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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 ha

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 6y ago
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 6y ago
  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 6y ago
  > #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 6y ago
    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 6y ago
      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 6y ago
    [deleted]
  - yarg 6y ago
    Does it also impact fertility?
    - Retric 6y ago
      Heart disease can impact cognitive function, fertility, economic status, etc well before death.
      - learc83 6y ago
        Yes, but the vast majority of people who die from heart disease don’t develop it until they are older. Which is why it’s misleading to talk about it being America’s #2 cause of death when discussing evolutionary pressure.
        Retric 6y ago
        Heart disease starts at a young age. Mentioning deaths is relevant to demonstrate how common it is, not that the only impact is death.
        learc83 6y ago
        No it doesn’t. At least not normally. Google the prevalence rates of heart disease in people under 40. About 0.6% of people under 40 have the most common type of heart disease https://www.heart.org/idc/groups/heart-public/@wcm/@sop/@smd/documents/downloadable/ucm_449846.pdf https://www.heart.org/idc/groups/heart-public/@wcm/@sop/@smd... Again pointing out that it is the 2nd most common killer vastly overestimates its evolutionary impact. The same is true of cancer.
        Retric 6y ago
        Normal blood pressure increases steadily with age. https://www.idealbloodpressureinfo.com/blood-pressure-chart-by-age/ https://www.idealbloodpressureinfo.com/blood-pressure-chart-... Target and maximum heart rates similarly decline from your teens. The point where these get called a precursor to heart disease is largely semantics. But they do impact heath before it’s noticeable as a problem.
eecc 6y ago
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...
- carbocation 6y ago
  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.”
- lopmotr 6y ago
  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.
  - 6y ago
cm2187 6y ago
Similar evolution with no selection pressure: https://www.independent.co.uk/news/science/wisdom-teeth-evolution-humans-flinders-university-processed-food-b907634.html 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 6y ago
  I’ve always wondered that. Like why hasn’t evolution itself evolved as well?
  - ncmncm 6y ago
    What has led you to believe that evolution is not itself continuously evolving in each lineage? What do you imagine DNA is for? What do you imagine sex is for? Do you imagine that sexual reproduction always existed, or that it has had no effect on the lineages where it occurs, or their relative prevalence? How do you imagine those lineages became so prevalent, among multicellular organisms?
  - Barrin92 6y ago
    evolution itself does evolve. Eusociality or sexual dimorphism, group dynamics and all kinds of complex phenomena obviously weren't present in the primordial soup but are pathways themselves carved out by evolution. Rate of mutations may change, new mechanisms of evolution may turn up, humans ironically by understanding our genome have acquired the ability to manipulate it in intelligent fashion, and so on.
- slickrick216 6y ago
  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.

Retric 6y ago

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 6y ago
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 6y ago
> #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 6y ago
  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 6y ago
    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 6y ago
  [deleted]
- yarg 6y ago
  Does it also impact fertility?
  - Retric 6y ago
    Heart disease can impact cognitive function, fertility, economic status, etc well before death.
    - learc83 6y ago
      Yes, but the vast majority of people who die from heart disease don’t develop it until they are older. Which is why it’s misleading to talk about it being America’s #2 cause of death when discussing evolutionary pressure.
      - Retric 6y ago
        Heart disease starts at a young age. Mentioning deaths is relevant to demonstrate how common it is, not that the only impact is death.
        learc83 6y ago
        No it doesn’t. At least not normally. Google the prevalence rates of heart disease in people under 40. About 0.6% of people under 40 have the most common type of heart disease https://www.heart.org/idc/groups/heart-public/@wcm/@sop/@smd/documents/downloadable/ucm_449846.pdf https://www.heart.org/idc/groups/heart-public/@wcm/@sop/@smd... Again pointing out that it is the 2nd most common killer vastly overestimates its evolutionary impact. The same is true of cancer.
        Retric 6y ago
        Normal blood pressure increases steadily with age. https://www.idealbloodpressureinfo.com/blood-pressure-chart-by-age/ https://www.idealbloodpressureinfo.com/blood-pressure-chart-... Target and maximum heart rates similarly decline from your teens. The point where these get called a precursor to heart disease is largely semantics. But they do impact heath before it’s noticeable as a problem.

eecc 6y ago

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...

carbocation 6y ago
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.”
lopmotr 6y ago
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.
- 6y ago

cm2187 6y ago

Similar evolution with no selection pressure: https://www.independent.co.uk/news/science/wisdom-teeth-evolution-humans-flinders-university-processed-food-b907634.html 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 6y ago
I’ve always wondered that. Like why hasn’t evolution itself evolved as well?
- ncmncm 6y ago
  What has led you to believe that evolution is not itself continuously evolving in each lineage? What do you imagine DNA is for? What do you imagine sex is for? Do you imagine that sexual reproduction always existed, or that it has had no effect on the lineages where it occurs, or their relative prevalence? How do you imagine those lineages became so prevalent, among multicellular organisms?
- Barrin92 6y ago
  evolution itself does evolve. Eusociality or sexual dimorphism, group dynamics and all kinds of complex phenomena obviously weren't present in the primordial soup but are pathways themselves carved out by evolution. Rate of mutations may change, new mechanisms of evolution may turn up, humans ironically by understanding our genome have acquired the ability to manipulate it in intelligent fashion, and so on.
slickrick216 6y ago
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.