to Italy’s capital certainly don’t help.

  • 5. Marseille (France) — 40%
  • 4. London (UK) — 40%
  • 3. Saint Petersburg (Russia) — 41%

Russia seems to have a serious traffic problem. As soon as a city starts to grow, so too does the congestion. St. Petersburg and Moscow, the country’s biggest cities, are two of Europe’s three most congested cities.

  • 2. Moscow (Russia) — 44%
  • 1. Bucharest (Romania) — 50%

Worst traffic in Asia

Six Chinese cities are present in the top 10, though the world’s most populous country takes neither of the top two. It’s interesting that Asian cities tend to clump in a congestion rate of their own — all of the ten most congested Asian cities fit in the world’s top 15.

  • 10. Shenzen (China) — 44%
  • 9. Guangzhou (China) — 44%
  • 8. Changsha (China) — 45%
  • 7. Beijing (China) — 46% 
  • 6. Tainan (Taiwan) — 46%
  • 5. Chengdu (China) — 47%
  • 4. Istanbul (Turkey) — 49%

It’s noteworthy that Istanbul is the only city in all these top 10 which reports a slight improvement, though it’s not clear why this is happening.

  • 3. Chongqing (China) — 50%
  • 2. Jakarta (Indonesia) — 58%
  • 1. Bangkok (Thailand) — 61% 

South America, Africa, and Oceania don’t have data for a relevant top 10, but you can check the existing data here.

Small cities

When it comes to smaller cities (<800,000) people, Europe definitely takes the crown. You have to look until the 19th place to find a congested city that isn’t European. While small cities are definitely not as crowded as bigger ones, they too experience growing congestion, which can become a major problem in future years — and already is one in some places, especially in the UK.

Image credits: TomTom.

Animal files: Kiwi birds— unique birds

Kiwi birds are unique in a lot of interesting ways. For starters, they are only found in New Zealand and cannot fly. But that is just the beginning, they have many traits that are not found in any other bird. There are five different species of kiwi and, unfortunately, most of them are endangered to some degree.

Not a flying bird

Kiwi are only found in New Zealand and are part of the group of ratites, which includes ostriches and emus, and are actually the smallest members of the group. For comparison, they are about the same size as a chicken. Though it was expected that the kiwi would be more closely related the moa (extinct), which also lived in New Zealand, they actually are much more closely related to the elephant birds of Madagascar (also extinct). It is hypothesized that the kiwi’s ancestor was able to fly and reached New Zealand separately from moas. Once on the island, it lost its ability to fly and eventually became the kiwi bird known today. Actually, the Latin genus name of kiwi birds, Apteryx, is based on their inability to fly. The “a-” means “without” and “pterux” means “wing”. They do have very tiny, vestigial wings, but you can barely see them and they aren’t any help with levitation.

A kiwi bird. Image credits: Maungatautari Ecological Island Trust.

Some special features

Kiwi have feathers that look like hair and very strong, muscular legs. They rule the ground instead of the air. They can smell very well and are the only bird that have nostrils at the end of their beaks, which are quite long. They use their nostrils to sniff out invertebrates and seeds to eat. They can use just smell to detect food.

Kiwi birds are quite shy and usually only come out at night. Kiwi can live a long time, between 25 and 50 years. Once a male and female bond they spend their whole lives as a monogamous couple. During the mating season, they call to each other at night, and meet each other about every three days in the nesting burrow. Kiwi live in forests, scrublands, and grasslands. They sleep in burrows, hollow logs, or in the middle of dense vegetation. They are very territorial and defend their territory against other kiwi. Another weird fact is that, according to the San Diego Zoo, kiwi have the lowest body temperature of any bird, 38 °C (100 Fahrenheit).

The size of an egg inside of a kiwi. Image credits: Matt Chan.

The females carry huge eggs for their body size. A female can carry an egg up to one-quarter of their body weight. As mentioned before, the kiwi is about the same size as a chicken but its egg is actually six times as large as a chicken’s egg. The reason for this is that the kiwi bird doesn’t have to fly so there aren’t any constraints on its weight. It doesn’t need to be aerodynamic. Kiwi also has marrow in their bones, like humans, which also makes them heavier.  The female has to eat three times as much as usual to help the egg develop. Right before the egg is laid she can’t eat anything because the egg presses against her stomach, leaving no room for food. Tthe chicks hatch pretty much developed; they have feathers already and fend for themselves right from the get-go. However, they take between three and five years to grow to their full size.

The different species of kiwi

There are five different species of kiwi that live around the islands of New Zealand.

  • The great spotted kiwi, Apteryx haastii, is the largest species. In most other species, only the male incubates the egg, but great spotted kiwi mothers and fathers both incubate their eggs.
  • The little spotted kiwi, Apteryx owenii, is the smallest species. It is now extinct on mainland New Zealand because pigs, stoats, and cats have killed them. Now they just live on a few islands; about 1400 are left on Kapiti Island. They have been introduced to other predator-free islands where they are establishing themselves.
  • The Okarito kiwi, Apteryx rowi, was named a separate species in 1994 and is slightly grey coloured. It lives on a small patch of land on the west side of New Zealand’s south coast. Most kiwi species lay one egg, but these lay up to three a season, each in a different nest and both parents incubate the eggs. They are the rarest kiwi species, with just 450 left in the wild
  • The southern brown kiwi, Apteryx australis, lives on the South Island. There are three different subspecies that are recognized. They like living in the mountains and are also extremely rare.
  • The North Island brown kiwi, Apteryx mantelli, is the most common kiwi. It has survived because it can adapt to a wide variety of habitats. Females usually lay two eggs.

Apteryx mantelli, the North Island brown kiwi. Image credits: The.Rohit.

Threats to kiwi

All kiwi species are endangered. On average, twenty-seven (out of a total of 70,000) die each week. They have been affected most by deforestation and invasive mammals. Before humans came to New Zealand, the only mammals on the island were bats and seals. Therefore, birds and insects filled most of the ecological niches. The kiwi never had to worry before about predators before, but now since it cannot fly, and lays its eggs on the ground, it is pretty defenseless against invasive mammals such as rats and stoats. Stoats kill a lot of the fledglings, while dogs kill a lot of adult birds, usually by accident, because they are quite delicate.

Invasive stoats kill a lot of young kiwi birds. Image credits: Steve Hillebrand, USFWS.

In New Zealand now, there are a number of programs to try to help kiwi populations. First, is the ambitious plan to eradicate all invasive vertebrate predators from New Zealand by 2050. With no more invasive pests, the kiwi populations could again flourish, as they did before the predators were introduced. Another initiative is Operation Nest Egg, in which kiwi eggs and hatchlings are removed from their nests and reared in captivity and released when they are large enough to defend themselves against predators. This has been successful because normally, only 5-15% of kiwi chicks survive past being 100 days old. Kiwi raised in captivity are much more likely to survive to adulthood. When they weigh more than a kilogram they can protect themselves from stoats and other predators.




The reason why ice floats

Ice floats— that’s why the ocean has polar ice and icebergs, and why the ice in your drink floats. If you think about it, it might seem a bit strange because ice is a solid and intuitively, it should be heavier than a liquid and sink. Though this is true for most substances, water is an exception. Its hydrogen bonds and its solid state actually make it lighter than it is as a liquid.

Ice is less dense

Water is an amazing substance that basically fuels life on earth— every living organism needs it. It also has some interesting properties that enable life to be the way that it is. One of the most important properties is that water is the densest at 4 °C (40°F). Hot water and ice are both less dense than cool water. Less dense substances float on top of more dense substances. For example, when you make salad dressing oil floats on top of vinegar because it is less dense. The same is true for everything. If you have a blow-up beach ball in a pool, it floats, if you have a rock, it sinks.

Although it seems heavy, an iceberg is less dense than water. Image credits: NOAA’s National Ocean Service.

The reason why ice is less dense than water has to do with hydrogen bonds. As you know, water is made up of one oxygen and two hydrogen atoms. They are attached by covalent bonds that are very strong. However, another type of bond also forms between different water molecules called a hydrogen bond, which is weaker. These bonds form because the positively-charged hydrogen atoms are attracted the negatively-charged oxygen atoms of nearby water molecules. When water is warm, the molecules are very active, move around a lot, and form and break bonds with other water molecules quickly. They have the energy to push closer to each other and move quickly.

As water gets below 4 °C, the kinetic energy decreases so the molecules don’t move around so much anymore. They don’t have the energy to move and break and form bonds so easily. Instead, they form more hydrogen bonds with other water molecules to form hexagonal lattice structures. They form these structures to keep the negatively charged oxygen molecules apart. In the middle of the hexagons, there is a lot of empty space.

The structure of water molecules as they form ice, notice all the empty space. Image credits: NIMSoffice.

Ice is actually about 9% less dense than liquid water. Therefore, ice takes up more space than water. Practically, this makes sense, because ice expands. It’s why you shouldn’t freeze a glass bottle of water and why frozen water can create bigger cracks in concrete. If you have a liter bottle of ice and a liter bottle of water, then the ice water bottle would be lighter. The molecules are further away from each other at this point than when the water is warmer. Therefore, ice is less dense that water and floats.

When ice melts, the stable crystal structure collapses and is suddenly denser. As water warms past 4 °C, it gains energy and the molecules move faster and further apart. So hot water also takes up more space than colder water and it floats on top of the cooler water because it is less dense. It’s like when you go to a lake to go swimming and the top layer is nice and warm but when you stick your legs below it is suddenly much colder.

Important for our Earth

So why does this even matter? Ice’s buoyancy has important consequences for life on earth. Lakes freeze over on the top in the winter in cold places, which allows fish and other animals to survive below. If the bottom froze, the whole lake could be frozen and almost nothing could survive the winter in the lake. In the northern or southern oceans, if ice sank, the ice caps would all be at the bottom of the ocean, preventing anything from living there. The ocean floor would be full of ice. Additionally, polar ice is important because it reflects light and keeps our planet from getting too warm.

How amber forms — nature’s time capsule

What is amber?

Amber is one of nature’s gems. When a tree is injured, it can create a resin that seals the wound and hardens. Resistant resin that finds its way between layers of sediment fossilizes and becomes hard amber after millions of years. It’s necessary to have exactly the right conditions! Amber is interesting because it can contain creatures and plants from millions of years ago. It has also been used in jewelry for a few thousand years.

Where does amber come from?

You might have thought that amber comes from tree sap. Actually, it is created from resin. The difference is that sap transports nutrients around the tree while resin is semi-solid and acts as a defense response for the plant’s immune system. When the tree has a wound (like a broken branch) or if it is attacked by insects or fungi, it exudes the thick resin that plugs up the injury and prevents further damage. It seals and sterilizes the injury.

Resin dripping from a cherry tree. Image credits: Kreuzschnabel.

When resin is secreted, it’s not certain that it will be turned into amber. More often than not, it gets weathered away. First of all the resin needs to be chemically stable and not degrade over time. It has to be resistant to sun, rain, extreme temperatures, and microorganisms like bacteria and fungi. There are two types of resin produced by plants that can fossilize. Terpenoids are produced by gymnosperms (conifers) and angiosperms. They are composed of ring structures made from isoprene (C5H8) units. Phenolic resins are only produced by Angiosperms. An extinct type of trees called medullosans produced another unique type of resin.

The next factor is that the resin needs to be in the right conditions to fossilize. Young amber could be transported in seawater (it floats), and then buried under sediment to fossilize. In the Baltics, glaciers knocked down many trees and buried them, allowing them to fossilize. Wet clay and sand sediments preserve resin well because they don’t contain much oxygen and the sediments eventually transform into rocks. Intense pressure and temperatures cause the resin to become a solid orange gem. First molecular polymerization forms copal (young amber) and then the heat and pressure drive out terpenes and complete the amber transformation.

Most amber found is about 30-90 million years old, though it’s not sure how long the process to turn resin into amber actually takes. The oldest amber discovered is from the Upper Carboniferous, 320 millions of years ago. Most amber is from pine trees or other conifers, though there are a variety of trees that they can come from. However, most amber is from extinct species because the resin was exuded so long ago.

Perfectly preserved

Amber can be interesting because it can contain pieces of plants, insects, and other creatures. Resin is sticky and liquid, attracting insects because of its sweetness. They get caught in the resin as it hardens and they get preserved. The oldest amber with an organism inside has mites and is from 230 million years ago in north-eastern Italy. Pieces of plants can help identify the source of the amber and insects and other creatures are often perfected preserved which gives information about them. The amber process preserves parts that wouldn’t be preserved through regular fossilization. Amber with remains is also sought after for jewelry because it looks quite nice.

Amber has been used since the stone age (13,000 years) ago in decorations and jewelry. Sold amber can be imitations, the most common are young resins that are not fully formed into amber or stained glass or plastic. A way to know if yours is real is that it should float in saltwater.

An ant inside of Baltic amber. Image credits: Anders L. Damgaard.

Amber can be differently coloured and look in a number of different ways. A light honey colour is typical but amber can range from a white-ish colour to almost black and even blue or red. It depends on the type of tree. Clearer amber is from resin excreted on the bark, cloudier amber comes from the inside of trees.

Amber can be found all around the world. It can be open or underground mined. Most of the world’s extractable amber is found in the Kaliningrad Oblast. Amber has been taken from here since the 12 century. Sometimes amber is washed up from the sea floor and ends up on the beach or collected by diving or dredging. One type of amber called Dominican is a blue colour, and highly prized because it is so rare. It is mined through bell pitting which is dangerous because the tunnels can collapse.

The prized Dominican blue amber. Image credits: Vassil.

Amber is a beautiful stone that takes millions of years to form. Now you can appreciate this fact if you own any amber.