More and More Humans Are Growing an Extra Artery, Showing We're Still Evolving (sciencealert.com) 111
An anonymous reader quotes a report from ScienceAlert: An artery that temporarily runs down the center of our forearms while we're still in the womb isn't vanishing as often as it used to, according to researchers from Flinders University and the University of Adelaide in Australia. That means there are more adults than ever with what amounts to be an extra channel of vascular tissue flowing under their wrist. "Since the 18th century, anatomists have been studying the prevalence of this artery in adults and our study shows it's clearly increasing," Flinders University anatomist Teghan Lucas said in 2020. "The prevalence was around 10 percent in people born in the mid-1880s compared to 30 percent in those born in the late 20th century, so that's a significant increase in a fairly short period of time, when it comes to evolution."
To compare the prevalence of this persistent blood channel, Lucas and colleagues Maciej Henneberg and Jaliya Kumaratilake from the University of Adelaide examined 80 limbs from cadavers, all donated by Australians of European descent. The donors raged from 51 to 101 on passing, which means they were nearly all born in the first half of the 20th century. Noting down how often they found a chunky median artery capable of carrying a good supply of blood, the research team compared the figures with records dug out of a literature search, taking into account tallies that could over-represent the vessel's appearance. Their results were published in 2020 in the Journal of Anatomy. The fact the artery seems to be three times as common in adults today as it was more than a century ago is a startling find that suggests natural selection is favoring those who hold onto this extra bit of bloody supply.
To compare the prevalence of this persistent blood channel, Lucas and colleagues Maciej Henneberg and Jaliya Kumaratilake from the University of Adelaide examined 80 limbs from cadavers, all donated by Australians of European descent. The donors raged from 51 to 101 on passing, which means they were nearly all born in the first half of the 20th century. Noting down how often they found a chunky median artery capable of carrying a good supply of blood, the research team compared the figures with records dug out of a literature search, taking into account tallies that could over-represent the vessel's appearance. Their results were published in 2020 in the Journal of Anatomy. The fact the artery seems to be three times as common in adults today as it was more than a century ago is a startling find that suggests natural selection is favoring those who hold onto this extra bit of bloody supply.
So what's it for? (Score:3)
Masturbation, intravenous drug use, typing, game controllers, touch screens, or suicide?
Re:So what's it for? (Score:5, Insightful)
intravenous
Clearly you're missing a key part of what this word means.
Re: So what's it for? (Score:2)
Re: So what's it for? (Score:3)
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it's not like pig eyed little trolls aren't spitting out kid after kid in the world.
Can't tell if this is sarcasm or serious
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We have been using more and more equipment with our hands. Some which needs a certain amount of dextrity to use properly.
From hunting / farming tools centuries ago, to now, mobile devices, computers, etc. Not to mention all the other tools we use, from vehicles to surgical tools to pressing buttons to call an elevator, to pretty much everything else. I am pretty sure you are using your hands to type in your msgs here as well.
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It might mean those more likely to be dextrous have better chance at a better life. Which means better chance of finding a mate, having kids, etc.
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Our hands are probably increasing their dexterity. I remember reading that we will probably end up with smaller bodies but bigger hands and eyes in thousands of years.
Absolutely ... this is exactly what happened to Gollum.
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flipping off trolls
Re:So what's it for? (Score:4, Funny)
It helps Australian bodies process iocane.
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I've spent years building up a tolerance to iocane powder.
And bagels
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If this trait was genetic and tripled in prevalence in one generation, that means people with that trait had 200% more offspring than people without the trait.
That is not plausible.
I don't know what the explanation is, but it isn't "evolution".
Re:So what's it for? (Score:4, Insightful)
Re: So what's it for? (Score:2)
Or maybe it's caused by watching TV.
Is it in the remote control hand?
Re:So what's it for? (Score:4, Funny)
Epigenetic, not genetic? (Score:2)
Isn't it more likely to be an epigenetic change, rather than a genetic one? That's a simpler explanation for how it happened so fast.
Once we determine that, then we can search more effectively for the cause.
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It's Intelligent Design, duh!
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I don't know what the explanation is, but it isn't "evolution".
Agree. Nutrition seems more likely. Beyond that, changes in activity. The title is misleading, of course. People aren't growing an extra artery, they're just keeping it rather than losing it. It's not quite clear exactly when humans have been losing it exactly. Sometime before adulthood, but it's not clear if it's usually pre-natal, in infancy, as a small child, in adolescence, etc. So, aside from nutrition, it could be from a reduction in the amount of manual labor. Maybe it supplies extra blood to the ext
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Or it may tend to be more prevalent normally, but comes with a disadvantage that doesn't matter as much. Over the generations this study shows, infant mortality has dropped a lot. The absolute critical need to do manual labor to be successful is reduced, so if such people have a harder time working fields, it matters less.
It could be linked to some other trait that is a positive selector.
It could even be just bad data in the old studies, which sometimes happens.
Re:So what's it for? (Score:5, Informative)
"What's it for" is very often a misleading question with evolution. Evolution is not a force, or a guide, etc. There is no "optimization" mechanism. "Survival of the fittest" is the simplified thing taught in schools, but it wasn't necessarily Darwin's only idea here, but it was pushed more by Wallace where it seems to have been promoted as the only variable of interest. But evolution is like math, there are lots of things going on and at it's heart there is just heredity; what genes get passed to the next generation. There are a lot of weird stuffs that happen in evolution that has nothing to do with being "fit" at all, and some features evolve that can make a species actually less fit.
Sure, at some level you need a certain amount of fitness to survive, and these features appear most strongly. But at some point a species has settled in, fewer predators, easier to escape the predators, etc. So the species may evolve something else; male birds may have elaborate plumage which does nothing except attract female birds, but they're not more fit for it and the plumage may actually be a hindrance. But all it takes for the evolution to happen there is for the bird with a slightly different plumage to attract females just ever so slightly more, so that those genes gets passed on slightly more.
So when someone says "what is this weird thing for?", I think it's the wrong question. More of interest is perhaps "how did this occur?" Too often I see a sort of grade school mentality that misunderstands evolution - like "what is the evolutionary purpose of grandmothers", which is just silliness because evolution doesn't have a "purpose", but the "reason" grandmothers exist may be because we're living longer. What's the "purpose" for blue eyes doesn't make as much sense as the reason being that this was a recessive trait that showed up more in the people's that lived up north, which also lost much of their melanin in order to absorb more vitamin D because there was less sunlight up there, and the blue eyes are just a side effect of a very complicated process.
So what is the reason this artery has been sticking around more often? That's the question. Possibly there is now a lot more interbreeding between peoples of disparate global regions; societies are less insular and can move around more. Say the 1800's studies were all on Europeans from a few countries, and they didn't have good numbers about people from Africa or Asia, but now society is a lot more mixed.
With dogs, it takes a long time to get a new breed. but it only takes a tiny handful of generations, maybe just 3 or 4, to revert to your generic yellow mutt with the curly tail.
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Optimization implies that you get reach a maximum, even a local maximum, and then you slow down or stop. But evolution is constant non-stop change. It's just change that's very slow to see. The basic mathematical function is simple: keep your genes alive. Or from a slightly higher viewpoint: create offspring that survive to create more offspring. So with evolution you never end up with a species that just stops and stays at the status quo forever. That species will eventually result in variants and su
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Optimization implies that you get reach a maximum, even a local maximum, and then you slow down or stop. But evolution is constant non-stop change.
That implies either that conditions are changing (cost function has changed) or the local minimum has not yet been achieved.
So with evolution you never end up with a species that just stops and stays at the status quo forever.
Some remain remarkably similar in terms of phenotype for millions of years, even if there are small ongoing changes in genotype. Speciation can be considered a bifurcation with a new item being attracted to a different local minimum.
If there is an optimization function, then that function is either always change, or there are many competing functions happening at the same time.
It's still a cost function, even if very complex.
It's like your genetic algorithms, but without a set of developers trying to train them in a certain direction but instead injecting lots of randomness and seeing where the chaos engine goes.
You don't necessarily train a genetic algorithm in a certain direction. In fact you don't as the idea is t
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"What's it for" is very often a misleading question with evolution. Evolution is not a force, or a guide, etc.
Leading to billions upon billions of failures, with it's wreckage littering the countryside. Just waiting for some enterprising scientist to find them. ;-)
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Hey, as someone with beautiful blue eyes, I object to your eye reasoning! My ancestors got laid, that's why I have blue sparkly eyes.
Selective Pressure (Score:2)
Using the term "selective pressure" https://catherinephamevolution... [weebly.com] I think would have made your post both less wordy and easier to follow as it took me a bit to figure out what you were even going on about.
Also, an unlikey recessive attribute like blue eye's sticking around in a modern context where white people don't really have vitamin D deficiencies anymore is likey more of a "plumage" scenario. I know I've gotten a lot of comments from ladies over my own blue eyes over the years.
Same with blond hair.
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Ya, I sort of went on a stream of consciousness there. Mixing together some things already in my mind, plus an old pet peeve about evolution simplification.
Note that the rules of attraction, in humans anyway, are changing rapidly. Fat is in, thin is in, a light skin versus a dark tan, a rugged physique versus lanky, etc. There's a societal element going on that affects this all as well. I think the same happens with animals - fashion that is. It's just that fashion is fast with humans but very slow to
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...plus an old pet peeve about evolution simplification.
Same. Quite a lot of people view evolution as some sort of leveling up that naturally just happens on its own and I find that a bit annoying as well :)
Note that the rules of attraction, in humans anyway, are changing rapidly. Fat is in, thin is in, a light skin versus a dark tan, a rugged physique versus lanky, etc. There's a societal element going on that affects this all as well. I think the same happens with animals - fashion that is. It's just that fashion is fast with humans but very slow to change with animals.
Absolutely. I'd like to add though that in the context of blond hair and blue eyes it may be a function of "bright things catch people's eyes" as opposed to the more fluctuating standards you mention. I've heard this idea put forward by a few different science teachers in both high school and college and read about it in a few places after the fact as well s
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Actually, given kin selection the question ""what is the evolutionary purpose of grandmothers?" is reasonable. It *may* not have an answer, but that's not the way to bet. It costs resources for a tribe to keep grandmothers around, so how does having grandmothers enable more great-grandchildren to survive? There are obvious answers, but many of them seem insufficient. One answer is "baby sitters". Another answer is "repository of useful knowledge". There are others, but they still don't obviously suffi
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Well, menopause happens because the biological systems age and break down. The female reproductive system is a lot more complicated than a male's and it involves more than just creating eggs but in nurturing and developing that egg until birth. More stuff to break down over time. Whereas creating and delivering sperm is a lot simpler, but even that breaks down over time (prostate troubles, anyone?). There doens't need to be a reason for this to happen, though the explanation can help find ways to slow o
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That explanation fails, because of the large number of animals that don't have menopause. And I wasn't talking about societal evolution, though of course that happens, but grandmothers happen before you get tribes that support useless members...or at least apparently so.
Grandmothers appear to have shown up after Homo erectus, and before Homo sapiens...though perhaps barely before Homo sapiens. That said, the evidence is quite fragmentary, and it's quite reasonable to not be convinced.
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Even if the extra blood flow is a net negative in terms of survival fitness, we as a society tend to take care of our ill and otherwise not so fit to survive naturally nowadays.
That may also increase selective pressure on evolutionary negatives to pass to the next generation.
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Well Masturbation, and Suicide probably not so much, one being a simple set of movements, and the other not aiding in evolution.
However actions that require more agile and fine motor control do indeed give us an advantage from over 100 years ago.
Where a hundred years ago, most of our actions were mostly large movements, hammering, screwing, shoveling... Our fingers were mostly used to just grab onto an hold stuff. Now that we use our fingers for typing, mouse movement (often with a high degree of accurac
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OK, so are these extra-artery people supposed to be our new rulers, or are they here to serve us?
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neither, they will replace us entirely. total extermination.
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Guitar/violin/piano? Extra blood flow to keep those fingers flailing!
Speed flipper .. (Score:2)
This doesn't seem logical (Score:5, Insightful)
How could such a minor difference, and even a potentially negative difference (TFA mentions greater susceptibility to carpal tunnel), cause such a massive genetic evolutionary shift in that microscopic time period? They're talking about 2-3 generations exhibiting a huge change..
Wouldn't it be worth exploring whether the presence in utero of certain hormones (or hormone-like chemicals), maternal nutrition, C-section/regular birth, radiation exposure, etc., made this artery more likely to remain?
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Carpel Tunnel mostly happens after primary reproduction age. Maybe it makes you a better athlete?
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It could be an artifact of a genetic downside, but we're saving more and more people with better treatments for everything.
Re:This doesn't seem logical (Score:4, Insightful)
I think it is more likely that better uterine conditions allowed a bit of overbuilding in anticipation of larger (or at least better-supplied) limbs. Bad house analogy: if you were building expensive housing in the 90s, you may have run Cat-5, but cheap houses just had POTS.
In any event, 78 limbs from Australians does not seem like a sufficient basis to believe we are witnessing evolution at work. But the article is paywalled, so maybe they make a brilliant case.
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Yep, I was thinking hormones and environmental toxins also.
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It likely isn't genetic at all. There is a very good chance that the larger limbs support enough flow that the artery doesn't go away as it is replaced by other ones. This artery was the 1st one that developed in the arm. Two more develop once there is enough mass to support them and this one usually goes away. There are other situations like the arteries that feed the kidneys as they move during fetal development. Some people now have two arteries feeding one kidney. That problem makes blood pressure
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Negative difference might be the clue. We are dying a lot less at a young age than we used to. Medical advances are causing natural selection to reverse its course.
Re:This doesn't seem logical (Score:5, Interesting)
The Black Queen hypothesis [wikipedia.org] is similar: when not under selective pressure, organisms evolve maximize their growth conditions. One way of interpreting this is that they no longer put in the "effort" to maintain their previous genetic profiles (since there's no negative feedback for failing to do so.) The BQH specifically concerns "cheating" behaviour, where part of a bacterial population stops producing a needed chemical because there's excess supply in the environment made by its cohorts, leading to a defective variant that can only survive as long as the excess supply is available. In this case it's reasonable to intuit that human diversity will continue to grow as medicine continues to provide a tolerant environment.
In this particular case, it's probably not genetic evolution at work. As other commenters have noted the sudden jump in frequency of this artery is implausible as a spontaneous mutation that just so happened to occur simultaneously in 20% of white Australians over the past century. More likely the artery's presence is correlated with miscarriages or infant mortality, perhaps simply because it costs extra energy to grow, and improvements in nutrition and sanitation have made it more tolerable. Genetically it might be as simple as a homozygous recessive allele—no new genes, just one copy of the same mutation inherited from mum and dad.
Incidentally, while in reality the Black Queen hypothesis predicts the evolution of symbiosis (as one "cheating" population emerges, it's free to specialize in providing other nutrients to the community and therefore encourage other populations to cheat in other ways, forming a dependent relationship) it also describes the spontaneous manifestation of specialization in economics, and underlines that upper classes can only come into being if there is enough productivity to allow them to cease being self-sufficient. This rather succinctly illustrates how Liberalism follows naturally from even the most minimalist description of the natural condition.
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In this particular case, it's probably not genetic evolution at work. As other commenters have noted the sudden jump in frequency of this artery is implausible as a spontaneous mutation that just so happened to occur simultaneously in 20% of white Australians over the past century.
Two problems with this take.
First, in common with many commenters here, is the error of thinking evolution is about mutation. The process of evolution is about, and only about, the change in gene frequencies in a population which can be due to selection, genetic drift, founder effects, etc. It acts on the genes that exist in a population. Mutation does introduce new genes, but nearly always these are immediately eliminated as they are deleterious. Mutations that are not deleterious may get acted upon by the
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Fear not, brave word-warrior. The answer is more interesting than that.
I'd like to think the sentence
which was at the end of that same paragraph, is the normal mechanism of selection in diploid organisms that you're outlining.
I agree that "genetic evolution" is a questionably pleonastic term in the context of the post as written. I qualified it like that because I w
Re:This doesn't seem logical (Score:4, Insightful)
How could such a minor difference, and even a potentially negative difference (TFA mentions greater susceptibility to carpal tunnel), cause such a massive genetic evolutionary shift in that microscopic time period? They're talking about 2-3 generations exhibiting a huge change..
It's definitely not due to selective pressure. Even if it had some advantage, it's not like that advantage would make individuals with this artery more likely to reproduce. Even if it were, say, correlated to some gene related to fertility, it wouldn't matter because humans have birth control and ways of dealing with fertility issues. Natural selection doesn't influence humans because we have detached ourselves from nature. Our selective pressures are sexual and cultural.
That doesn't mean we're not evolving. We will continue to change primarily due to genetic drift. Even in an environment that presents no selective pressures, sexual reproduction will lead to evolution because, functionally, it has randomness built in. Variation is the only constant. Obviously these changes are rarely as dramatic or happen as quickly as those influenced by selective pressures, but change happens nonetheless (one counter-intuitive thing that many people fail to consider is that genetic drift can actually make a species less "fit"). However, considering the colloquial sense of the word "evolution," the author of the headline should know that readers will misinterpret it.
Wouldn't it be worth exploring whether the presence in utero of certain hormones (or hormone-like chemicals), maternal nutrition, C-section/regular birth, radiation exposure, etc., made this artery more likely to remain?
Environmental conditions are certainly something that should be considered. If that's the case, it's not evolution at all.
From TFA:
Nailing down the kinds of factors that play a major role in the processes selecting for a persistent median artery will require a lot more sleuthing.
We shouldn't assume that any processes actually selects for this. It could be random, it could be environmental. The idea that it's related to some selective pressure seems to be the least likely explanation.
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Natural selection doesn't influence humans because we have detached ourselves from nature. Our selective pressures are sexual and cultural.
Also bacterial and viral. Modern medicine can blunt that ongoing war but not stop it. Despite our best efforts, we are still influenced by the microbial world. They're unavoidable. Indeed, we're utterly dependent on them. Our symbiosis with our intestinal bacteria isn't optional. You'll starve to death without their help.
We will never be completely detached from nature. Natural disasters still affect us. The change is microscopic, possibly even undetectable on traditional human timescales, but evolu
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You're right that bacteria and viruses warrant consideration. I started to comment on it and quickly realized that was a rabbit hole I'll need to research further.
Regarding the sexual dimorphism, war and slavery probably played important roles as well. There have been so many wars throughout human history that it must have applied some sort of selective pressure. For much of human history slaves were the spoils of war and when they were allowed to reproduce it was often done selectively. Rape was another sp
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Wouldn't it be worth exploring whether the ...
population of Australia is a representative sample?
Whether there were enough old people in the study to give a high confidence to these results? They only had 80 arms to examine. The oldest was 101.
The confidence of these results is probably like... 15%.
The abstract doesn't list the P value, which is paywalled. But they do claim that other literature establishes a P value of less than .001. Then they say, after removing biased studies, the P value is .018. This doesn't give me much confidence; why are the
Nutrition (Score:4, Insightful)
Wouldn't it be worth exploring whether the presence in utero of certain hormones (or hormone-like chemicals), maternal nutrition, C-section/regular birth, radiation exposure, etc., made this artery more likely to remain?
It could be as simple as nutrition. People today are much taller than in the 1800s, and we know it wasn't evolution. We are now much better fed and are provided all the nutrients we need. I imagine that the retention of this artery is related in some way. Perhaps because our limbs are longer the artery tends to be retained more often now, or the lack of proper nutrition in the womb affects various structures, including the formation of this artery.
Re: This doesn't seem logical (Score:2)
Agreed.
Evolution is the non random selection of traits beneficial to survival (or more specifically, successful breeding) from random changes...It's like discerning a picture out of static.
There is precisely zero chance that preferential advantages of any mutation would be discernable within a human life time, much less be expressed in physiology.
Vastly more likely we're seeing a hormonal result of something abundant in western human diets/lives since 1900.
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Evolution is the non random selection of traits beneficial to survival (or more specifically, successful breeding) from random changes..
Random processes - genetic drift and found effects - are part of evolution also, important parts in fact. The random processes are largely responsible for geographic speciation, geographically separated populations becoming different species over time. This happens even in the absence of selective pressure.
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Note that the potentially negative difference can do it, if the disadvantage doesn't matter anymore.
If people with this trait in pre-industrial times tended to not be able to work fields well, then they wouldn't exactly be impressive people in their communities.
In the modern era, a pencil pusher can be quite successful, so the drawback is more minor and the trait can flourish more without the negative pressure.
We trend toward diverse genetics absent of particular pressure one way or another, so a rare trait
Bloody wankers (Score:2)
Environmental toxins? (Score:2)
I wonder if its all the toxic chemicals in the environment that are causing that, altering hormones. It doesnt really make sense for it to be evolutionary.
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Toxic chemicals? No. As a general rule our environments are *much* healthier than our predecessors due to modern hygene.
And no nothing has changed in our hormones. Its a popular myth amongst alt-right people , buuuut thats an unusually gullible cohort, so thats no surprise. These are the same people that ran about claiming that Trump was leading some sort of spooky covert ops team to take down a vast conspiracy of evil canibals building underground mole-children cities under pizza shops, and yeah literally
Mutation (Score:2, Insightful)
This isn't evolution -- there's no natural selection that favors survival of those with an extra artery in their forearm, I'm guessing.
Instead, this is a mutation. Mutations come, mutations go, and they probably aren't usually the same for a group of people. (Don't the anti-evolutionists that say there's no way that a whole group would have the same mutation in the same way? What's this?) Even so, they may not usually be the same, but there could be something environmental causing the development in a whole
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How can a mutation be widespread if not for evolutionary pressure? Mutations occur randomly, but when we see some of those mutations being preserved and perpetuated that means it's evolutionary pressure. It's not like they found one person with the mutation and declared it as evolution. They found a large number of unrelated individuals with it.
I don't think so (Score:2)
Evolution doesn't happen without people dying. Unless people are dying due to lack of an artery in their arms, it's unlikely this is due to evolution. Did they check if the ethnic group of the participants is different in the different studies? I'll bet not. Most likely the ethnic group in each study was somehow different.
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Wrong. Evolution happens when there is a difference in reproductive success.
Dying will definitely affect your reproductive success.
But it is far from the only factor.
But I agree: the assumption that the increase is due to hereditary factors is quite a leap.
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Yes true, fair enough. I'm not seeing more artaries in your arm affecting your reproductive success either.
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Cause (Score:2)
If the retention is tied to some environmental or developmental conditions, then it's not really evolution as such (not on its own anyway) - just an individual response to environment occurring more commonly.
Of course, it could be buried in a journal paper somewhere but I'm not inclined to do that much digging for it right now.
fallacies (Score:2)
comparing French bodies of centuries ago to "european" ones of today from a different country, apples and kumquats.
Maybe some European groups always had higher incidence than others.
Methodology (Score:3)
To compare the prevalence of this persistent blood channel, Lucas and colleagues Maciej Henneberg and Jaliya Kumaratilake from the University of Adelaide examined 80 limbs from cadavers, all donated by Australians of European descent. The donors raged from 51 to 101 on passing, which means they were nearly all born in the first half of the 20th century. Noting down how often they found a chunky median artery capable of carrying a good supply of blood, the research team compared the figures with records dug out of a literature search, taking into account tallies that could over-represent the vessel's appearance. Their results were published in 2020 in the Journal of Anatomy. The fact the artery seems to be three times as common in adults today as it was more than a century ago is a startling find that suggests natural selection is favoring those who hold onto this extra bit of bloody supply.
Just to be clear, their assertion is that *so many* people without this artery died before reproductive maturity or were otherwise unfit to reproduce, that over the course of a few generations their relative proportion dropped from a 9x representation in the population to a 2x representation. This is concluded entirely from a difference of sixteen people in a group of eighty Australians who meet some fairly unique criteria (parents didn't interracially marry, died at 50+, wanted to donate their bodies to science) and googling other papers from people a hundred years ago (who definitely used the same process and had the same training!) For this, they estimate a p value of .0001.
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To compare the prevalence of this persistent blood channel, Lucas and colleagues Maciej Henneberg and Jaliya Kumaratilake from the University of Adelaide examined 80 limbs from cadavers, all donated by Australians of European descent. The donors raged from 51 to 101 on passing, which means they were nearly all born in the first half of the 20th century. Noting down how often they found a chunky median artery capable of carrying a good supply of blood, the research team compared the figures with records dug out of a literature search, taking into account tallies that could over-represent the vessel's appearance. Their results were published in 2020 in the Journal of Anatomy. The fact the artery seems to be three times as common in adults today as it was more than a century ago is a startling find that suggests natural selection is favoring those who hold onto this extra bit of bloody supply.
Just to be clear, their assertion is that *so many* people without this artery died before reproductive maturity or were otherwise unfit to reproduce, that over the course of a few generations their relative proportion dropped from a 9x representation in the population to a 2x representation. This is concluded entirely from a difference of sixteen people in a group of eighty Australians who meet some fairly unique criteria (parents didn't interracially marry, died at 50+, wanted to donate their bodies to science) and googling other papers from people a hundred years ago (who definitely used the same process and had the same training!) For this, they estimate a p value of .0001.
I would also put this paper in the "may turn out to be wrong or at least exaggerated" bucket in spite of their low p value: https://www.newscientist.com/a... [newscientist.com]
This is probably epigenetic (Score:2)
Google it. There's no way DNA evolution could work in a few generations on so many people , there simply hasn't been enough mixing of the human genome between people over that time. This is most likely epigentic - we're using our hands more so more blood is required and hence this is favoured in future generations. Or at least thats my take on it, feel free to calll me out. But if you can think of another reason please post.
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Exactly. Just like with teeth. As our diets change from heavy use of raw grains and root fibers to more processed food, we don't use our wisdom teeth and our jaws don't have enough room, but if we grow up in an area where diet favors grains and roots, you tend to have a larger jaw.
It's not evolution, just adaptation.
I'd be wary to talk about evolution in humans (Score:2)
We have shed evolution and replaced it with civilization. Evolution would eliminate a lot of hereditary diseases or at the very least make them even rarer than they are simply by causing an early elimination of those with it. That's not to say we should do that, far from it, only that evolution has little impact on the development of modern human anymore.
Hell, even for the animals we breed, "natural" selection is a thing of the past. What we have here is artificial selection, i.e. ours. We breed animals tha
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We have shed evolution and replaced it with civilization. Evolution would eliminate a lot of hereditary diseases or at the very least make them even rarer than they are simply by causing an early elimination of those with it. That's not to say we should do that, far from it, only that evolution has little impact on the development of modern human anymore.
Evolution is not what you seem to believe it is. It is still working just fine. It is just that our environment has changed so that other factors are more important now than what used to be important.
Child mortality (the risk that a child dies before it is 5 years old) is now close to 4% globally (~10% in the worst hit countries) compared to 40-50% a few generations ago. By far the most of this reduction is due to less starvation, better living conditions and better health services across the globe. This me
Beef (Score:2)
Ironic, given a beefy forearm suggests a lower risk of pregnancy from semen release incidents.
Sample bias, clearly. (Score:2)
Data from 1800 is anecdotal, and estimated.
Sample bias is a more likely explanation than genetic variation.
Re: (Score:2)
Behold the power of the mighty Coriolis force! (Score:2)
-or possibly of Vegemite
We are still evolving, there is better evidence. (Score:5, Insightful)
But there is better evidence that H sapiens are still evolving. Sickle cell anemia and lactose tolerance are decent examples.
Sickle cell anemia prevalent mostly among Africans is a fatal disease when both chromosomes get the mutation affecting the red cells. But if, only one chromosome gets the mutation, it provides some protection against malaria. Very clearly a genetic variation has been presented and evolution is applying its natural selection. At some point another mutation will happen that will remove the deleterious effect of both chromosomes getting the sickle-cell allele. Then that allele will get "fixed" and there will be a sub-race of humans who are immune to malaria. Eventually it might spread to entire human genome. Or it might never gets fixed, but continue for a long time like the hemophilia. It is probably not the first attempt by human genome to find immunity from malaria.
Lactose tolerance is very new. It is less than 6000 years old. Originated in Western Europe, around Holland. This mutation allowed humans to consume milk in adulthood. Milking a cow extracts 10 times the calories one can compared to slaughtering it. Slaughtering it after its milking life is done still gets some beef calories, albeit less tasty beef. This led to differential population growth among lactose tolerant people. It is found among Indo-Europeans. There is another lactose tolerant mutation in sub-saharan Africa, originating in another herding tribe. Left to nature, lactose tolerance will reach all the humans. This is another example that we are still evolving.
Compared these arguments, this additional artery is not much. We are finding it because we are looking for it.
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I don't disagree, but I find these two statements from TFA contradictory:
* More And More Humans Are Growing an Extra Artery, Showing We're Still Evolving
* An artery that temporarily runs down the center of our forearms while we're still in the womb isn't vanishing as often as it used to
So which is it? Are we growing an extra one, or failing to discard an existing one? "Growing extra" implies that this is a new thing that previously didn't exist.
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Perfect example is lactose tolerance. It exists in all babies. But as they grow older they lose the ability to digest lactose, the sugar in milk. But some humans retain the ability to digest milk. It is very high in Holland, nearly 95% are lactose tolerant, and falls as you go far from Holland, and drops to something like 65% among
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Thank you, that is better than that artery thing ...
Add to the list the various adaptations for high altitude that developed separately, using separate mechanisms in the Tibet, Ethiopia, and Andes.
There is also the Bajau who adapted to fishing underwater.
Misconceptions about evolution. (Score:1)
Nothing says we're necessarily evolving with that vein. That's not how evolution works. It does not have to be "for" something.
Everything where there's no relevant or stable evolutionary pressure, can randomly mutate at will. No need for it to be advantageous.
So unless we actually know it's advantageous, the correct description is merely, that it's a mutation.
My bro has two mutations himself. One disadvantageous one that makes him unable to grow fat reserves that keep him warm, (which got him girls anyway,
Sample size not large enough (Score:2)
And this is why I only drink filtered water (Score:1)
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Most of the bottled water people in the US drink is actually from my city's water supply. It's just our tap water, but it's clean and we have a lot.
Very interesting (Score:2)
Wisdom teeth too (Score:2)
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This is more based on your diet. If you eat roots and hard fibers at an early age, your jaw will adapt and your wisdom teeth will continue to be useful and have space on your jaw to grow. I grew up on tree farms and ate a lot of things that involve more chewing, so there's room for my wisdom teeth, but many other people eat more processed (soft) foods.
It's not evolution per se, just adaptation to use. If you lived in space, same thing would happen.
Maybe lack of negative influence (Score:1)
Just an adaptation to computing (Score:2)
We are using our hands and fingers more and more over the past millennia.
Non-genetic reasons (Score:2)
The comments in the replies here as well as the original article all imply a genetic mechanism or evolution, but while that could be true, it most likely is not the case.
The median artery is a normal structure. In clinical surgery, we have long recognized problems related to "persistent median artery". It is not common, but not rare either. Key is the word "persistent". That artery arises embryologically. It is there to start with early in embryogenesis. For most people, it atrophies or becomes vestig
Not evolution (Score:2)
"Showing we're still evolving" (Score:2)
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Sorry, that is utter nonsense.
Proof: Blue whale.