Oceans are frequently polluted by oil from spills, routine shipping, run-offs, and illegal dumping. But what if we could prevent that oil from getting to the oceans in the first place? A group of residents from the town of Brignoles in Southeast France has come up with an innovative recycling scheme using human hair.
The citizens from Brignoles have accumulated 40 tons of hair in a warehouse, sent from salons far and wide. They plan to stuff nylon stockings with it in order to make floating tubes, which they will place near harbors to clean up ocean oil pollution. They have already performed a successful trial in the nearby port of Cavalaire-sur-Mer and have big expansion plans.
Thierry Gras, a hairdresser in Saint-Zacharie near Brignoles and founder of the project Coiffeurs Justes (Fair Hairdressers), explained that hair is lipophilic, meaning it absorbs fats and hydrocarbons. He is now waiting for the project to be approved by anti-pollution and labor officials in order to start large-scale production of the tubes before the end of the year.
The tubes, each around the length of a forearm, can absorb eight times their weight in oil and will be sold at $10.50 apiece. Their manufacturing process starts at the Brignoles warehouse, where hairdressers from all over France, Germany, Belgium, and Luxembourg send their waste hair. It is then sent to a closeny location, where the tubes are manufactured.
“Every day, thousands of hairdressers cut, color, trim and brush your hair. But what happens after? What becomes of these cut hair? What could be its use? How could we add value to this organic matter?,” the website of Fair Hairdressers reads. “You, us, individuals, professionals, citizens, elected officials, communities, we can all act at our level to ensure that this matter is promoted.”
Gras, one of the leaders of the project, told AFP he became interested in fighting pollution when he was a child and heard about the stranding of the Amoco Cadiz tanker off France’s Brittany coast in 1978. Human hair was used back then to mop up the more than 200,000 tons of spilled oil, the first time such an idea was implemented.
He eventually became a hairdresser and was surprised to find out there wasn’t a recycling facility for hair waste, a material that can also be used as fertilizer, isolation material, concrete reinforcement, or in water filtration. Reacting to the news, he came up with the idea of creating hair-filled oil absorbers and founded the Fair Hairdressers association for this purpose in 2015.
The tubes, Gras said, could be used in case of a serious spill, such as the recent one in Mauritius, but the goal is actually to remove micro-pollution on a continuous basis in ports. A dozen tubes are already in use in Cavalaire, soaking up the oil leaked from the engines of the more than 1,000 boats docked in the port.
Exactly why humans lost their fur is unclear, but our skinny exteriors set us apart from most of our mammalian cousins.
Still, us shedding our fur had a dramatic effect on the evolution of our species. To understand why, let’s take a look at what body hair does and see what benefits or drawbacks it brings to the table.
First off, what is it?
Each strand of hair is a filament made out of the protein keratin; when hair grows thickly across an animal’s body, we call it fur.
Hair is a hallmark of mammals, but this family doesn’t have a monopoly on hairs. Insects grow hairs too, although theirs are different in structure from our own. Bees, for example, use it to keep them warm, but also as a sensory organ and to carry pollen. Other species of insects, for example, the fruit fly Drosophila, mostly use them as sensors for tactile (touch) and olfactory (smell) input — a fly’s antennas work similarly to our noses, having a pore to allow smell in and neurons at the base of the strands to sense odors.
Some lichens, algae, plants, and a group called protists can grow trichomes, which is like plant-hair. Trichomes serve a wide range of functions including nutrition, the absorption and retention of water, as well as protection from radiation, insects, or larger herbivores.
And now, fur
Fur consists of an undercoat of finer hairs that helps trap heat, and an outer coat (the ‘guard’) that’s oily and keeps out water.
The most obvious use of fur is to help you keep warm. Animals that produce their own body heat, most notably mammals, use fur as an energy-saving mechanism. A coat of hair traps air around the animal’s body, which provides insulation. Going without one is like always keeping the window open during winter — you can probably keep the place warm, but your energy bill will skyrocket. Evolution doesn’t like paying bills.
Fur protects against damage from the elements or other threats. A hairless animal on a cold winter night could avoid hypothermia but still develop frostbite (because tissues can’t transfer heat fast enough to prevent freezing). In a pinch, fur can also ward off light scratches or bruises, and some animals have water-repellent coats.
The most obvious drawback of having fur is that it costs energy and nutrients to grow. Hairs are renewed constantly to keep them healthy and efficient, and when you’re covered with them, it adds up fast. A 40kg-sheep for example can produce up to 13.6 kg (30 pounds) of wool per year and eats roughly 1.1 kgs of dry food per day (around 400kgs/year), according toSmilingTreeFarm. Its fleece weighs around 3.4% of its total annual intake of food — another way to look at it is that two weeks out of the year, this hypothetical sheep eats only to grow its fur.
Most other drawbacks of fur are dependent on context. Wet fur is a complete liability as it’s heavy and good at trapping water, which will chill you thoroughly. Dry fur is a good insulator but can also make you overheat in hot climates (most mammals apart from primates don’t sweat). Fur is a great home for parasites and creepy crawlies. Shed hairs can create a scent trail for predators to follow — even human hunters look for hairs in the brush when stalking prey.
The hair on our heads still acts as insulation and offers some degree of protection against solar radiation. A testament to its usefulness is that the follicles on our scalps (these are the ‘foundations’ from which hairs grow) have longer active growth periods than any other on our body. The strands of hair on our head can keep growing for years, whereas most others grow for weeks or a few months.
But not all hair grows to keep us warm. Our eyebrows are designed to keep sweat from our eyes, and are thus a product of our lack of fur. We have hair inside our noses, meant to keep out dust and other particles. There are strands of hair inside our ears that allow us to keep balance.
Hair is also meant to help us mate and signal various information to the group. Facial hair for men as well as body and pubic hair for both sexes show maturity. Guys tend to be the hairier of the sexes, and this is a product of testosterone. The most common theory as to why is that it helped keep ancient men warm on those long cold nights out hunting mammoths. But that wouldn’t explain why both sexes have a thin, almost invisible coat of body hair; from experience, I can also vouch that a hairy forearm won’t do much good in winter.
One proposed alternative is that it’s meant to help us feel parasites, and that women tended to favor men who had fewer parasites on them (sounds reasonable). This would have generated an evolutionary pressure for hairier men, as women essentially selected for this trait.
Finally, many species employ hairs as sensory organs. Whiskers are a prime example. They’re academically known as ‘vibrissae’ and come in two forms: the longer, thicker ‘macrovibirssae’ (that animals can typically move voluntarily) and the smaller, thinner ‘microvibrissae’ (which are typically immobile). Whiskers grow in groups on various parts of an animal’s body, most commonly on their snouts, and are used to sweep a wider area using touch. They vibrate when coming in contact with something, and blood vessels at their roots amplify this vibration for the animal to perceive.
If you’re a cat sticking your head in a dark mouse’s hole, having a good set of whiskers can help you find your meal. Spiders are another great example of hair used as sensing organs. They wear their bones (a chitinous exoskeleton) on their outside. Hairs grow out of this skeleton and help transmit vibrations from the soil or web to the animal, acting similarly to hearing or a long-range sense of touch. Note that while mammals grow their fur from keratin, insects use chitin.
So why don’t we have fur?
You might be surprised to hear that humans and other primates have virtually the same density of hair follicles (and thus, hairs) over most of their body. The difference is that ours is ‘vellus hair‘, so short and fine that it’s almost invisible. So it’s not that we lost our body hair, we just changed its type.
We don’t really know why this happened. We have several theories, though.
One of them is that, as our ancestors moved down from the trees, they also discovered seafood. Since wet fur isn’t effective, this could have favored individuals with less fur. However, this isn’t regarded as the likely reason, or at least not the main one.
A more widely-accepted theory is that our ancestors needed to better control their temperature as they switched from living in forests to living in the savannah. No fur meant they could sweat more, preventing heat exhaustion. This may have directly underpinned the success of our species by allowing us to outlast, and thus capture, prey.
Our largest departure from the primate family in regards to our skin comes from our sweat glands. Humans have up to ten times as many eccrine (sweat) glands than chimps or macaques. We also have extremely few apocrine glands, which produce an oil-like substance. Our primate cousins can have equal parts eccrine and apocrine glands and other animals such as dogs will only have apocrine glands on their body and eccrine ones on the pads of their feet or other hairless areas.
The truth is probably somewhere in the middle, and our hairlessness was caused by several factors working together. Environmental pressures and a selective advantage during hunts started the process, and human ingenuity (which means fires and clothes to keep warm) kept it going up to today. However, the heavy presence of sweat glands on our skin suggests that thermoregulation (keeping our bodies’ heat just right) was a major advantage of our hairless outsides.
Keep in mind that there are still many unknowns regarding our hairlessness. But two moments in our evolutionary history could have started this transition.
The first was in our very ancient past, as our furry ancestors climbed down from the trees. Humans have never been too physically imposing, and our ancestors were probably similar in this regard. The theory goes that they focused their activity during the hottest parts of the day in order to avoid predators (who would be hiding from the sun and avoiding activity), which made it advantageous to sweat and made fur impractical. This likely took place around four to seven million years ago. Essentially, in this scenario, it was our efforts to avoid being eaten that lost us our fur.
The second possibility is that humanity needed to shed the hairs in order to be able to hunt. Again, our bodies are very tiny and fragile compared to most wildlife. We’re slower than most animals we’d like to hunt, have no fangs, no claws, and can’t roar. We had tools, maybe spears, to help, but they couldn’t make up all the difference.
However, what our ancestors (and call center operators) can tell you is that you can accomplish a lot if you just tire your competition out. Persistence hunting was one of the few ways our ancestors could acquire large quantities of meat apart from maybe scavenging (which is dangerous and not very lucrative).
Despite our many shortcomings, humans are the best persistence hunters on the planet (or at least among the top ones) simply because we can sweat and cool down even while running. Our ancestors figured out that they didn’t need to fight and stab the antelope; they could just scare it away and chase it, tire it out so that it couldn’t fight back. And then stab it — safely.
This scenario would be more recent — around two million years ago — as hominins like Homo erectus (the first bipedal hominin) started hunting. Bones with tool marks discovered at Homo erectus sites show that they were hunting and butchering large prey regularly. Their bone structures suggest they could walk and run much better than earlier hominins due to longer legs, a foot structure more adapted to walking upright, and larger butt muscles. In this scenario, it was our efforts to catch and eat other animals that cost us our furs.
We may never know for sure why our skin is pink and bare when all our relatives are furry. Personally, I find “because it helped our ancestors survive, somehow” to be a satisfying answer. What I do find more interesting to ponder, however, was whether the way our ancestors wanted to live made fur obsolete, or whether they lost their coats first and then just tried to make the most of it.
Wherever the answers may lie, I’m pretty happy to be a skinny ape; especially as I pick clumps of my cat’s fur from the floor.
You can tell a person has an unhealthy diet if they look overweight, but there are other subtler giveaways. The food we eat is broken down by the body for energy, and traces of it can build up to form a long-standing record of our diet. For instance, to grow hair, the body uses amino acids from the protein we consume, preserving chemical traces of the food. Consequently, the things you can learn about someone’s life just by studying a single strand of hair might surprise you.
A new study led by researchers at the University of Utah shows that hair can be used to tell if a person is vegetarian or prefers hamburgers. What’s more, a person’s diet is strongly correlated with their socioeconomic status. So much so that researchers were able to accurately predict how much a person paid for a haircut based on the chemical analysis of their hair.
You are what you eat
For decades, Jim Ehleringer and Thure Cerling have been refining methods that assess mammal diets from their hair. Their work is based on dietary research that involves the isotopic composition of human bone, which first started in the 1970s.
Archaeologists who were keen on reconstructing ancient diets began to notice that radiocarbon dates on the remains of certain plants such as maize were offset from dates for other plant remains, although they belonged to the same site. They eventually came to the conclusion that this discrepancy is due to maize having a different photosynthetic pathway than most other plants. Consequently, maize has a different relative quantity of the isotopes carbon-14 and carbon-13 in its tissues. Isotopes are atoms with the same number of protons but different numbers of neutrons.
Later, observations revealed that nitrogen isotope ratios can also vary between different food sources, particularly marine versus terrestrial, and stable isotope analysis for human bone quickly became a widely embraced technique among scientists.
These different isotopes present in our food not only build up in the bone but also in the hair.
In a 2008 study, Ehleringer and Cerling showed that the isotopic composition of a person’s hair could trace their travels, by virtue of the fact that water varies in oxygen and isotope ratios according to geography. Naturally, they began to wonder what they could learn from carbon and nitrogen isotopes found in hair.
“Thure Cerling and I have had a long-term interest in exploring how stable isotopes in animal tissues (hair, teeth) and foods record diets. The extension in our research to humans over the last several decades is a natural progression from our ecological studies,” Ehleringer told ZME Science.
A person who eats meat will also ingest the carbon and nitrogen isotopes of the animal feed of the livestock. Corn belongs to a group of plants with a distinct photosynthetic pathway known as C4. Meanwhile, legumes and vegetables belong to C3 plants. Consequently, it is possible to distinguish between meat-eaters and vegetarians, as well as the quality of food, from their hair alone.
The researchers collected hair samples from barbershops and hair salons in 65 cities across the United States. The sampling also included 29 ZIP codes in the Salt Lake Valley in order to zoom in on a particular region. All in all, samples from nearly 700 people were collected.
“One of the rewarding aspects was seeing that barbers gladly allowed us to get hair samples from trash bins, once they learned more about how hair isotopes might relate to the health of their patrons,” Ehleringer said.
The results not only reflect a person’s diet and subsequent health, the researchers also found that the carbon isotope values correlated with the cost of living for the ZIP codes. Individuals who live in areas with a lower socioeconomic status had more corn-like isotope signatures in their hair. In fact, the carbon isotopes in the hair correlated strongly with the average cost of a haircut at the sampling location.
“The results suggest that there are large differences in the amount of protein derived from plant sources versus animal sources. And these differences are associated with socioeconomic status at both local and national scales. Given that the health community has published several large studies in the last few years (cited in the publication) showing that consumption of animal-derived protein is associated with greater health risks, our easy-to-use stable isotopes in hair approach provides a means for community-scale assessments that are free of the more typical survey-based approaches. The increased health risk is likely associated with the fats contained within animal-derived protein foods. Our hope is that the health community would consider this kind of assessment in their efforts to obtain large-scale patterns and an understanding of how these patterns change over time. The analysis cost is less than $10, making it affordable for health-related studies,” Ehleringer said.
The researchers went a step further and also correlated isotope ratios with obesity rates, drawing further connections between diet, socioeconomic status, and overall health.
These results show that hair can be a reliable and objective measure for assessing a community’s health that is not biased by self-reporting.
“One of the great problems in our society is nutrition. Thure Cerling and I have been collaborating for many years and some of our early projects on animal and human hair showed that individual diet histories could be obtained using stable isotopes in hair samples. In North America (but not Europe) meat has a very different carbon ratio than vegetables, and nitrogen isotopes also differ (in both North America and Europe). So our motivation was to use the tools that we have to see if we can make a contribution to this societal problem. This non-invasive approach allows those interested in overall human health to quickly obtain community-level, regional, and temporal assessments,” Ehleringer concluded.
A new study reports that stress does indeed gray out your hair. The good news, however, is that it will also revert to its original color after the stress is removed.
While the paper hasn’t yet been published in a scientific journal, and as such has not yet been peer-reviewed — so take the findings with a grain of salt.
Folk wisdom has held that stress can lead to hairs turning gray. But what we’ve always known intuitively, and through our grandmothers’ rants, seems to be rooted in scientific fact, according to a new study.
The team aimed to investigate how melanin and other proteins in strands of hair interact to create its natural color. They collected around 400 samples of hair from various areas of the bodies of 14 volunteers and analyzed them using an imaging technique designed to detect pigment levels in different parts of the strands.
Some of the hairs thus investigated were gray at the tips rather than the roots, the team explained. Given that strands of hair grow from the root up, this suggests that the hair was gray to begin with but returned to its natural colors at a later date.
Following this realization, the authors called the participants back to answer some questions. First, they calculated when the hairs turned grey and how long had passed since they reverted to their natural color (because hair grows at a constant rate). Then, they asked the volunteers if they had experienced any stressful events around that time, finding several matches.
For one person, the time when their hair returned to its natural color coincided with vacation, suggesting that it was a drop in stress levels that promoted this shift. They do note, however, that only hair that turned grey due to stress will revert to its colors when mental state improves. However, they also explain that this shift back only seems to occur if the drop in stress occurs relatively soon after the hair turned grey.
As I’ve already mentioned, the study has not been peer-reviewed yet, so we don’t yet know the validity of these findings. But they do align well with folk wisdom and anecdotal evidence, so they could hold a kernel of truth.
The study “Human Hair Graying is Naturally Reversible and Linked to Stress” has been published in the pre-print journal bioRxiv.
A certain subtype of schizophrenia could be diagnosed based on biomarkers in a patient’s hair, a new study found.
The team at the RIKEN Center for Brain Science (CBS) in Japan reports that a certain subtype of schizophrenia is related to very high levels of hydrogen sulfide in the brain. This mutation, caused by a DNA-modifying reaction during development, can also be detected by analyzing biomarkers in a patient’s hair.
A headful of markers
“Nobody has ever thought about a causal link between hydrogen sulfide and schizophrenia,” says team leader Takeo Yoshikawa, the paper’s corresponding author.
“Once we discovered this, we had to figure out how it happens and if these findings in mice would hold true for people with schizophrenia.”
The best way to diagnose a condition is to have a reliable, objective marker you can look for or compare a patient against. For schizophrenia, the most reliable such marker in use is an abnormal startle response test (the link between schizophrenia and abnormal startle responses has been documented since around 30 years ago).
Humans aren’t normally startled by a random burst of noise if it’s preceded by a smaller one — this latter one is called a prepulse. The whole phenomenon is known as prepulse inhibition (PPI); in people with schizophrenia, PPI is lowered, meaning such patients don’t experience a dampened startle response after the prepulse (or experience much lower dampening than normal). Because it’s pretty reliable and consistent, the PPI test is a strong tool used in diagnosing schizophrenia, even if it doesn’t tell us very much about the biology behind the condition.
The RIKEN CBS team set out to look for differences in protein expression between strains of mice that had either very low or very high PPI. They found that one protein (Mpst) was expressed much more in the brains of mice with low PPI than in those with high PPI. Knowing that this enzyme is involved in the synthesis of hydrogen sulfide, the team measured the concentration of this compound in the hairs of low-PPI mice — they found elevated levels.
To validate the findings so far, the team engineered some of the low-PPI mice in order to reduce the expression of the MPST gene (which governs the Mpst protein) — this helped make the mice behave more closely like their healthy kin. Next, the team established that MPST gene expression was higher (postmortem) in the brains of people with schizophrenia compared to healthy controls. The level of MPST protein seen in the brains also correlated well with the severity of the symptoms each patient experienced, they add.
After establishing that MPST expression can be used as a biomarker for schizophrenia, the team examined hair follicles from over 150 schizophrenia patients. The findings so far held firm: all of them had much higher expression of MPST mRNA than people without the condition. The results weren’t perfect, the team explains — which indicates that sulfide stress does not account for all cases of schizophrenia — but they did show that MPST levels in hair are a reliable biomarker for the disease, and can be tested before other symptoms become apparent.
Testing on postmortem mice’s brains showed that the high MPST levels were associated with changes in DNA that lead to permanently altered gene expression. The team hypothesized that inflammatory stress during early development might be the root cause (hydrogen sulfide can protect against inflammatory stress).
“We found that anti-oxidative markers—including the production of hydrogen sulfide—that compensate against oxidative stress and neuroinflammation during brain development were correlated with MPST levels in the brains of people with schizophrenia,” says Yoshikawa.
“Currently, about 30 percent of patients with schizophrenia are resistant to dopamine D2-receptor antagonist therapy. Our results provide a new principle or paradigm for designing drugs, and we are currently testing whether inhibiting the synthesis of hydrogen sulfide can alleviate symptoms in mouse models of schizophrenia.”
The paper “Excess hydrogen sulfide and polysulfides production underlies a schizophrenia pathophysiology” has been published in the journal EMBO Molecular Medicine.
Despite an immense scientific and commercial interest, halting and reversing hair loss hasn’t been truly possible — until now. In a new series of studies, a U.S. startup claims it has developed a way to clone hair follicles using stem cells derived from a person’s own cells (i.e. not fetal). A 3-D printer is used to generate a Jell-O-like mold which holds the follicles in place for the hair to grow. In the future, this procedure — which so far has only been tested on mice — could form the basis for truly regenerative hair treatment.
The hair restoration market crossed $5 billion in 2017 and is expected to witness more than 25% compound annual growth rate from 2018 to 2024. This phenomenal market growth isn’t all that surprising considering the number of people affected by pattern hair loss. According to the American Hair Loss Association, two-thirds of men will begin to see their locks lose some of their luster by age 35. At age 50, about 85% of men will have experienced a significant amount of thinning. And although pattern baldness is generally thought of something that affects mostly men, women are no strangers to it. In fact, an estimated 40% of individuals affected by hair loss are female.
Today, commercially available hair restoration treatments mostly consist of the surgical transplantation of hair follicles. The procedure, which costs around $10,000, involves moving hair from one part of the scalp to another. The problem with this procedure is that a person is limited by the amount of available hair. Sometimes, hair from the back or armpits can be transplanted, but the result may turn out to be less-than-aesthetically pleasing.
One solution to his predicament is cloning a person’s hair follicles — this way you’d truly have an unlimited supply of hair.
Human hair grown on the back of a mouse. Credit: Sanford Burnham Prebys.
According to The Atlantic, Stemson Therapeutics, a San Diego-based startup, has developed an innovative therapy that clones hair follicles from stem cells and implants them around a person’s dormant follicles. The stem cells are derived from a person’s own cells, such as skin or blood, and do not involve fetal stem cells. Since a person’s own cells are used, there’s little risk that the immune system will reject the transplant.
The company’s findings were recently presented at the annual meeting of the International Society for Stem Cell Research, where researchers shared images of tufts of hair growing from the back of a mouse. It may not look very impressive but as a proof of concept this a huge leap forward in regenerative medicine.
The researchers had to overcome a number of challenges. Other groups have tried to clone hair but eventually failed because, over time, the stem cells would stop producing hair. The American researchers solved this problem by culturing cells together in a teardrop shape so they continue to signal each other, rather than letting them spread out. The shape of the follicle is also critically important, otherwise, cloned hair can grow inward or sideways instead of sprouting through the skin outward. In order to grow hair follicles that hold their shape, the startup partnered with researchers at Columbia University to produce a 3-D printing mold that holds the follicles and dermal papillae together.
For both men and women, hair loss can cause considerable emotional damage, including loss of self-esteem and confidence. Before you get too excited, there are some caveats. This research is still preliminary and we might be still many years away from having this treatment ready for human use. And when it will become available, expect it to be quite expensive — at least at first. Growing new hair, follicle by follicle, sounds like a cumbersome procedure that ought to cost at least as much as conventional hair transplant surgery.
The same set of genes that gives mammals hair and birds feathers helps the pufferfish grow spines.
Image credits Kevin Yi.
While the spines that cover pufferfish are readily apparent, how they got to be there isn’t. New research, however, has identified the genes responsible for the evolution and development of these striking skin ornaments, finding that the process is similar to how other vertebrates get their hair or feathers.
“Pufferfish are some of the strangest fish in the ocean, particularly because they have a reduced skeleton, beak-like dentition and they form spines instead of scales — not everywhere, but just in certain patches around the body,” says corresponding author Gareth Fraser, an Assistant Professor at the University of Florida.
“It just blows me away that regardless of how evolutionarily-different skin structures in animals are, they still use the same collection of genes during development.”
Fraser and his team analyzed the development of the spines in pufferfish embryos. Initially, they expected to see them form from scales, in essence, that some of the scales themselves would morph into the spines. However, what they found was that the spines’ development is independent of that of the scales. In addition to this, they identified the genetic network that underpins the development of the scales, and it’s the same one that governs hair and feather formation in other vertebrates.
After identifying these genes, the team decided to block some (CRISPR-Cas9 and other genetic techniques) that are classic markers of skin appendage development to see what would happen. This approach allowed the researchers to reduce the number of spines that grew on pufferfish, and make them ‘sprout’ in more varied places around their body. Normally, the spines are localized to specific areas on the pufferfish where they can offer the most protection, Fraser explains.
“When pufferfish inflate by ingesting water or in some cases air, their skin becomes stretched, especially around the abdomen and is more susceptible to damage, such as being torn,” he says. “Spines reinforce the puffed-up abdomen. In extreme cases, some pufferfish have lost all other spines on their body and retain only the abdominal spines.”
The diversity seen in spine location among pufferfish is likely the result of different ecological pressures, he adds. Different morphological set-ups of spines may allow pufferfish to access new ecological niches. “As the climate changes and environments become different, pufferfish may use these evolving traits to tolerate and adapt to change,” Fraser says. Ultimately, him and his team hope to identify the genetic differences that create the wealth of diversity in spine layout and morphology.
“We can manipulate different things associated with pufferfish diversity, which gives us clues about the function of genes that are necessary for normal development and helps us understand the evolution and patterns of pufferfish spines.”
“Pufferfish are wildly-derived fish that are incredibly different from other groups, and ultimately, we want to see if there’s something specific to the genome of the pufferfish that can provide clues to suggest mechanisms that allow them to create these weird structures.”
The paper “Evolution and developmental diversity of skin spines in pufferfishes” has been published in the journal iScience.
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.
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) 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.
Scientists at the National Institutes of Health and the University of Alabama at Birmingham found a link between graying hair in mice and the activation of the innate immune system. Specifically, the authors of the new study identified a connection between genes associated with hair color and genes that sound the alarm in the event of a pathogenic infection. The findings might explain why some people’s hair turns gray in response to chronic stress or some serious illness.
Our hair is colored thanks to melanocyte stem cells found in the hair follicle. When old hair falls, leaving room for new hairs to grow, the melanocyte stem cells serve as a reservoir of melanocytes — cells that produce a pigment called melanin. Without these stem cells, hair simply grows unpigmented, gray-colored.
Melissa Harris, Ph.D., assistant professor within the Department of Biology, along with colleagues at UAB, studied the genetic modifiers of hair graying in mice but also performed a transcriptomic analysis of melanocyte stem cells. This way, the team of researchers found a link between the transcription factor MITF and innate immunity.
MITF has a role in regulating the functions within melanocytes. One of these roles is keeping interferon response in check. Interferons are signaling molecules which are produced by cells when they detect a foreign invader. Interferons then signal to other cells to express the genes that inhibit viral replication. When MITF’s control of the interferon response was lost in the melanocyte stem cells, the mice’s hair turned gray. What’s more, in an experiment with mice that are predisposed for getting gray hair, when the innate immune signaling was activated, the number of gray hairs increased.
“Our lab uses some pretty cool genomic tools to take a broader look at how our cells change the way they function under different conditions. We focus on gene expression, and it used to be that we would have to focus on looking at one gene at a time, or a handful of genes. Now we can ask how the whole system changes its gene expression in one fell swoop. And sometimes this leads to discoveries that you do not expect! For instance, in this story, the fact that MITF represses the expression of interferon-stimulated genes. With our current day genomic tools, you don’t have to be limited by your own imagination!” Harris told ZME Science.
Credit: PLOS Biology.
The findings suggest that the same genes that control pigment in hair and skin also control the immune system, possibly with important consequences in medicine. For instance, the connection might help researchers understand pigmentation diseases like vitiligo, which causes discolored skin patches and affects 0.5-1% of the population.
“For melanocyte-related disorders, we think this discovery will be relevant to our understanding of the autoimmune hypopigmentation disorders, vitiligo, and to the melanocyte-specific cancer, melanoma. Many vitiligo researchers have already speculated a role for innate immunity in the etiology of vitiligo, and this is just another step towards identifying mechanisms that could initiate vitiligo. In regards to melanoma, our studies could provide one example of how melanoma cells could mediate immune evasion. It’s become pretty well appreciated that tumors can evade immunosurveillance. If melanoma cells take advantage of the fact that MITF can repress aspects of the immune response, then this may contribute to their ability to ‘hide’ from the protective effects of our immune system,” Harris said.
It may also be possible that the findings can explain why some people experience premature graying of their hair as a result of illness or stress. The researchers aim to address this question in future studies.
“We would love to test whether the mechanism in this study could explain those anecdotal stories where people experience premature gray hair. Could the combination of a genetic predisposition and an every-day viral infection be just enough to negatively affect the melanocytes and melanocyte stem cells in humans, and cause early hair graying?” said Harris.
Scientific reference: Harris ML, Fufa TD, Palmer JW, Joshi SS, Larson DM, Incao A, et al. (2018) A direct link between MITF, innate immunity, and hair graying. PLoS Biol 16(5): e2003648. https://doi.org/10.1371/journal.pbio.2003648.
Scientists have identified a group of 124 genes that direct human hair pigmentation. While previous studies have shown that this feature is genetically controlled, it’s the first time the specific genes have been pinpointed. This could not only allow us to better understand our own genome but it could also shed new light on skin, testicular, and ovarian cancer, as well as several other diseases.
Image credits: Derek Gavey.
We might not think about it too often, but hair plays a key role in our physical appearance — okay, who am I kidding: everyone knows of that. Hair color (like skin color) is determined by two types of melanin. We already knew that melanin production and distribution have an overwhelmingly heritable nature (genetics accounts for almost 97% of color variation), but we didn’t know which genes were responsible. Now, Pirro Hysi, Manfred Kayser, and colleagues, believe they’ve found the answer.
The scientists have analyzed DNA data from almost 300,000 people of European descent, including people with black, blonde, dark brown, light brown or red hair. By comparing their genetic information with their hair color, they were able to identify the genes responsible for hair pigmentation, including 100 were not previously known to influence pigmentation. Joint lead author Professor Tim Spector from King’s College London said:
“Our work helps us to understand what causes human diversity in appearance by showing how genes involved in pigmentation subtly adapted to external environments and even social interactions during our evolution. We found that women have significantly fairer hair than men, which reflects how important cultural practices and sexual preferences are in shaping our genes and biology.”
Interestingly, the work would have application in other fields, as some of the genes found to influence pigmentation are connected to several types of cancers, and others are related to Crohn’s and other forms of bowel disease.
“This work will impact several fields of biology and medicine. As the largest ever genetic study on pigmentation, it will improve our understanding of diseases like melanoma, an aggressive form of skin cancer,” Spector adds.
Additionally, the findings could also be useful in forensic analysis — aside from improving our understanding of human pigmentation genetics, they pave the way for more accurate hair color prediction tests from DNA samples. In other words, forensic scientists might one day be able to tell someone’s natural hair color based on DNA alone.
So far, researchers are very good at accurately predicting black and red hair, but blonde and brown hair are proving more challenging. The team also reports that, on average, women seem to have lighter hair than men, which suggests an association between sex and hair color.
The study “Genome-wide association meta-analysis of individuals of European ancestry identifies new loci explaining a substantial fraction of hair color variation and heritability” has been published in Nature.
People have been going to the dentist for a much longer time than you’d believe. Archaeologists working in northern Italy have found the oldest known dental fillings. They were made from a mix of bitumen, hairs, and plants some 13,000 years ago.
Image credits Stefano Benazzi.
There’s no such thing as a good toothache. That’s why we have dentists, and that seems to have been the case in the stone age, too — although I hear conditions weren’t as good back in the day. Faced with a lack of materials, tools, or you know, any sort of body of literature to guide their steps, ancient dentists had to be creative (they invented a lot of stuff back then). A pair of 13,000-year-old front teeth found in Italy stands testament to what they could achieve with a bunch of stones and bitumen.
The teeth were discovered in the Riparo Fredian site near Lucca, northern Italy. Each one has a large cavity going from the surface all the way through to the pulp. They were probably hollowed out and enlarged with stone tools, judging by microscopic etches and markings on their walls. While poking though these holes, a research team lead by Gregorio Oxilia from the University of Bologna has found residues of bitumen with plant fibers and hairs mixed in. Although very different from what you’d see in today’s fillings, their purpose was probably the same — keep stuff away from the pulp and keep pain to a minimum.
“It is quite unusual, not something you see in normal teeth,” Stephano Benazzi, an archaeologist at the University of Bologna and corresponding author of the paper told New Scientist.
Benazzi noted that the etchings found in these teeth are similar to another set him and the team found in Italy in previous research. That set of teeth was dated as 14,000 years old, the oldest known evidence of dentistry we’ve ever seen. But this is the (new) first time we know of fillings being used.
Image credits Gregorio Oxilia.
It’s probable that the Paleolithic dentist drilled out the cavities and then filled them in — just like his modern counterparts would do. However, he only had tiny stone tools to drill with, probably no anesthetics, and bitumen to use for the fill. The team is unsure as to why the hairs and plant fibers were added to the mix (they did rule out the possibility of them being remains of food since they were added to the area after drilling). One theory is that the plants were chosen for their antiseptic properties, helping to keep the cavity healthy and clean of bacteria. Or the dentists thought fibers would help fix the filling. We don’t yet know.
What’s really striking is the time-frame of the fillings. They’re evidence of relatively advanced knowledge being put to use in fixing an ailment thousands of years before we though they’d become a significant affliction — the change in diet agriculture brought on is thought to have lead to a dramatic increase in cavities. Still, at this time Europe was seeing a lot of people migrating in from the near East, Benazzi adds. The foods they introduced to the continent may have led to more cavities, and then to dentistry.
The full paper “The dawn of dentistry in the late upper Paleolithic: An early case of pathological intervention at Riparo Fredian” was published in the American Journal of Physical Anthropology.
A study from the Stanford University School of Medicine has found that certain protein levels determine whether you’re a blonde or a brunette.
For the first time, the molecular basis for one of the most important physical human traits was described, outlining that even the tiniest DNA changes could have a crucial impact on our genome, which has possibly affected the evolution, the migration and even the course of the history as we know it today. David Kingsley, PhD and expert in developmental biology, declared that:
‘We’ve been trying to track down the genetic and molecular basis of naturally occurring traits — such as hair and skin pigmentation — in fish and humans to get insight into the general principles by which traits evolve, and now we find that one of the most crucial signaling molecules in mammalian development also affects hair color.’
A protein called KITLG, commonly known as a stem cell factor, was found to be encoded in the genes whose expressions are regulated in the DNA. Turns out that a single change in the DNA according to this biological procedure is responsible for major physical traits, such as the predominantly blond hair of Northern Europeans. This change was found to affect only the level of KITLG in hair follicles.
Another result of the study concerns the tissue-specific, small changes in the expression of genes, whose effect can be morphologically noticeable. Connecting specific DNA changes with specific clinical prototypic outcomes is clearly laborious, as the study conducted by David Kingsley and led by Cathrine Guenther (PhD) underlines. To be more specific, the change is called ‘subtle’ because it occurs over 350, 000 nucleotides away from the KITLG gene itself and its impact on the amount of gene expression is no bigger than 20 percent. The procedure involves replacing an adenine (a single nucleotide) by a guanine on human chromosome 12 and its impact is believed not to be significant, taking into consideration that, when it comes to gene expression, the scale is only referred to as ‘on’ or ‘off’.
Adaptive changes are often the result of variations in the level of regulatory regions controlling gene expression and not necessarily within the coding regions of the gene itself. His explanation of the result is that:
‘in this case, it controls hair color. In another situation, perhaps under the influence of a different regulatory region, it probably controls stem cell division. Dialing up and down the expression of an essential growth factor in this manner could be a common mechanism that underlies many different traits.’
According to the researchers, there were a number of clues leading to the fact that the regulatory regions could be of increased importance in deciding the hair color, such as that (1) the adenine-to-guanine nucleotide change was already associated with blond hair color in Northern Europeans due to previous genome-wide studies and (2) the large mutation in lab mice (called inversion) usually affects multiple nucleotides near the KITLG gene, given the fact that the mice with two copies of the mutation, one for each chromosome, are white, while the ones with a single copy of the mutation are significantly lighter, as we previously explained.
‘Because this nucleotide switch only effects the KITLG expression by about 20 percent or so, it would have been difficult to believe it would have such an effect on hair color. For that we needed these very carefully constructed, well-controlled animal models. They clearly showed us that this small difference in expression is enough to switch hair color in these animals.It’s clear that this hair color change is occurring through a regulatory mechanism that operates only in the hair. This isn’t something that also affects other traits, like intelligence or personality. The change that causes blond hair is, literally, only skin deep.’
It seems counter-intuitive but weight-for-weight, a strand of human hair is comparable in strength to steel. It’s also elastic, being stretchable one and a half times its original length before breaking. These properties have attracted interest in a new class of materials that mimic hair. Now, a group from the University of California San Diego have finally found out what makes hair so strong and suggest a body armor made from synthetic hair as a first application.
“Nature creates a variety of interesting materials and architectures in very ingenious ways. We’re interested in understanding the correlation between the structure and the properties of biological materials to develop synthetic materials and designs — based on nature — that have better performance than existing ones,” said Marc Meyers, a professor of mechanical engineering at the UC San Diego Jacobs School of Engineering and the lead author of the study.
Meyers and colleagues put single strands of human hairs to deformation and compression tests. Examining the hairs as they deformed or stretched at the nanoscale level revealed they behave differently depending on how fast or slow they’re stretched. The fast hair stretches, the stronger it is, which is analogous to how honey behaves, Meyers said.
“Think of a highly viscous substance like honey,” he explained. “If you deform it fast it becomes stiff, but if you deform it slowly it readily pours.”
Hair is essentially made of two main parts: the cortex, made of parallel fibrils, and the matrix, comprised of an amorphous (non-ordered, random) structure. It’s the matrix that’s sensitive to the speed of deformation while the cortex is not. It’s these two properties combined that lend hair the ability to withstand high stress.
That’s not all. The cortex fibrils are each made of thousands of spiral-shaped chains of molecules called alpha helix chains. When hair is deformed, these chains uncoil and turn into sheet structures. According to the UC San Diego researchers, this structural change allows hair to handle a large amount of deformation without breaking, as reported in the journal Materials Science and Engineering.
Another interesting fact about hair deformation is that it’s partly reversible. If you stretch a strand of hair under a small amount of strain, it will recover to its initial shape. Stretch it further, though, and the deformation becomes irreversible.
Next, the team plans to study why water has such a strong influence on human hair properties. For instance, washing hair causes it to revert to its initial shape.
“Since I was a child I always wondered why hair is so strong. Now I know why,” said Wen Yang, a former postdoctoral researcher in Meyers’ research group and co-author on the paper.
Researchers from Lawrence Livermore National Laboratory developed a new test which uses unique protein markers in the hair to identify humans. The hair protein is far more stable and lasts longer than DNA which means it could not only be useful in criminal investigations but archaeological ones as well.
Information encoded in proteins of human hair
“Human identification from biological material is largely dependent on the ability to characterize genetic polymorphisms in DNA. Unfortunately, DNA can degrade in the environment, sometimes below the level at which it can be amplified by PCR. Protein however is chemically more robust than DNA and can persist for longer periods. Protein also contains genetic variation in the form of single amino acid polymorphisms. These can be used to infer the status of non-synonymous single nucleotide polymorphism alleles.” the researchers wrote in PLOS ONE.
Glendon Parker and colleagues tested the effectiveness of hair protein as an identification marker for 66 European-American subjects, 10 subjects with African ancestry, and also six archaeological skeletal remains which were up to 260 years old.
They have found a total of 185 hair protein markers to date. That’s more than enough to provide a unique pattern that would distinguish a person among a population of one million, the researchers wrote. However, criminal investigations require no room for interpretation or error, so Parker and team hope to identify a core set of around a hundred protein markers which should be sufficient to distinguish an individual among the entire world’s population.
“We are in a very similar place with protein-based identification to where DNA profiling was during the early days of its development,” said LLNL chemist Brad Hart, the director of the Lab’s Forensic Science Center and co-author of a paper detailing the work. “This method will be a game-changer for forensics, and while we’ve made a lot of progress toward proving it, there are steps to go before this new technique will be able to reach its full potential.”
DNA can be recovered from hair roots, but not that often. Seeing how hair is one of the most common pieces of evidence perpetrators leave at a crime scene, hair protein identification might be a game-changer in law enforcement.
The main problem in this case isn’t the printing itself, but rather the required processing power. Computation time can be huge when it comes to fine details, and the power demand is also considerable. Now, researchers at MIT’s Media Lab have found a way to bypass a major design step in 3-D printing, creating efficient models and printing thousands of hair-like structures.
The main innovation was giving up on conventional computer-aided design (CAD) software to draw thousands of individual hairs on a computer, a process which would take hours to compute, instead building a different software platform.
Their new platform, “Cilllia,” lets users define the angle, thickness, density, and height of thousands of hairs, in just a few minutes. They used it to design arrays of hair-like structures with a resolution of 50 microns — about the width of a human hair. They toyed around with the size, demonstrating that their solution has the flexibility to create arrays ranging from coarse bristles to fine fur, onto flat and also curved surfaces, and all this using a conventional 3D printer.
Jifei Ou, a graduate student in media arts and sciences and the lead author of the new paper, was thrilled.
“It’s very inspiring to see how these structures occur in nature and how they can achieve different functions,” Ou says. “We’re just trying to think how can we fully utilize the potential of 3-D printing, and create new functional materials whose properties are easily tunable and controllable.”
The technique itself is not extremely complicated. The hairs are simply designed as cones, with fewer and fewer pixels the higher you go. To change the hair’s dimensions, such as its height, angle, and width, you simply change the distribution of the pixels. This also makes the whole thing much more scalable.
After this step was done, printing the hairs on a flat surface was quite easy, but printing on curved surfaces proved much trickier. That obstacle too was overcome.
“With our method, everything becomes smooth and fast,” Ou says. “Previously it was virtually impossible, because who’s going to take a whole day to render a whole furry rabbit, and then take another day to make it printable?”
The potential applications are considerable, ranging from toys to sensors. The team demonstrated the former by creating a toy rabbit, but the latter is probably more interesting.
“The ability to fabricate customized hair-like structures not only expands the library of 3-D-printable shapes, but also enables us to design alternative actuators and sensors,” the authors conclude in their paper. “3-D-printed hair can be used for designing everyday interactive objects.”
Dandruff is the most common scalp condition, yet we know surprisingly little about it.
Microscopic image of dandruff.
Over 100 years ago, French microbiologist named Louis-Charles Malassez noticed a fungus — which he dubbed Malassezia — on the scalps of people who had dandruff. He suggested a correlation – the fungus lies at the base of the hair, causing the itch and the white flakes we know so well. The correlation was mostly accepted and has stuck as popular knowledge, but that idea is starting to be challenged.
In a study of 363 adults with and without dandruff, Zhijue Xu from the Shanghai Jiao Tong University in China and his team have discovered that dandruff is more closely linked to the presence of Staphylococcus bacteria on the scalp than a fungus. In fact, they found no difference between dandruff and dandruff-less people when it comes to the fungus. But when it comes to the bacteria, it’s a completely different picture.
People with dandruff had higher amounts of Staphylococcus, and much smaller amounts of a different type of bacteria, Propionibacterium, than those without dandruff. So it may be the presence of the bacteria, but there may also be a combination of other bacteria lacking that causes dandruff. The study reads:
“The dominant fungus (Malassezia species) displayed contrary roles in its contribution to the healthy scalp micro-environment. Bacteria and fungi didn’t show a close association with each other, but the intramembers were tightly linked. Bacteria had a stronger relationship with the severity of dandruff than fungi.”
The study also found that people with dandruff tend to have less water and oily secretions on their scalps than others but the causality was not determined.
“The sebum quantity and water content were negatively correlated with the formation of dandruff and had significant relationships with the two dominant but reciprocally inhibited bacteria on the scalp (Propionibacterium andStaphylococcus).”
If this is true, then not only do antifungal treatments not work for dandruff, but they may even be making things worse.
While the exact causes of dandruff remain unclear and debatable, there are also other factors which we can control. Overuse of hair products, emotional stress, inadequate nutrition and washing your hair too much or too little can create or exacerbate the development of dandruff.
Goosebumps are strange. We get goosebumps when we’re cold, when we’re afraid, and sometimes when we’re really excited – three very different situations. But no matter why we get them, goosebumps are tightly connected to a single hormone: adrenaline.
In humans, goosebumps are strongest on the arms.
The anatomy of a goosebump
[panel style=”panel-success” title=”Goosebumps form:” footer=””]- when you’re cold
– when you’re threatened
– when you’re excited
– as a response to some medications or diseases[/panel]
By definition, goosebumps are “the bumps on a person’s skin at the base of body hairs which may involuntarily develop when a person is cold or experiences strong emotions such as fear, nostalgia, pleasure, awe, admiration or sexual arousal.” We inherited them from our ancestors, passing them on generation after generation, even though their function has been rendered mostly useless.
Each one of our hairs has tiny muscles at the base called arrector pili muscles. Goosebumps are formed whenever these muscles contract as a response to an external stimulus — which is why they are sometimes called “piloerection” (the erection of hairs).
Image via Penn State University.
Goosebumps are a subconscious response to the release of adrenaline; that’s why you can’t get them at will, they happen outside of your control. Adrenaline is a hormone produced by the adrenal glands, located above the kidneys, and some neurons. Adrenaline plays a key role in the flight-or-fight response, by increasing blood flow to muscles, output of the heart, pupil dilation, blood sugar, and giving you goosebumps. Other symptoms of adrenaline include tears, sweaty palms, trembling hands, an increase in blood pressure, a racing heart and the feelings of butterflies in the stomach.
By now, you’re probably wondering what goosebumps have to do with all of these. Well as we mentioned, they’re a subconscious response – it’s something your body does automatically, even if it doesn’t actually help you. But let’s take it one by one.
Goosebumps when you’re scared
When you feel threatened, your body prepares to defend or run away – this is the flight-or-fight response. As is the case with many other mammals, your body is trying to make you seem as large as possible – in this case, by raising the hair on your body, just like a cat does.
“The general principle is, if you are going to be attacked, try to look as big as you can,” says David Huron, a musicologist at Ohio State University.
The idea would be to make the hair on our bodies stand up, thus appearing bigger and more menacing than we actually are. However, nowadays we don’t have as much hair on our bodies as we once had, which means this tactic isn’t really effective, and all we’re left with is the silly looking goosebumps. According to Doctor Richard Potts of the Smithsonian Museum:
“All mammals share this hair raising trait. But humans don’t have enough body hair for the response to make a difference; it’s a vestigial reflex left over from when we had furry coats. “
Goosebumps when you’re cold
Brr! Photo by Ildar Sagdejev.
This is how goosebumps actually emerged. The reaction is believed to take place in the presence of extremely low temperature. The idea was to contract the muscles and make the hairs stand up, creating an isolating layer to preserve bodily heat.
The combination of piloerection and shivering is very effective for maintaining and even increasing body heat in cold environments. The shivering creates muscle contractions which raise the body temperature, and the fur (through goosebumps) acts as a blanket layer, preserving that temperature.
Goosebumps from emotions
This one is probably the most uncertain and least straightforward scenario. We sometimes feel “the hair on the back of our necks standing up” when we’re excited or afraid, even when we’re listening to music. Jaak Panksepp, a Bowling Green State neurobiologist studied how music can give us goosebumps, finding that it’s almost always sad music giving us goosebumps. He believes that some chemicals in the brain connected social loss are the cause here, but it’s still unclear just why our body reacts like this. Either way, this is still a primeval response.
When you’re afraid, but not in any real danger (say you’re watching a scary movie) goosebumps can actually be a part of a pleasurable act. You feel the thrill and the danger from the movie, your body’s primeval instincts kick in, but the conscious part knows you aren’t in any danger and it’s saying “everything is OK” – which can make you feel good.
Sometimes, piloerection can be connected with sexual arousal. Again, the adrenaline rush is the main cause, but we still don’t know for sure why the body reacts this way.
Medications and dietary supplements that affect body temperature and blood flow may cause goosebumps. The same can be caused by a withdrawal from opiates such as heroin, or by health problems such as temporal lobe epilepsy, some brain tumors, and autonomic hyperreflexia.
To conclude, goosebumps are directly connected to an adrenaline rush. They were supposed to either make you seem bigger and more menacing for enemies or protect you from cold – when our bodies were completely covered in hair. However, because they also occur in more complex situations – such as listening to music – there are probably still many things we don’t understand about them.
Creating artificial skin may sound weird, but it can be extremely useful (or even life saving) for people who suffered from burns or any type of similar accident; it is also useful for testing drugs or cosmetic products. Skin transplants are a growing need, and many teams from across the world hope to one day be able to create artificial skin to fulfill that need. This latest attempt from Japan takes us one step closer to that goal: it can create new hairs and even sweat.
A fluorescent protein was used to highlight the area of artificial skin. Credit: Takashi Tsuji/RIKEN
Led by researchers from the RIKEN Centre for Developmental Biology, the team used gum cells from mice, converting them into a new type of stem cell. They then used these cells to build a 3D layer of skin. The artificial skin replicates all the three major layers of skin – the waterproof epidermis which gives our skin tone, the dermis which contains tough connective tissue, hair follicles, and sweat glands, and the hypodermis which is made of fat and connective tissue.
They then transplanted the skin back to hairless mice, where they started to develop normally and integrated fully with the rest of the body.
“Up until now, artificial skin development has been hampered by the fact that the skin lacked the important organs, such as hair follicles and exocrine glands, which allow the skin to play its important role in regulation,” said Takashi Tsuji, who led the new study.
“With this new technique, we have successfully grown skin that replicates the function of normal tissue. We are coming ever closer to the dream of being able to recreate actual organs in the lab for transplantation, and also believe that tissue grown through this method could be used as an alternative to animal testing of chemicals.”
Previously, other teams have tackled the problem from a different angle. Another group has created an artificial skin which can feel pressure and tell your brain about it, offering a realistic sensation. Perhaps the two can be blended together, and we can soon have artificial skin which can feel pressure and also create hair and sweat. The real deal is getting closer and closer.
Journal Reference: Bioengineering a 3D integumentary organ system from iPS cells using an in vivo transplantation model.
Among evidence analyzed during a rape-related crime investigation, one of the best clues that might incriminate a suspect are pubic hair samples. But because these hairs most often than not are missing their roots, it’s very difficult if not impossible to make a conclusive DNA analysis. Silvana Tridico, a forensic biologist at Murdoch University in Perth may have a found a way to use this evidence in an alternate way. She found that it may be possible to identify a rapist based on his signature bacterial culture found in the pubic hair, a find of great significance for forensic investigations.
Bacteria doesn’t lie
Image: Huff Post
Tridico and colleagues asked seven individuals – two of which formed a couple living together – to collect hair from their scalps and pubic area for five months. In the lab, bacterial populations found in the hairs were analyzed after two and five months. Microbial populations were also found, of course: 50 different varieties of microbes in males and 55 in females, yet there were far too many of the microbes that weren’t specific to the individual. The pubic hair bacteria, however, turned out to be more distinct; in addition, each individual’s “personal” pubic bacteria stayed roughly the same during the 5 months. Moreover, more kinds of bacteria live here: 73 in males and 76 in females. The larger the bacterial diversity, the greater the chance of a specific, signature culture based on which identification can be made.
Each person’s pubic hair contained distinct bacterial cultures, yet the two persons living together had a great similarity in the examined cultures. The couple later revealed that they had sexual intercourse 18 hours before the collection of their hairs, which might explain the predicament. The findings appeared in Investigative Genetics.
The sample size is far too small for the findings to be deemed conclusive. DNA matching is considered pretty reliable, but even nowadays there are false positives and – make no mistake – innocent people go to jail because of it. If pubic hair bacterial analysis is ever used in forensic investigations, it needs to become highly predictable and reliable, otherwise the evidence will never hold in a court of law. A couple of the challenges scientists need to identify are how easily the bacteria are transferred between people, and whether these bacteria can be transferred by using the same bed sheets, clothing, or towels and how long transferred bacteria can stay on pubic hairs.
“I think this method has interesting possibilities for forensic science,” says Max Houck, a lead forensic scientist at Consolidated Forensic Laboratory, a government organization based in Washington, D.C. “Forensic science is all about the associations between people, places, and things involved in criminal activities, and sexual assaults are among the closest associations we encounter.”
An ancient Egyptian woman who lived 3300 years ago was found to have no less than 70 hair extensions. This incredibly elaborate hairstyle was probably made especially for her resting place.
Image credits: Jolanda Bos.
Interestingly enough, she wasn’t mummified, her body was simply wrapped in a mat, said Jolanda Bos, an archaeologist working on the Amarna Project.
“Whether or not the woman had her hair styled like this for her burial only is one of our main research questions,” said Bos in an email to Live Science. “The hair was most likely styled after death, before a person was buried. It is also likely, however, that these hairstyles were used in everyday life as well and that the people in Amarna used hair extensions in their daily life.”
She was found in a newly built city (at the time), and archaeologists don’t know much about her name, age, occupation or social status. What they do know, however, is that she is one of hundreds of people, including many others whose hairstyles are still intact, who were buried in a cemetery near the ancient city now called Amarna.
Amarna is located on the east bank of the Nile River in the modern Egyptian province of Minya, some 58 km (36 mi) south of the city of al-Minya, 312 km (194 mi) south of the Egyptian capital Cairo and 402 km (250 mi) north of Luxor. It was build by the Pharaoh Akhenaten of the late Eighteenth Dynasty (c. 1353 BC), and abandoned shortly afterwards.
Akhenaten was a strange pharaoh who tried to shift Egypt from a polytheistic religion to a monotheistic one, worshiping the solar disk. He ordered that Amarna was built in the desert, in a harsh area with little access to water. It was a time of change for the entire kingdom, and, apparently, fashion was also changing.
Artistic depiction of Amarna. Via Amarna 3D.
Bos and her team found several other women with extensions in their hair, something previously unreported in Egyptian (or any other) culture. She reports a great variety in hairstyles in the city; they range “from very curly black hair, to middle brown straight,” she noted in the journal article, something “that might reflect a degree of ethnic variation.”
It’s quite possible that Amarna was very different from the rest of Egypt. People there seemed to be very fond of braids, and women had rings or coils around their ears, she reports.
“Braids were often not more than 20 cm [7.9 inches] long, leaving the hair at shoulder length approximately,” Bos added. “The longest hair that was found consisted of multilayered extensions to a length of approximately 30 cm [11.8 inches].”
They even found a woman who was dyeing her hair – using an orange color (likely from henna plants) to cover her graying hair.
“We are still not completely sure if and what kind of hair coloring was used on this hair, it only seems that way macroscopically,” said Bos in the email. “At present we are analyzing the hairs in order to find out whether or not some kind of coloring was used. On other sites dyed hair was found from ancient Egypt.”