Tag Archives: natural selection

Not so picky and coy after all: Female animals also have mating contests. They’re just more subtle than males

Sage-grouse on lek site in Central Oregon. Credit: NRCS Oregon, Flickr.

Men chase and women choose. This old-fashioned perspective on dating is also surprisingly prevalent among scientists studying mating dynamics shaped by sexual selection, wherein male animals are seen as more expendable and have to compete for the attention of picky females. But a new study shines light on the often-overlooked female competition for access to quality male mates, showing that sexual selection in females is actually the norm rather than the exception.

Victorian-era sex stereotypes

Charles Darwin claimed that all living species were derived from common ancestors, proposing natural selection as the driving mechanism in his pivotal book On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life. Natural selection says that organisms better adapted to their environment would benefit from higher rates of survival than those less equipped to do so, and would thus be more likely to pass on copies of their genes.

Darwin noted, however, that some elaborate traits had no apparent adaptive purpose and clearly did not aid survival (and in some cases jeopardized it by attracting predators) but rather served a sexual purpose. The male peacock with its extravagant plumage is an often-cited example of this effect. These traits could evolve if they are sexually selected, hence the name sexual selection, which Darwin explored at length in his follow-up book, The Descent of Man.

Sexual selection operates through two mechanisms: intrasexual selection, which refers to competition between members of the same sex (usually males) for access to mates, and intersexual selection, where members of one sex (usually females) choose members of the opposite sex. 

In a new study, a team of researchers led by Salomé Fromonteil of CNRS and the University of Rennes in France argues that the male-centered perspective on sexual selection is greatly exaggerated and has contributed to “a pervasive bias in research agendas of behavioural ecologists and evolutionary biologists over the last decades.

“Despite an increased awareness that females also compete for mating partners, we still tend to consider sexual selection in females a rare peculiarity,” the researchers wrote in a new study that appeared in the preprint server biorxiv.org.

In the 19th-century, Darwin wrote in his original conception of sexual selection that “with almost all animals, in which the sexes are separate, there is a constantly recurrent struggle between the males for the possession of the females” and that “the female […], with the rarest exception, is less eager than the male […,] she is coy and may often be seen endeavouring for a long time to escape from the male.”

This Victorian-era assertion has proven remarkably resilient, largely because there is some truth to it. In 2016, Tim Janicke, an evolutionary biologist at the University of Montpellier in France and co-author of the new study, measured the strength of sexual selection acting upon a variety of animal species and found that males experience a higher degree of sexual selection than females do.

However, the male side of sexual selection is greatly inflated compared to the female side, the researchers argue. For instance, studies exploring aspects of sexual selection on males outnumber those examining female competition for mates and male choice by a factor of ten to one, despite the fact that there are numerous instances of female intrasexual selection in the animal kingdom.

When females compete for males’ attention

Seahorses mating, taken at Seahorse World in Beauty Point, Tasmania. Credit: Flickr, John Dalton.

The clearest examples can be found in so-called sex-role reversed species in which the females actively compete for males and are the more ornamented sex. These include pipefishes and seahorses, in which fertilization takes place inside the brood pouch of the male until the young are ready to hatch, and this male will provide all parental care. In such species, males are a limited resource for which females have to compete, which leads to selection for ornaments favored by males in both pre- and post-copulatory mate choice.

However, nature doesn’t have to be flipped on its head in order to see sexual selection operating in females. Even in species with conventional sex roles where male ornamentation and extravagant courtship behaviors are selected for, you can still see female competition for high-quality males. For instance, female wattled jacanas (Jacana jacana) are known to aggressively fight for control over territory in order to monopolize multiple mates. Meanwhile, dung beetle females have evolved small horns that they sometimes use to battle other females in contests over access to mates. In Black grouse (Tetrao tetrix), both males and females compete for mates in elaborate courtship displayed arenas called leks.

“Consequently, sexual selection in females might actually be an omnipresent phenomenon in animals but operating less intensely and more subtly compared to males, which can make it more difficult to detect,” the researchers wrote.

In their new investigation, Janicke and Fromonteil investigate the published literature reporting evidence of sexual selection in females from 72 species. Particularly, the researchers measured and compared the Bateman gradient, a measure of the fitness benefit of mating, named after 20th-century British geneticist Angus John Bateman.

Bateman’s work showed that males produce sperm at a low energy cost, whereas females have a relatively much higher investment in far fewer eggs. This energy imbalance in gamete investment, Bateman argued, drives competing strategies in males and females. Males are thus incentivized to spread their sperm to as many mates as possible and to compete with other males for access to mating partners, while females are incentivized to be more choosy.

Sex is costly for females but the worst outcome is no sex at all

The Bateman gradient is a measure of the benefit of having multiple mating partners. The steeper the curve of the Bateman gradient, the greater the fitness benefit a male or female gains from mating more.

Although these gradients varied wildly among the species included in the meta-analysis, the researchers found that females from species that had access to many partners had higher Bateman gradient values than females of species that tended to mostly mate with one male at a time.

In effect, this means that, just like males, females also gain a fitness boost from access to multiple males, which naturally opens the door for sexual selection. In fact, the study’s authors claim that sexual selection in females is the norm rather than the exception across the animal tree of life.

“Specifically, our results document that females – just as widely assumed for males – typically benefit from having more than one mating partner. As a consequence, selection is also expected to favour the evolution of female traits that promote the acquisition of mating partners. However, given the previously documented higher benefit of mating in males, sexual selection on females may often operate more hiddenly leading to the evolution of less conspicuous ornaments and armaments compared to males,” they wrote.

While the relative difference in gamete cost between the sexes likely drives important behavioral changes in their mating strategies, the researchers argue that reproductive success may sometimes be maximized when mating with multiple mates or, at the very least, having additional mating episodes.

“Collectively, our study contributes to a more nuanced view on sexual selection and sex differences in general. Darwinian sex roles may predominate the animal tree of life in the sense that sexual selection is typically stronger on males compared to females but our meta-analysis questions the view that females are typically coy and passive. Sexual selection on females should not be considered a rare phenomenon but instead be acknowledged as widespread across animals,” the researchers concluded.

Why mice have the potential to become as venomous as a viper

Credit: Pixabay.

Researchers have investigated the origins of one of the most highly specialized straits in the animal kingdom: oral venom. Unexpectedly, the researchers found that the basic genetic machinery is present in both mammals and reptiles. Specifically, there’s a molecular link between a venomous snake’s venom glands and a mammal’s salivary glands. In theory, if there’s pressure from natural selection, mice could potentially become venomous as well.

“This represents an ancient molecular framework that was likely already established in the ancestors of snakes and mammals. Mammals took a less complicated route and developed simple salivary glands while snakes diversified this system extensively to form the oral venom system. This allowed us to propose a unified model of venom evolution, namely that venoms across lizards and snakes evolved by taking advantage of existing genes in the salivary glands of their ancestors,” Agneesh Barua, a Ph.D. student at the Okinawa Institute of Science and Technology Graduate University (OIST) and lead author of the new study, told ZME Science.

Venom can be defined as a mixture of toxic molecules (“toxins”, which are mostly proteins) that one organism delivers to another (e.g. by a bite or a sting) for the purpose of defending itself, securing a meal, or deterring a competitor. Many different types of creatures — jellyfish, spiders, scorpions, snakes, and even some mammals — seem to have independently evolved venom. This had some scientists wondering whether venom actually evolved from non-venomous but related biological components inherited from a common ancestor. This couldn’t be proved — until now.

Researchers at the Okinawa Institute of Science and Technology Graduate University (OIST) in Japan and the Australian National University carefully assessed thousands of genes related to venom. Previously, scientists had focused on genes that express the toxic proteins found in venom. But Barua and colleagues took it a step further and cast a wider net so they could identify genes that were likely present before the venom system evolved.

To this aim, they used venom glands harvested from the Taiwan habu snake (Protobothrops mucrosquamatus), a pit viper that’s indigenous to Okinawa.

“We have been trying to understand how non-venomous animals evolved venom for a long time. But, this was difficult to do because venoms evolve rapidly and the ancestral state gets difficult to reconstruct with great accuracy. We worked around that by focusing not on the toxins themselves, but on the machinery that makes them, which turned out to be highly conserved,” the researcher said.

More than 3,000 “cooperating” genes were identified that interact in some way or form with venom genes. Some protected the host cells from stress caused by producing lots of toxic proteins, while others regulated protein modification and folding. This is actually extremely important because misfolded proteins can accumulate and damage cells.

“This makes perfect sense because venoms are a cocktail of toxin proteins. It is vital that the protein structure of these toxins is maintained, otherwise, the venom won’t work, and the animal would not be able to catch its prey,” Barua said.

The surprising part was when the researchers looked at the genomes of other animals, including those you’d never think to connect with a venomous creature, such as dogs, chimpanzees, or humans, and found that they contained their own versions of these genes. When they realized that venom genes were actually co-expressed together and with a relatively small number of other genes, this was a “striking moment” for the researchers.

“This suggests that there is a common molecular framework between venom glands in snakes and salivary tissue in non-venomous mammals. This represents an ancient molecular framework that was likely already established in the ancestors of snakes and mammals. Mammals took a less complicated route and developed simple salivary glands while snakes diversified this system extensively to form the oral venom system. This allowed us to propose a unified model of venom evolution, namely that venoms across lizards and snakes evolved by taking advantage of existing genes in the salivary glands of their ancestors,” Barua added.

The study suggests that salivary gland tissues within mammals were expressed by genes that had a similar pattern of activity to that seen in venomous snakes, so genes for salivary glands and venom glands must share an ancient functional core. After the two lineages split hundreds of millions of years ago, the venomous species evolved biological systems that produced toxins, the authors note.

Bearing all of this in mind, it’s not all that surprising that over a dozen species of mammals are actually venomous. These include Eulipotyphla (solenodons and some shrews), Monotremata (platypus), Chiroptera (vampire bats), and Primates (slow and pygmy slow lorises).

Theoretically, this means that virtually any species of mammal could potentially become venomous with enough prodding from natural selection.

“Humans will never develop venom. But there is a distinct possibility in other mammals. For example, suppose there is a genetic mutation in a few individuals of some species of wild mice that allows them to catch more insects. These individuals will be able to procure more food and thus have ‘higher fitness’. This could lead them to out-compete their peers in terms of mating (or just general well-being) and thereby produce more offsprings that will carry the beneficial mutation. Now imagine this happening for several generations. There will come a time when populations of these newly formed venomous mice could drive the non-venomous ones extinct, thereby firmly establishing the venom character in the gene pool,” Barua wrote in an e-mail.

“We would like to try evolving venomous mice in the laboratory. It would be a practical test of the mechanisms we hypothesise in the paper, and potentially provide clues about why venom doesn’t evolve more often.”

In the future, the team of researchers plans on further exploring the genetic regulatory network that underlies venom gland evolution.

“One question is — how does venom evolution modify this network? We’re planning a couple of different studies on this front. One is to look across species that have evolved venom, including other reptiles and mammals. Are there commonalities in these two lineages?”

“One of the main scepticisms regarding the idea of evolution is that of ‘intelligent design.’ Proponents of this idea validate it by citing examples where scientists have not been able to completely decipher the origin of highly specialised traits. Scientists have quite a good idea of how traits originate, but direct mechanistic explanations are rare owing to the incredible genetic complexity of traits. We provide a mechanistic explanation of one of the most specialised traits in nature, oral venoms. Our study, therefore, provides a firm argument for evolution and can provide people will the proof they need to denounce pseudoscientific claims like intelligent design,” Barua said.

The findings appeared in the Proceedings of the National Academy of Sciences.

Evolution: What is it? How does it work?

This is an odd start, but before we get into complicated things I want to talk about something near and dear to my heart—corn. Once upon a time, the corn we know and love (at least I do), used to be something called teosinte, a small green plant that doesn’t look anywhere near as appetizing. It is hard to believe, I know, but something very interesting happened. In the area that is now Mexico, this plant was identified as having potential as a food crop, so farmers began intentionally growing it. Being good farmers, they thought that maybe if they kept the seeds of the biggest ones and kept planting those they would get more food out of it. As it turns out, they were right. After ten thousand years of only planting the ones that produced the biggest kernels, we ended up with maize as we know it today. It’s bizarre but entirely true and it happened through a process we call artificial selection.

In nature similar, very strange changes can happen to species over time given enough pressure by the environment around them. Evolutionary biology is essentially the study of how organisms have changed over time to develop into new species. The topic is a bit contentious, as we all know, but there are also many common misconceptions about exactly how this process works. Thinking about it as a whole is difficult, with many points where it is easy to get hung up and confused. So, instead of looking at the big strange picture, we should start with a closer look at the little parts that make up the concept. As we move into this article, remember that, ultimately, every species needs to survive and reproduce because that’s how species continue to exist. With that said, let us take a look!

Credit: Pixabay.

Getting Fit

Let us consider two individuals, Tom and Jack. Tom is long-limbed, athletic, lightweight, and doesn’t have much body hair. Jack is shorter, has a fair amount of hair, and a larger, higher-fat build. If you put both of these men in a forest, it is likely that Tom will have a bit of an advantage with traversing, climbing, et cetera. However, take the same pair and put them in a windy tundra and Jack will likely do a lot better in the harsh weather.

Every environment poses its own unique challenges. If you live in an area that has a lot of water, you will do a lot better if you can swim. If you live in an area that has a lot of plants and cover, predators are less likely to see you if you’re small and green. These factors contribute to something we call fitness which is a measure of how well you are built to survive and how likely you are to reproduce. In some ways, it’s a bit like physical fitness in humans. And, similarly, this fitness affects more than just your looks.

Genetics plays a huge role in this, and your genes (genotype) are expressed through your outward characteristics, called your phenotype. Small brown lizards living in a forest are displaying (‘expressing’) genes that give them the small and brown phenotype, and maybe even more than tell them to like staying on surfaces that match their color. Which brings us to the next main idea, a process called natural selection.

Selection Bias

Natural selection looks at the differences in the likelihood of survival and reproduction based on a species’ phenotype. Ultimately, in nature, creatures that have genes that result in fit phenotypes will survive and reproduce. This concept is where the term “survival of the fittest” comes from. The survivors live to have offspring and so genes in that population will, therefore, start leaning towards that fitter survivor genotype. Let us use an example.

Imagine that in a grassland there is a population of mostly large, green grasshoppers. They are doing well here because nature provides a lot of cover. This season, though, there isn’t much rain and the grassland starts turning brown and sparse. This means that the larger, brighter grasshoppers become much easier to see by predators and many of them get eaten. So, the next generation of grasshoppers ends up being mostly smaller and perhaps a bit less green, because the ones that best survived the change in the grasslands were the ones that were harder to see.

This is natural selection. Those built to survive in an environment will live long enough to have offspring, changing the gene variety in the next generation. The same process happens with plants, fungi, and microorganisms. An important thing to note here, though, is that this is only possible because a healthy population has a wide range of genes to choose from. Not all organisms of a species will be the same size or the same color or have the same features.

Darwin's Finches

Charles Darwin is considered the father of modern evolutionary biology. He developed his theory of natural selection by observing the variations among the species of the Galapagos Islands. He was best known for his study of birds, which all occupied different niches on these far islands but bore obvious resemblances to mainland species. Image credits: John Gould.

Over a long period of time and given a lot of pressure, a population of organisms can change in significant ways. The reason we are now having an antibiotic crisis is that, after many years of exposing bacteria to chemicals designed to kill them, the ones that had the gene quirks allowing them to survive are the ones that were able to multiply. So now we have a large number of antibiotic-resistant bacteria to contend with which have whole sections of DNA that exist only to counteract these drugs—but that, of course, raises a question. If they didn’t have these genes before, why do they have them now?

Mutant Power

Credit: Pixabay.

Credit: Pixabay.

Mutation is a major factor influencing the process of evolution. Every so often, when cells are dividing, the mechanisms that copy bits of genetic data make a mistake. While it can often result in problems, it sometimes creates just what an organism needs to survive. One reason why HIV has been so hard to cure is that its reproduction process is unstable and prone to genetic errors. What this means is that the medication will work on most viral particles, but not all of them. The virus is, therefore, constantly evolving and the ‘error’, mutant forms that help it survive to persist due to natural selection.

Some mutations are overtly harmful, like mutations in hemoglobin genes that cause sickle cell disease, where red blood cells curve into a “sickle” shape. The mutation makes the cells less efficient oxygen carriers and more fragile, and sometimes they cause painful blockages and organ damage. However, these mutations continue to persist because if a person is only a carrier, having received the variant gene from only one parent, it has a protective effect against malaria—a common disease in the parts of Africa where sickle cell is most prevalent. The fragility of the cell due to the hemoglobin structure means the cell will often rupture before the parasite can reproduce. But, since the remainder of their hemoglobin is normal, they don’t experience most of the severe effects seen in persons with the full form of the disease. The carrier phenotype is, therefore, fit. Natural selection is a strange process indeed.

So we have looked at mutation, natural selection, and fitness. We have looked at bacteria and viruses and how these factors have made them survive and evolve on a smaller faster scale. Now, how does that translate to bigger more complex things?

Making Sense of it All

Imagine that there is a ground-dwelling species of mammal that lives in a forest. Many of them are competing for the same food sources. A few of them, have started climbing in the hopes of finding another food source. A mutation comes which makes one offspring’s claws curve a bit more, causing that individual to be better at climbing. It survives to reproduce. A few generations down the line, all its descendants may have these curved claws. Somewhere along the line, a descendant is born with unusually long limbs which makes it better at both climbing and jumping, this individual’s offspring may well, do better than others—and so on. These minor changes can add up over time, just like the biggest teosinte kernels being intentionally planted. In nature, however, it takes far longer than a neat ten thousand years to produce something as different as maize.

Let this mammal group adapt for many thousands of years with natural selection favoring climbing habits and hunting in trees. At the end of that time if you were to take one of these climbing adapted creatures and put them alongside the ground dwellers they would look very different. They may have a different body form, make different sounds, have eyes that are adapted to seeing at a distance, and so on. And, because of the amount of mutation and genetic changes that brought them to this point, any offspring born of a mix of these two creatures would be sterile like a liger or mule. Just like that, you now have two different species. This also speaks to a common misconception, the idea that if one organism advanced from another, the first one should be gone. That simply isn’t how the process works.

In nature, creatures will exist side by side as one group remains the same and others experience changes due to environmental pressure. It is strange, and hard to fully appreciate, but we have a bit of evidence that can follow the trail. Think even of the liger I just mentioned, the mere fact that a lion and tiger—two distinct species from two different regions—can produce offspring means that their genotypes must be similar enough to make an embryo viable. We interpret this to mean that these big cats must have some ancestry in common.

What Do We Know?

Though it happens over a very long period of time in creatures that take longer to reproduce than bacteria or viruses, there are a few ways we can observe that evolution is an acting process. If an organism has advanced from one form to another, it stands to reason that there had to be some forms in between. Well, though we don’t always have all the bits of the puzzle, the fossils we find often help us fill these gaps. For example, between dinosaurs and birds we have found species of feathered, winged dinosaurs like Archaeopteryx.

There are also several odd cases in nature of organisms growing parts they have no need for. Some snake species and legless lizards retain a pelvic girdle with no real function, dolphin embryos in development still start to grow hind limb buds that retract after a time, and many cave-dwelling or burrowing species retain non-functioning eyes. The fact that the genetic machinery required to make these structures happen exists, presents as evidence that these genes had a purpose at some point in the organism’s history.

There are other factors to consider as well. Genetic evidence frequently shows fairly small differences between one species and another of a similar type that cannot reproduce with each other. In fact, genetic evidence shows that a large variety of organisms have a surprising number of genes in common—whales, humans, bats, and cats all have the same bones making up their forelimbs. But, this gets into very complex discussion and murky waters. This article really just serves to give a background of a concept. Take the information here, interpret and think about it as you will and, of course, there are many other great sources of information on the topic out there. Whether evolution on a larger scale makes sense to you or not, hopefully we can at least agree that these smaller processes of change are things we can observe. By now, I hope, the idea of what evolution is and how it works is at least a little bit clearer.

Debunking some misconceptions about evolution

Early human skull.

Image credits Paul Hudson / Flickr.

Evolution, by and large, has had center stage in shaping life as we know it. Everything that roots or runs, burrows or swims, grazes, pecks, or stalks has been steered by its hand. The idea has also sparked one of the most heated debates humans have ever thrown their collective lot into — that of our origin.

This debate revolves around two opposing ideas: intelligent design (or ‘creationism’) and evolutionism. Often messy, this debate has muddied the scientific waters from which the latter theory spawned. Presenting the debate as a choice between two entities tends to somewhat put the two on the same level in our subconscious. Pitting it against quite literally the concept of divinity makes it easy for us to impart almost supernatural, godlike traits to the process of evolution — to think it almost a living creature, that shapes life according to its own wants and whims. After all, something which replaces the work of gods must be a pretty powerful and impressive force in and of itself, right?

And so, we come around to what we’re going to sink our teeth into today: some of the misconceptions that I have seen surrounding the idea of evolution.

That evolution created life, and the theory of evolution equates to a theory about the origin of life.

Certain aspects of the theory of evolution do relate to the origins of life — such as what types of organisms came first, what they ate, where they lived, how they shaped all life to come. Overall, however, the theory of evolution aims to understand how life behaved after it appeared, how it changed to suit its environment. This intrinsic property makes evolution and abiogenesis (the natural process by which life arises from non-living matter) very separate things. No life, no evolution.

Equating the two is like saying all chemistry is actually physics because it deals with atoms, which are physical particles. If you look at a limited-enough part of these fields, that statement can technically stand true. The big picture, however, is that we have different names for the fields because they deal with different bits of the natural world: chemistry with the composition, structure, properties, behavior, and the changes that compounds of atoms and molecules undergo through reactions with one another; physics looks at matter, its motion and behavior through space, as well as energy and forces.

To stretch this analogy even further, evolution resembles chemistry in that it studies how organisms change over time through reactions with their environment and other organisms. Abiogenesis, like physics, looks at what processes allowed those organisms to form in the first place.

That it aims to create a ‘perfect organism’, at which point the process of evolution will be ‘complete’.

This one is a bit more convoluted, so bear with me.

Puzzle piece.

Image via Pixabay.

First, it’s important to note that evolution doesn’t have a goal; it is the journey, not the destination.

New generations partly inherit characteristics from their parents, partly take on new ones through mutations (a permanent change in an organism’s genotype). Mutations can be either good for the organism (such as making it more resistant to a certain pathogen), bad (making it more vulnerable to a certain pathogen), they can have mixed effects, or no effects at all! It’s a lottery.

[accordion style=”info”][accordion_item title=”Genetics vs. appearance”]An organism’s genotype is the part of its genetic makeup that determines one of its outer characteristics. The sum of the latter makes up the phenotype. As a rule of thumb, think of the genotype as an organism’s genetic blueprint, and of the phenotype as the end product, with all the scratches, dents, and new coats of paint it got over its lifetime.[/accordion_item][/accordion]

Genes are (or, rather, used to be) built with four building blocks called nucleotides: adenine, thymine, guanine, and cytosine (or ‘A’, ‘T’, ‘G’, and ‘C’). Note that in RNA, thymine is replaced by uracil (or ‘U’). What makes each nucleotide distinct are bits called nitrogenous bases, which form the rungs in the DNA ladder. The side rails are made of sugar molecules tied to pieces called phosphate bases, which stack on top of another. A only ties with T and G only with C, but, because they use the same sugar molecules to connect to the rest of the DNA strand, these pairs can switch places — and you get a mutation. Alternatively, pairs can be unwittingly deleted or inserted into the strand. This, again, causes a mutation.

Over successive generations, enough mutations build up in the genotype to subtly change a species’s phenotype. Over longer spans of time, this process will generate entirely new species (significant changes in phenotype) from pre-existing ones. That’s why evolution can’t be ‘complete’: it is the change.

Secondly, an organism’s ‘perfection’ can only be gauged in relationship to something: a perfect ocean mammal will be, literally and figuratively, completely out of its depth on a mountain peak.

Which brings us to the next point on our list.

That evolution doesn’t have a direction — it’s random!

Funny animal.

Image via Pixabay.

The word ‘evolution’ refers to gradual development. In the context of our discussion today, the change in the genetic heritage of organisms over time. We’ve seen that it’s an ongoing process that can bestow younglings with both great advantages or crippling shortcomings — however, in its eyes, all mutations are equal.

Evolution through natural selection, however — the theory Darwin developed — is what people generally refer to and shorthand as ‘evolution‘. The gradual development we’ve just talked about is random and yields random mutations, but the end product of evolution (through natural selection) is not random.

Natural selection is where mutations go to be judged. It’s the quality control department of evolution; the sieve that separates the fittest wheat from the illest-adapted of chaff.

It sounds like a fancy concept, but it’s actually really simple. ‘Natural selection’ basically encapsulates the idea that environments put certain pressures on organisms: to find food, to stay warm, to not get eaten, to find a mate, etc. How well an organism meets these requirements determines a lot of factors, such as how long it will live, and how well it will be able to defend itself. In the end, however, all these factors are only proxies for the one overriding goal all life shares: to continue its own image by passing on its genes.

[accordion style=”info”][accordion_item title=”Why do we mutate, then?”]Mutations generally result from either errors while a cell tries to copy produce more DNA and split, or from chemical, biological, or physical damage to the DNA molecule. Cells have safety systems in place to spot and fix mutations, but some still slip through.[/accordion_item][/accordion]

Nature is pretty much a dog-eat-dog rat race (double cliches are the best cliches). Even slight disadvantages from unfortunate mutations will make an organism more likely to die — which dramatically limits its baby-making potential. At the same time, even a seemingly inconsequential boon from one’s genetics could provide an edge in mate-ability. Thus, species weed themselves of poor mutations over time, while retaining and even amplifying positive ones. Through the process, they change. The changes are random but, by pitting them against the environment, the overall direction species evolve in isn’t random — it’s guided.

In other words, evolution causes each organism in a species to be a tentative first step towards a new genetic lineage, complete with strengths and weaknesses. But it is the gene-borne ability of each individual to adapt to their natural environment that selects which get to make babies and spread their DNA.

Which should make the next misconception pretty confusing to read at first:

That evolution always favors the fittest.

Fittest cows.

For example, these impressively fast cows.
Image credits Alan Levine / Flickr.

Reading between the lines of the point we’ve discussed above, specifically in the “how well an organism meets these requirements” part, there’s a hidden kernel of wisdom; one that, I find, does wonders during a stressful day. Even in the eyes of evolution, you don’t have to be ‘perfect’ — ‘good enough’ is, really, good enough.

Natural selection is a sieve rather than a competition because it allows individuals to have whatever traits their genes give them, as long as they’re able to survive (and mate). The process doesn’t single out the best in the species to breed that over and over. It just slowly murders those who can’t keep up, along with their genes. Everyone else can keep on keeping on.

What natural selection rewards is adaptability, not ability.

For example, take yours truly. I like to fancy myself a well-adapted guy, mostly due to my solid entrenchment at the top of the food chain. But my wisdom teeth, thanks to a genotype that made my jaw too small for them, are solid agony. There is no shadow of a doubt in my mind that, bereft of modern medicine, I would have gladly poked a bear with a sharp stick, trying to look tasty while pleading for it to maul me, just so I wouldn’t have to endure the pain.

I am definitely not the fittest. And, in the wild, I very likely wouldn’t have been fit enough either. But in my environment, I’m just good enough.

Another point I’d like to make here, again, is that the very idea of being the ‘fittest’ implies a standard of measurement. A standard which may or may not hold true between species — for example, a plant’s standard could be how well it photosynthesizes, a bear would judge its fitness through physical strength, while you or I would much prefer cognitive ability. Two species can be just as fit to thrive in the same conditions even if they have very different characteristics.

Nature always finds new solutions to old problems, and the fitness of an organism can only be gauged in relation to its environment. The kakapo, for example (Strigops habroptila), was superbly adapted to its environment in New Zealand before humans arrived. This fluffy, flightless parrot had no natural predators and ample resources of food — so it evolved into this cute, fat bird that has almost no concept of fear and tons of libido. Tons of libido; here’s Stephen Fry intruding on the privacy of one happy kakapo and one quite (un?)lucky photographer:

Today, however, the birds have fallen on hard times. After humans got there, first Polynesians and later Europeans, it was hunted intensely since it was plump, tasty, and didn’t run away. Humans have also brought invasive predators that decimated the species: as of February 2018, the Kakapo Recovery Programme’s page reports the total known adult population amounted to 151 living individuals.

The kakapo has gone from one of the most successful species in its environment to being listed as critically endangered on the IUCN’s Red List — all because some new organisms showed up and changed the ecosystem.

That evolution always means ‘better’ versions of organisms.

Level 2.

Image credits Alan Levine / Flickr.

My main gripe with this idea actually has to do with what people generally envision as progress. In an age when new phones have better specs than the last, new cars are faster than the old ones, and new rockets are cheaper than the old ones, we tend to assume that ‘progress’ equates to a linear improvement. When talking evolution, then, the impression is that progress means bigger muscles, sharper beaks, thicker furs — a certain number of characteristics that simply get an upgrade.

But let me ask you this: say you have your standard Mk.I polar bear, and one lineage then evolves into the Mk.II. It’s better across the board. It’s much faster and stronger because it has bigger muscles. It can bear much lower temperatures because it has a thicker coat of fur and more fat under its skin. It’s also bigger, and nothing in its ecosystem can dare stand up to it. Let’s even go wild and give it a sonar, just like the ones dolphins have.

The Mk.II nearly wipes the Mk.I clean off the face of the Earth because it’s so much better at being a polar bear than its predecessors. But as they compete, human-induced climate change starts heating up the poles. Mean temperatures increase, ice cover begins to shrink, and food becomes scarcer as polar bears need ice to hunt seals.

In this scenario, being bigger, fatter, and having more muscle could actually pose a disadvantage, as it means the Mk.II needs more food to survive. Being heavier also means that it’s less likely the Mk.IIs will find ice chunks thick enough to sustain their bulk. The thicker mane means they have to spend more energy trying to regulate body heat, since it’s too warm for thick furs now. Size, while still an advantage in itself, also quickly becomes a liability, as other animals in their ecosystems are increasingly looking at them as potential meals — since they’re so meaty.

Evolution (through natural selection) would quickly start to favor the smaller but less food-intensive Mk.I over the newer, assumed-to-be-better species.

It’s an extreme example, but it gets the point across an organism with traits that are beneficial in one situation may be poorly equipped for survival when conditions change. Evolution and natural selection don’t work to churn out ‘better’ life. They work to make better-adapted life.

It’s a subtle nuance, but a significant one.

Bonus round — That evolution is always slow and humans aren’t evolving any longer.

Evolution meme.

“Astronomy Evolution 2” by Giuseppe Donatiello.

Generally, evolution and natural selection take a lot of time. But there is evidence of (relatively) rapid evolution in the fossil record; for example, some species of foraminiferans, which are a type of single-celled organism. It’s not rapid as from one generation to the next — the paper I’ve linked describes how two genera, Morozovella and Acarinina, differentiated into two new morphotypes, M. africana, and A. sibaiyaensis, as well as a completely new species, M. allisonensis, in under ten thousand years.

[accordion style=”info”][accordion_item title=”Morphotypes?”]Morphotypes are a group of individuals that are part of a species but different enough to stand out and be distinguishable from the rest. [/accordion_item][/accordion]

Now, ensconced comfortably in our concrete ecosystems, it’s easy to think we’re out of the grasp of evolution and natural selections. But boy, oh boy is that wrong.

We’re not yet at the point where we can control our mutations, so evolution still reigns supreme over our biology. Our technology, medicine, all our know-how do, however, influence the effect of natural selection on our species — but that’s not the same as eliminating it altogether.

For example, we can now treat diabetes with insulin, meaning that (at least in developed countries) the disease isn’t as powerful a selection criteria as it used to be — in blunter terms, the mutations that contribute to the condition aren’t as likely to get you killed. The reverse is that we’re also no longer weeding out the faulty gene versions, as we used to.

At the same time, we’ve gained new selective pressures — we live in denser groups, meaning we’re at higher risk of epidemics. Throughout time, these genes that confer resistance to disease become increasingly important and increasingly selected for in our collective gene pool. Modern medicine largely insulates us from epidemics today, but if one hits and we don’t have a cure, those whose genes can provide an edge will be around to repopulate, and the rest likely will not. Thus, those genes will become even more prevalent.


Phew, that was long — you guys have probably already started to select for longer-than-average attention spans!

I do hope you found it interesting and that it helped patch up your understanding of the subject. These are just the most common misconceptions I’ve run into when discussing the topic, but that doesn’t mean these are the only ones floating around out there. If you’ve got something that you feel could join them on the list, leave us a comment down below.

The researchers imagine a complex alien called the 'Octomite' which is comprised of a hierarchy of entities, where each lower level collection of entities has aligned evolutionary interests such that conflict is effectively eliminated. Credit: University of Oxford.

Aliens could be more like us than we think, say Oxford scientists

Humans might have more in common with our yet inconspicuous galactic neighbors than we thought. According to scientists at the University of Oxford, natural selection and evolutionary theory seem to favor organisms that behave similarly to those found on Earth.

The researchers imagine a complex alien called the 'Octomite' which is comprised of a hierarchy of entities, where each lower level collection of entities has aligned evolutionary interests such that conflict is effectively eliminated. Credit: University of Oxford.

The researchers imagine a complex alien called the ‘Octomite’ which is comprised of a hierarchy of entities, where each lower level collection of entities has aligned evolutionary interests such that conflict is effectively eliminated. Credit: University of Oxford.

Astrobiologists — scientists concerned with the study of life outside Earth — have their work cut out for them in this day and age. Since no alien organisms have been found yet, their field of study is riddled in uncertainties and speculations. Given the vastness of the cosmos and what we know about potentially habitable planets, the odds of Earth being the only planet in the universe capable of hosting life look very slim. It seems extremely unlikely that life on Earth is unique.

At the same time, making predictions about alien life is challenging, especially when you have one example to work with: life on Earth. Previously, scientists have predicted what alien life might look like by extrapolating what we know about organisms on Earth, as well as the chemistry, geology, and physics on our planet.

But these “past approaches in the field of astrobiology have been largely mechanistic,” says Sam Levin, a scientist at Oxford’s Department of Zoology. He and colleagues have gone a different route that’s more principle driven and less dependent on Earth-centered assumptions.

“In our paper, we offer an alternative approach, which is to use evolutionary theory to make predictions that are independent of Earth’s details. This is a useful approach, because theoretical predictions will apply to aliens that are silicon based, do not have DNA, and breathe nitrogen, for example,” Levin said in a press release. 

The researchers did assume at least one process that’s fundamental to Earthlings governs alien life as well: natural selection. Starting from natural selection as a framework, the researchers built a model of extraterrestrial evolution.

alien evolution

These illustrations represent different levels of adaptive complexity Different levels of adaptive complexity triggered by ‘major transitions’. (a) A simple replicating molecule, with no apparent design. This may or may not undergo natural selection. (b) An incredibly simple, cell-like entity. Even something this simple has sufficient contrivance of parts that it must undergo natural selection. (c) An alien with many intricate parts working together is likely to have undergone major transitions. Credit: University of Oxford

More of the same

Though the origin of life on Earth is still a matter of debate, we know that the very first creatures were simple, single-celled organisms. Over the course of countless generations, some of these single-celled organisms merged, learned to cooperate, and formed multi-cellular organisms. Complexity jumped in steps caused by a handful of events known as ‘major transitions’. The transitions from prokaryotes to eukaryotes or from asexual clones to sexual populations are some prime example. Both evolutionary theory and empirical data suggest that extreme conditions say sudden climate change, are required to drive a major transition.

With this framework in mind, the Oxford scientists made some predictions about what alien life might look like, complete with some illustrations to boot.

Of course, no one can say if aliens walk on two legs or have four eyes. The Oxford team, however, says that there’s a level of predictability to evolution which would cause aliens to look at least a bit like us, they reported in the International Journal of Astrobiology. In other words, they’d look and function more similarly to humans than differently.

“Like humans, we predict that they are made-up of a hierarchy of entities, which all cooperate to produce an alien. At each level of the organism there will be mechanisms in place to eliminate conflict, maintain cooperation, and keep the organism functioning. We can even offer some examples of what these mechanisms will be,” Levin said.

“There are potentially hundreds of thousands of habitable planets in our galaxy alone. We can’t say whether or not we’re alone on Earth, but we have taken a small step forward in answering, if we’re not alone, what our neighbours are like,” he added.

neolithic life

How agriculture shaped our genes through natural selection

neolithic life

Once with the advent of agriculture, and its spread to Europe from the Near East, human society was transformed forever. Resources became more plentiful, communities could stay in one place and develop, and humans were free to pursue other activities. Agriculture turbo boosted the division of labor, an essential prerequisite to any civilization. Agriculture not only transformed human society, but it also modified our DNA. A first-of-its-kind study compared the DNA of ancient humans who lived between 8,500 and 2,300 years ago. The analysis revealed that humans underwent widespread genetic changes that influence height, immune system, digestion, and skin colour once agriculture was introduced.

The early homo sapiens settlers in Europe were all hunter-gatherers. This was the norm for over 35,000 years, until some 8,500 years ago when a massive migration of farmers started flocking into Europe from the Near East. Then, some 4,500 years, came the third major migration into Europe from the Russian steppes. These migrants were the so-called Yamnaya people, which were master horse herders. The Yamnaya also employed sophisticated technology for the time, like wheeled carriages, and knew how to tender to flocks of livestock like sheep and cattle. Incidentally, ZME Science reported last week how this third tribe may actually be comprised of two genetically distinct lineages, meaning there were four founding tribes of modern Europeans, not three like the current consensus suggests.

To see what kind of changes these major migrations had on our DNA, David Reich, a geneticist at Harvard Medical School, and his colleagues sequenced the genomes of  230 people. The samples were recovered from skeleton remains collected from the entire continent of Europe. These include hunter-gathers, Yamnaya, but also 21 individuals who lived in  Anatolia 8,500 years ago. Anatolia or modern-day Turkey has considered the stepping stone early farmers made before migrating into Europe.

Reich and the team came up with some very interesting results. After humans in Europe started to farm, a certain gene called SLC22A4 proved most useful. This gene encodes a protein that helps absorb more of the amino acid called ergothioneine, found in wheat and other crops. Those who had the genes had more chances to survive and pass on their genes. Previously, researchers posited that humans became able to digest milk once they raised cattle.  LCT, a gene that aids milk digestion, got spread out through natural selection around 4,500 years ago. It could be that raising cattle wasn’t that widespread until the Yamnaya came around the same time.

Another interesting finding concerns skin color. Hunter gathers in Europe had dark skin, the early farmers who came to Europe 8,500 years ago were lighter colored. Later, a new gene variant emerged that lightened European skin even more. Two things might have happened. For one, the Yamnaya were light-skinned, and their skin coding genes might have dominated Europe once they mixed. The Yamnaya stem from the Caucasus, which is why we call white people Caucasians. Then, there’s this hypothesis concerning Vitamin D intake from sunlight. Lighter skin helps capture more Vitamin D, but somehow the hunter-gathers managed to stay dark-skinned. That’s because they got their Vitamin D from meat,  Dr. Reich says. Once agriculture became widespread, natural selection started working in overdrive again and in time the population developed a lighter tone. Maybe both hypotheses are at play.

On height, the researchers found Anatolian farmers were taller than hunter-gathers, and the Yamnaya taller still. Northern Europeans inherited a larger amount of Yamnaya DNA, which might explain why they’re so tall, on average.  For the future, Reich and colleagues plan to analyze even more European DNA to uncover more natural selection effects. “I think in the future we can do this everywhere in the world, not just in Europe,” Dr. Reich told the NY Times.

Eppie Jones of Trinity College Dublin, co-researcher on the study, said: “This paper is taking our journey back in time even further.

“It is looking at our genes and how the interactions and innovations through history have shaped who Europeans are today.”

Scientists create ‘artificial evolution’ for the first time

Scientists have made a significant step towards developing fully artificial life – for the first time, they demonstrated evolution in a simple chemistry set without DNA.

In a way, the researchers showed that the principle of natural selection doesn’t only apply to the biological world. Using a simple a robotic ‘aid’, a team from the University of Glasgow managed to create an evolving chemical system. They used an open source robot based upon a cheap 3D printer to create and monitor droplets of oil. The droplets of oil were placed in water-filled Petri dishes, and each dropled had a slightly different mixture of 4 different chemical compounds.

Photographs of the droplet behaviour as a function of time (from left to right) for all the traits (given in a–i). Image credits: Cronin et al, 2014.

The robot used a simple video camera to monitor, process and analyse the behaviour of 225 differently-composed droplets, identifying a number of distinct characteristics such as vibration or clustering. The team focused on division, movement and vibration as parameters to study evolution. They used the robot to deposit populations of droplets of the same composition, then ranked these populations in order of how closely they fit the criteria of behaviour identified by the researchers. They then created a new generation of droplets, with the best matching (“fittest”) composition carrying on to the second generation. After repeating this process for 20 generations, they found that droplets became more stable, mimicking the natural selection of evolution.

In other words, the robot acted as like a selection mechanism – much like environmental factors act in nature for organisms, and the chemical droplets acted like organisms, “improving” with each generation. Professor Lee Cronin, the University of Glasgow’s Regius Chair of Chemistry, who led the study said:

“This is the first time that an evolvable chemical system has existed outside of biology. Biological evolution has given rise to enormously complex and sophisticated forms of life, and our robot-driven form of evolution could have the potential to do something similar for chemical systems.

Photograph showing the pumps: cleaning and oil phases, the mixing array, the syringe array held in the X–Y stage, the evolutionary arena, the optical imaging system held below the evolution arena, the motors controlling the X–Y carriage and the computer interface. Image credits: Cronin et al, 2014.

“This initial phase of research has shown that the system we’ve designed is capable of facilitating an evolutionary process, so we could in the future create models to perform specific tasks, such as splitting, then seeking out other droplets and fusing with them. We’re also keen to explore in future experiments how the emergence of unexpected features, functions and behaviours might be selected for.

“In recent years, we’ve learned a great deal about the process of biological evolution through computer simulations. However, this research provides the possibility of new ways of looking at the origins of life as well as creating new simple chemical life forms.”

This is not the first time evolution has been demonstrated outside of biological systems. However, it’s the first time it has been done in the physical world. By this I mean that evolution has often been emulated in software.

Journal Reference: Juan Manuel Parrilla Gutierrez, Trevor Hinkley, James Ward Taylor, Kliment Yanev & Leroy Cronin. Evolution of oil droplets in a chemorobotic platform. Nature Communications 5, Article number: 5571 doi:10.1038/ncomms6571

darwin cambridge manuscript

Cambridge University releases over 12,000 images from Darwin’s original notes

Charle’s Darwin’s original notes during which he first scribbled down the ideas which led to evolution have been digitized and published online by Cambridge University. Over 12,000 high-res images have been published online – including the ones with the pages where he actually coins the term ‘natural selection’.

darwin cambridge manuscript

Charles Darwin. Image via Cambrdige Digital Library.

“One may say there is a force like a hundred thousand wedges trying force ‹into› every kind of adapted structure into the gaps ‹of› in the œconomy of Nature, or rather forming gaps by thrusting out weaker ones” – Charles Darwin, 1838, original notes.

The work was part of the Darwin Manuscript Project – a historical and textual edition of Charles Darwin’s scientific manuscripts, designed from its inception as an online project. The database of catalogues contains some 96,000 pages of Darwin scientific manuscripts, including the newly added pages. Professor David Kohn, Director of the Darwin Manuscripts Project, was thrilled of these new additions:

“These documents truly constitute the surviving seedbed of the Origin. In them, Darwin hammered out natural selection and the structure of concepts he used to support natural selection. It was here also that he developed his evolutionary narrative and where he experimented privately with arguments and strategies of presentation that he either rejected or that eventually saw the light of day with the Origin’s publication on November 24, 1859.”

This also marks the end of the first phase of funding for the Cambridge Library, launched to worldwide acclaim in 2011 with the publication of Isaac Newton’s scientific archive. The main goal of the project is to digitize old notes and make them open access – available for everyone. The current release is particularly special as it includes important documents such as the “Transmutation” and “Metaphysical” notebooks of the 1830s and the 1842 “Pencil Sketch” which sees Darwin’s first use of the term “natural selection”.

Charles Darwin’s notes – the first use of the term ‘natural selection’. Image via Cambridge Digital Library.

The library also contains other remarkable manuscripts, including over 500 religious manuscripts South Asia, including Vedic, Hindu, Buddhist and Jainist texts. Hopefully, the funding will continue, and more works will be digitized. Anne Jarvis, Cambridge University Librarian, said:

“With seed funding from the Polonsky Foundation, we launched the Cambridge Digital Library in 2011 with Isaac Newton’s papers, declaring our ambition of becoming a digital library for the world, opening up our collections to anyone, anywhere on the planet with access to the Internet. Now, after millions of visits to the Digital Library website, we bookend our first phase of development with the launch of Charles Darwin’s papers and our Sanskrit collection. These now sit alongside Newton’s scientific works and a wealth of other material, including the Board of Longitude papers and, most recently, our Siegfried Sassoon archive.”

See the manuscripts at the Cambridge Digital Library.

The finch known as Big Bird. Photo: Peter and Rosemary Grant

Biologists witness the birth of a new species before their very eyes

In his magnum opus, ‘On the Origin of Species’, Darwin writes about how evolution and natural selection is omnipresent and working ceaselessly for all living organisms, yet “we see nothing of these slow changes in progress, until the hand of time has marked the lapse of ages.” In other words, evolution works its magic so slowly that to us mortals won’t be able to witness it in action until our nephew’s nephews. Charles Darwin only spent a few months on the Galápagos Islands, however, compared to the past 40 years  British biologists Peter and Rosemary Grant have.

Evolution in action

Peter and Rosemary Grant on Daphne at work. Photo: K.T. Grant

Peter and Rosemary Grant on Daphne at work. Photo: K.T. Grant

If the two sound familiar, you might know them as being featured on the popular science book “The Beak of the Finch“, by Jonathan Weiner. Published in 1994, at a time when 50% of Americans refused to believe in evolution, the book provided an entertaining read on how evolution works. Now, writing for the New York Times, Weiner offers us a precious update of what the married biologist couple have been up to – their discovery is hailed as nothing short of a breakthrough in evolutionary biology.

The finch known as Big Bird. Photo: Peter and Rosemary Grant

The finch known as Big Bird. Photo: Peter and Rosemary Grant

The Grants have visiting the tiny uninhabited island of Daphne Major, the cinder cone of an extinct volcano, each year since 1973. The vigorous duo, now each 77 years of age, would camp in the same spot, near a cave, and exclusively study  the finches in the genus Geospiza – the same birds that offered Darwin key insights that led to the formation of his groundbreaking theory on evolution and natural selection.

They were looking to reconstruct the finches’ evolutionary history, but instead they found something else – the birth of a new species before their very eyes! Weiner writes in his editorial:

“Its own origins date to 1981, when a strange finch landed on the island. He was a hybrid of the medium-beaked ground finch and the cactus finch. He had the sort of proportions that touch our protective feelings: a big head on a stout body. In other words, he was cute. They called him Big Bird.

Hybrids are not unknown among Darwin’s 13 species of finches, but they are rare. Because they evolved so recently, birds of these different species can mate but ordinarily choose not to. (Our own ancestors seem to have felt the same way about Neanderthals.)

Big Bird had a strange song that none of the finch watchers had ever heard. His feathers were a rich, extra-glossy black. He had more tricks in his repertory than his neighbors: He could crack the spiky, troublesome seeds of the Tribulus plant, normally the specialty of the big-beaked ground finch, as well as small seeds favored by the small-beaked ground finch. He could dine on the nectar, pollen and seeds of the cactus, which belongs to the cactus finch.

Big Bird mated with a medium-beak on Daphne. Their offspring sang the new song of Big Bird. And slowly, Big Bird became a patriarch. He lived 13 years, a long time for one of Darwin’s finches. His children, grandchildren and great-grandchildren all sang his song, and they were clannish. They roosted in hearing distance of one another on the slopes of Daphne Major. What’s more, they bred only among their kind, generation after generation.

Big Bird’s lineage has now lasted for 30 years and seven generations.”

The findings top more than 30 years of pain staking observations, providing perhaps some of the best empirical evidence that supports the theory of evolution. Notable figures in the field did not shy away from praising the effort.

“The Grants’ work is possibly the most important research program in evolutionary biology in the last half-century,” Dr. Losos said. “It has reshaped both how we understand evolution and how we study it. Before their work, no one was trying to study evolution in action — now it seems that everyone is.”

The island of Daphne Major. Photo: D. Parer and E. Parer-Cook

The island of Daphne Major. Photo: D. Parer and E. Parer-Cook

While still healthy, sadly the Grants lack their youthful vigor that once helped them return to Daphne Major each year, but their pioneering observations will definitely spark other researchers to follow in their footsteps, either on the same tiny volcanic island or on some of the myriad of tiny ecosystems this planets shelters that are perfectly fit to study evolution at its finest. If you’d like to read more about the Grants’ story, consider reading their latest book authored together – “40 Years of Evolution.”

siberia-woman

How natural selection helped Siberian natives survive harsh cold

Though Siberia stretches across about 10% of the world’s land surface, it’s only occupied by 0.5% of the world’s population, which isn’t too hard to explain why. Recent temperature measurements read on average -25°C for the month of January, but it’s not unheard of to experience temperatures below -40°C. Extreme weather, temperatures and terrain, however, call for extreme humans, and who better than nature to shape the local population for survival?

siberia-womanRecently, a team of researchers at  University of Cambridge, working in close collaboration with researchers from the  Institute of Biological Problems of the North in Magadan, Russia, have performed the most extensive genetic survey in Siberia, analyzing genetic variants from ten groups that represent nearly all of the region’s native populations.

Their findings suggest specific genes helped  humans who have been living in Siberia for 25,000 years cope with the extreme cold. Three genes – UCP1ENPP7 and PRKG1, – were found to have undergone positive natural selection, based on specific techniques the scientists used to identify the genetic traits favored by evolution.

In a previous 2010 study authored by University of Chicago geneticist Anna Di Rienzo and her colleagues, only two Siberian populations were studied, still two genes were identified as being more active UCP1 and UCP3. These two gene help the body transform body fat directly into heat, without going through an intermediary step that transforms it into chemical energy first.

The other two genes ENPP7 and PRKG1 identified in the present study were also found to offer significant advantages to the Siberian natives. PRKG1 is involved in the contraction of smooth muscle, key to shivering and the constriction of blood vessels to avoid heat loss. ENPP7 is implicated in the metabolism of fats –  a great genetic trait considering the mostly fat-laden diets of the local populace comprised mostly of meat and dairy products.

Since this was an extensive study where more than 200 DNA samples from native groups spread through out Siberia, naturally some genes were expressed more in some groups than in others, which is why the University of Chicago might have missed a few in the first place. Thus selection for UCP1 was strongest in southern Siberian groups, while selection for PRKG1 was greatest in northeastern and central Siberia. ENPP7, on the other hand, showed strong selection throughout Siberia.

Evolution never sleeps and is a constant process. These latest findings serve as a reminder.

“The results are fascinating,” says Danae Dodge, a geneticist at the University of Sheffield in the United Kingdom, because they add to evidence that “we have continued to evolve in our modern world.”

via Science

Humanity is still subjected to the natural process of evolution, despite advances

Evolution, in very loose lines, is defined as the process which allows a species to survive by passing on the differentiating traits most likely to help offspring adapt to the world through means of natural and sexual selection. Considering the world around us has been shaped so much by human hand, a lot of people have questioned whether the natural process of evolution still applies to modern day humans. A research carried out by scientists in Finland concludes that the human evolutionary process is still well in place, and that we don’t necessarily need to study early hunter-gatherer communities from 10,000 years ago to understand how the human species evolved, and subsequently survived.

The environment we live in today has been almost completely artifically revamped. Advances beginning with the agricultural and industrial revolutions, have lead to significant advances which have shaped our way of life and made us less subsceptible to external natural stimuli, like diseases, hunger, and so on – at least in the parts of the world we like to call “civilized”. To see if all these factors have affected the billion-year old process of evolution, scientist  in an international collaboration, analyzed church records of about 6,000 Finnish people born between 1760-1849 to determine whether the demographic, cultural, and technological changes of the agricultural revolution affected natural and sexual selection in our species. Finland was an ideal choice for study material, since the country’s church has kept strict records of births, deaths, marriages, and wealth status, which were kept for tax purposes for centuries.

This relatively extensive data set allowed the researchers to form patterns and compare them with other species. The scientists looked at four key aspects that the agrarian industry of the time affected people, namely survival to adulthood, access to mates, mating success and fertility per mate. The scientists found that the modern farmers and fishermen of Finland responded to evolution much in the same way other species did as well.

Project leader Virpi Lummaa, of the department of animal and plant sciences, says: “We have shown advances have not challenged the fact that our species is still evolving, just like all the other species ‘in the wild’.

“It is a common misunderstanding that evolution took place a long time ago, and that to understand ourselves we must look back to the hunter-gatherer days of humans.”

Lummaa adds: “We have shown significant selection has been taking place in very recent populations, and likely still occurs, so humans continue to be affected by both natural and sexual selection. Although the specific pressures, the factors making some individuals able to survive better, or have better success at finding partners and produce more kids, have changed across time and differ in different populations.”

As for most animal species, the authors found that men and women are not equal concerning Darwinian selection.

Principal investigator Alexandre Courtiol, of the Wissenschftskolleg zu Berlin, adds: “Characteristics increasing the mating success of men are likely to evolve faster than those increasing the mating success of women. This is because mating with more partners was shown to increase reproductive success more in men than in women.

“Surprisingly, however, selection affected wealthy and poor people in the society to the same extent.”

Understanding how natural and sexual selection still affects modern humans, in a time in which culture and science seeks to surpass our biological needs is extremely important to understanding ourselves in the first place, and hopefully predicting what shape society and the human species as a whole might take in the future. The present research offers some clues and glimpses that suggest the impact of natural and sexual selection which affects all living organism on Earth still very much applies to humans as well, and should not be underestimated.

“Most scientists studying human evolution focus only on our hunter-gatherer way of life 10,000 years ago, but we show that, albeit interesting, this will not give you a complete picture of the story — we also need to focus on how people were living until very recently, and probably even today,” Courtiol added.

“Extending our research toward modern days would be particularly interesting to understand how the current environment continues to shape humans,” Courtiol said. “This could be potentially of importance from a medical point of view, to understand, for instance, how quickly our immunity can respond to new major epidemics. One major obstacle is that we need reliable data at the level of individuals — number of offspring, number of partners, birth and death date — across the lifetime of all born individuals, and such datasets are rare because even many famous longitudinal studies are biased towards certain types of people or do not cover all necessary life events.”

Their findings are published in Proceedings of the National Academy of Sciences (PNAS).

source: Futurity