[HN Gopher] Forearm artery reveals human evolution continues?
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Forearm artery reveals human evolution continues?
Author : happy-go-lucky
Score : 62 points
Date : 2020-10-10 18:36 UTC (4 hours ago)
(HTM) web link (news.flinders.edu.au)
(TXT) w3m dump (news.flinders.edu.au)
| rthomas6 wrote:
| Could this be an epigenetic/gene expression change caused by
| increased use of our forearm and hand muscles? For instance, how
| I'm typing this right now, and how children write a lot more than
| they used to.
| sradman wrote:
| From the paper's Introduction:
|
| > The regression of the median artery commences at
| approximately the eighth week of intrauterine life. However,
| the median artery persists in a considerable number of foetuses
| of gestation ages 13-38 weeks, in newborns and infants and in
| adults.
|
| I'm guessing no to epigenetics unless it involves a change in
| the intrauterine environment.
| mci wrote:
| I have procured a PDF of the paper. Ctrl+F race finds nothing in
| it. The authors treat e.g. these results equivalently:
|
| * Adachi, B. (1928) Das Arteriensystem der Japaner. Kyoto, Japan
| (8.00%)
|
| * Kodama, K. (2000) Arteries of the upper limb. Tokyo, Japan
| (8.2%)
|
| * Henneberg, M. and George, B.J. (1992a) High incidence of the
| median artery of the forearm in a sample of recent South African
| cadavers (27.10%)
|
| * Cheruiyot, I. et al. (2017) Prevalence and anatomical patterns
| of the median artery among adult black Kenyans (59.68%)
|
| To me, a more plausible explanation is: "as time passes,
| anatomical studies cover more diverse humans".
| x86_64Ubuntu wrote:
| I'm confused about why you would CTRL+F "race".
| danieltillett wrote:
| But this hypothesis is not going to get you sexy headlines and
| your next grant funded. If we don't fix the problems with grant
| funding and the resulting imperative to publish or perish we
| are going to kill science.
| tyre wrote:
| With a limited pool of funding, how would you decide?
|
| If a committee, how would they be chosen, guarding against
| bias, etc.
| danieltillett wrote:
| This problem has been solved long ago. Screen all grant
| applications to weed out the flawed approaches (the bottom
| 25%) and then run a lottery on the remaining. If there is
| nothing to game, the gaming stops.
| bonoboTP wrote:
| But it goes way deeper than just grants. Who will get
| tenure for example? Citations and publication counts are
| used for many many things. Also, making your findings
| sexy is not just done to improve metrics for promotion
| and grants. Sexy research also draws attention among
| experts and lay media alike. They will be invited to give
| talks at conferences and seminars etc. more if their
| findings are exciting.
| tgbugs wrote:
| I work with a consortium that is trying to map the anatomy of
| the peripheral nervous system. My key take home has been that
| our knowledge of peripheral anatomy at population scale is
| woefully inadequate. People look at Vesalius and think "oh,
| that was settled 500 years ago," but as it turns out it seems
| that we know far more about the peripheral anatomy of our pets
| and domestic animals than we do about our own.
| sradman wrote:
| Is there a non-intrusive (and hopefully inexpensive) imaging
| technique that can be used on a living population rather than
| depending on cadaver dissection? Doppler, ultrasound, or even
| modified consumer wrist reflective PPG (like in the Apple
| Watch) should be able to detect the median artery. I imagine
| nerves are harder to map.
| tlarkworthy wrote:
| MRI can measure blood flow (not cheap though)
| mci wrote:
| I once tried to write an algorithm cookbook where the network
| flow problem would be illustrated by a simplified human
| circulatory system and its edge capacities -- by the
| diameters of the major blood vessels (this is how I knew to
| look for Adachi in this paper).
|
| Besides the diameters being different in autopsies and
| ultrasounds, it turned out that while the mean diameters of
| the arteries are generally known, as they are used for
| diagnosing aneurysms, no source I found cared to publish the
| mean diameter of, say, the left and right gastroepiploic
| veins.
|
| Also, even if 90% of people have the prevalent topology of
| some branching of blood vessels and only 10% have other
| variants, there are so many branchings that hardly anyone has
| a "textbook" circulatory system (that is, if the branchings
| are independent; I have seen no study of their correlations).
| sradman wrote:
| > The focus of this study was not to analyse the prevalence of
| the occurrence of the median artery in relation to ethnicity,
| geographic origin or variations by sex, but to identify the
| global trends in its occurrence.
|
| Hopefully this paper will inspire more research involving this
| interesting phenotype. I'm curious about the population
| specific prevalence too.
| bonoboTP wrote:
| Do I understand correctly that their observations are
| compatible with the possibility that some ethnic groups have
| more of this phenotype and these ethnic groups are becoming a
| larger percentage of the world population in general? This
| would make the story about the artery a red herring.
|
| For example if Northern Europeans started reproducing at a
| higher rate, could we say that humanity is evolving more and
| more lactose tolerance? I would say that would be very
| misleading.
|
| My question is, does their methodology tell apart the
| following effects:
|
| - The new artery is spreading across the board in various
| places, e.g. there is a general environmental selection
| pressure for random mutations in this direction, OR
|
| - Populations that have it or don't have it are reproducing
| at different rates, possibly for totally unrelated reasons
| like socioeconomic ones.
| mci wrote:
| > My question is, does their methodology tell apart the
| following effects: [...]
|
| First and foremost, their curve fitting, disguised as race-
| agnostic methodology, ignores the number of studies of the
| median artery in Africa 100 years ago (zero) and now
| (many).
| carbocation wrote:
| The selection pressure on three versus two arteries feeding the
| hand has to be so incredibly small (in terms of survival to
| reproduction in humans) that I am having a hard time imagining
| how this story has any causal plausibility.
|
| _Edit_ to be more clear about what in the article I 'm
| responding to, it's this:
|
| > Dr Teghan Lucas from Flinders University says ... "This
| increase could have resulted from mutations of genes involved in
| median artery development or health problems in mothers during
| pregnancy, or both actually. If this trend continues, a majority
| of people will have median artery of the forearm by 2100."
| Retric wrote:
| DNA isn't so neat as to cleanly separate every change. Thus
| this could be related to a host of changes that collectively
| represent a noticeable advantage. With circulatory issues being
| the #2 killer in the US it's likely for the circulatory system
| to be undergoing rapid change.
|
| Increased blood flow to the hand may mean a more efficient
| circulatory system increasing athletic performance and lowering
| disease risks etc.
| carbocation wrote:
| I agree. There are plenty of reasons why this could be
| happening, including reasons that have nothing to do with any
| sort of selection at all. I've updated my comment to clarify
| what I'm responding to.
| learc83 wrote:
| > #2 killer in the US it's likely for the circulatory system
| to be undergoing rapid change.
|
| Primarily killing people past reproductive age though.
| HNAwayGone wrote:
| Those people still influence the young, though. They have a
| huge impact on their young childrens' diets and habits, and
| I think epigenetics can throw a wrench into things by
| affecting how genes are expressed based on environmental
| factors.
| learc83 wrote:
| If you're talking about a mutation that will increase the
| reproductive success of your children(or more likely
| grandchildren in the case of reduced chance of a heart
| attack), then the advantage would have to be even greater
| because of the high chance that your descendants don't
| have the same mutation.
|
| I'm not saying there's no natural selection occurring,
| but that saying that heart disease is the #2 killer of
| Americans out of context likely overstates the selection
| pressure heart disease causes.
| [deleted]
| yarg wrote:
| Does it also impact fertility?
| Retric wrote:
| Heart disease can impact cognitive function, fertility,
| economic status, etc well before death.
| eecc wrote:
| Well, Natural Selection doesn't necessarily mean that only
| advantageous genes survive the Darwinian hustle, it can also
| mean that in the absence of negative external pressure also
| neutral variations are not systematically culled.
|
| It's like living in a civilized society; you don't have to
| worry of starving tomorrow so you take on making art...
| lopmotr wrote:
| It seems like we're on a terrible path with this absence of
| evolutionary pressure. What's happening to all the babies who
| survive today that would have died in childbirth had they
| been born at any time in human history before 100 years ago?
| Since infant mortality was so high, it must have been an
| close battle for evolution to keep it under control. Now the
| brakes are off and whatever mutations were regularly killing
| babies (and mothers) are now free to propagate to subsequent
| generations.
|
| Not that that's necessarily a bad thing. We've already
| evolved to become dependent on technology (cooking, clothing,
| shelter) and it probably does us good by freeing up our
| body's resources to do other things better. So perhaps
| becoming dependent on healthcare for childbirth will
| eventually happen too and nobody will be worried when women
| can only give birth by C-section or whatever.
|
| A related issue is immunization. People are so worked up
| about the politics that they don't want to think about this,
| but could it be that immunizing ourselves is taking away the
| evolutionary pressure to maintain a good natural immune
| system? Multiple generations of measles vaccinated people
| might end up like the native Americans who were vulnerable
| from their ancestors having never experienced measles.
|
| This seems like a whole alternative kind of morality -
| protection of the genes of future generations. But it goes
| against the popular short term moralities that people have so
| it seems too objectionable.
| carbocation wrote:
| Yes, I agree. I'm mostly responding to the authors'
| speculation:
|
| > "This increase could have resulted from mutations of genes
| involved in median artery development or health problems in
| mothers during pregnancy, or both actually. If this trend
| continues, a majority of people will have median artery of
| the forearm by 2100."
| cm2187 wrote:
| Similar evolution with no selection pressure:
|
| https://www.independent.co.uk/news/science/wisdom-teeth-evol...
|
| I don't think Darwinism is scientifically established. It has
| become a bit of a sacred cow because of its opposition with
| religion, but it is merely a good explanation compatible with
| the data. That doesn't prove it. It may be that life evolves
| and adapts through other mechanism than mere selective
| pressure.
| mrfusion wrote:
| I've always wondered that. Like why hasn't evolution itself
| evolved as well?
| slickrick216 wrote:
| Selection pressure probably doesn't apply to evolution in the
| present tense as evolution is not a conscious entity.
| Survival of the fittest could have only a past tense
| application ie the cause of evolution traits surviving. In
| this case evolution doesn't know if 3 arteries is good or bad
| it just happens those people have more kids and their kids
| have more kids until one day all the 3 artery people die
| because of some disease where having 3 arteries means you are
| more likely to die. This will leave 2 artery people living on
| and from their perspective looking back it's then selection
| pressure.
| cm2187 wrote:
| You are assuming this is completely random, and perhaps it
| is. But the evolutions about wisdom teeth for instance seem
| logical.
| slickrick216 wrote:
| Yeah maybe I don't know how that could happen though.
| Epigenetics maybe?
| rationalfaith wrote:
| Why would mutations ever stop? Also evolution is used ad nauseum
| it's annoying. Is cancer mutation evolution? Are hereditary
| sicknesses evolution?
|
| Mutation seems more objective and neutral term here.
| drbojingle wrote:
| Why would it stop?
| robbomacrae wrote:
| Bingo. If anything it would speed up with the population bloom
| and given society has A: changed our selection priorities and
| B: made it easier to survive allowing dna to jump out of the
| local minima we might otherwise be stuck in. Being able to
| afford for a few steps up hill might find a new valley with a
| deeper minima.
| Ericson2314 wrote:
| > Humans haven't developed mutations or superpowers just yet, but
| a new study shows our species is still evolving in unique ways
| and changes in natural selection could be the major reason.
|
| Ewwww. Why is university press the worst? If we are still
| evolving and this isn't just about genetic recombination then by
| definition mutations are involved.
|
| Also the publicist writes
|
| > This evolutionary trend will continue in those born 80 years
| from today, with the median artery becoming common in the human
| forearm.
|
| Wat. "Evolutionary intertia" probably has been defined by
| someone, but it's not that.
|
| It looks like this is a doubl-wammy misinterpration of the
| following quote, also from the press release:
|
| > "This increase could have resulted from mutations of genes
| involved in median artery development or health problems in
| mothers during pregnancy, or both actually. If this trend
| continues, a majority of people will have median artery of the
| forearm by 2100."
|
| It _could_ involve mutations and the trend _could_ continue.
| ffhhj wrote:
| "Evolutionary intertia"? Evolution is change, and inertia is
| the resistance to change... it makes no sense anyway.
| iheartblocks wrote:
| This seems rather dubious to me; what selection pressure exists
| that's increasing fitness for people with three arteries? The
| fact that it's progressing so rapidly suggests that this is
| either bad data, or environmental changes
| ceejayoz wrote:
| Right from the article:
|
| > Senior author Professor Maciej Henneberg who is also a member
| of the Institute of Evolutionary Medicine at the University of
| Zurich, Switzerland, says the median artery offers benefits
| because it increases overall blood supply and can be used as a
| replacement in surgical procedures in other parts of the human
| body.
| dghughes wrote:
| >because it increases overall blood supply
|
| But that's what I want explained why is more blood beneficial
| for a person's forearm?
|
| I don't feel like I am lacking blood flow during my daily
| tasks in life. Can "extra arm artery mutant guy" out-compete
| me in a specific task so critical it means his genes are more
| likely survive than mine are?
| fleischhauf wrote:
| Replacement makes sense, your friend with extra artery will
| survive in case of a critical surgery and might have
| another kid while you'd die with no extra kid. Does not
| need to happen to you but on average. Your friend with
| better bloodflow might also have a stronger erection and
| therefore on average more kids (pulling this out of my ass
| obviously). You dont need to have any obvious
| disadvantages, on average it might still work better..
| learc83 wrote:
| If we're talking about a trend strong enough that most
| humans will have this trait in 80 years, then if natural
| selection is driving it, none of those advantages are
| great enough to explain that.
|
| The most likely answer is that natural selection isn't
| directly driving this specific trait.
| [deleted]
| Someone wrote:
| I would guess extra blood flow could somewhat prevent
| people from suffering of cold fingers. I couldn't find
| evidence for that, though.
|
| Worse, Wikipedia claims it's easier to commit suicide by
| slashing your wrists if you have this artery
| (https://en.wikipedia.org/wiki/Median_artery), and
| https://radiopaedia.org/articles/persistent-median-artery-
| of... says it can be a cause of carpal tunnel syndrome.
|
| I don't see how either could be an evolutionary advantage.
| leephillips wrote:
| More stamina when composing romantic emails - greater
| chance of reproduction.
| fleischhauf wrote:
| So this means evolution actually reacted on progress on
| medicine and we are evolving our own spare parts for surgical
| procedures. While this makes sense im still amazed!
| Gupie wrote:
| But that does not increase, in any way significantly, a
| person's reproductive success.
| Someone wrote:
| That second part seems unlikely to me. I would guess the
| percentage of people that's beneficial to is extremely low.
| knolan wrote:
| That's not exactly a selection pressure. It would seem likely
| that there is no selection pressure here but in fact greater
| genetic diversity due to overall better survival of more and
| more people.
|
| Perhaps those that developed differently to have this artery
| retained were selected against in less civilised times.
| heeen2 wrote:
| There doesn't need to be selection pressure for a mutation to
| spread, it just needs to be no disadvantage to develop it
| pfdietz wrote:
| With no selection pressure a gene will not from 10% to 30% in
| a few generations. That requires a tremendous selective
| advantage.
| tronbabylove wrote:
| I also find this shocking - 10% -> 30% seems like a massive
| change in ~100 years in the context of human evolution.
|
| Why does increased blood supply create such a large selection
| pressure? And what type of surgical procedure uses the median
| artery as a replacement part?
|
| I have zero training in biology, so I think my mental model
| must be very off.
| fs_tab wrote:
| If you're interested in the study or its methodology, you can
| request the paper directly from the authors at:
| https://www.researchgate.net/publication/344230933_Recently_...
|
| According to the abstract, there has been a significant
| (p-value of under 0.001) increase in the prevalence of mid-arm
| arteries over time, which has been corroborated by multiple
| studies.
|
| After removing studies that focus specifically on the
| evolutionary aspect of this change, the p-value is 0.018, which
| still suggests a correlation.
| oh_sigh wrote:
| No need to request: https://scihubtw.tw/10.1111/joa.13224
| lehi wrote:
| _> "Other examples of human anatomy changing over time, include
| the prevalence of spina bifida occulta (opening of the sacral
| canal), abnormal connections of two or more bones in feet,
| increasing absence of wisdom teeth, thyroidea ima artery (branch
| of the aortic arch) - decreased over time, disappeared completely
| by the end of the 20th century) and fabella (small bone in the
| back of the knee joint - increased over time)."_
|
| Many of these, and the headline artery, appear to be newly
| retained neotenous traits and/or atavisms. It reads similarly to
| a list of physical differences between domestic dogs and wolves.
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