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Is the Environment Messing with Gene Expression?

Wishful

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https://newatlas.com/biology/median-artery-forearms-evolution-increasing-prevalence/

The article is about an increase in the prevalence of people retaining a third artery in their arms. This artery is a holdover from our evolutionary past. Normally it grows in the embryo, then disappears well before birth. We have other holdovers, such as tails and reptilian muscles that usually do the same thing. The retention of this third artery has been increasing in frequency over the last 150 years.

The article claims that it's a sign of natural selection. However, as the comments argue, there's no sign of it being selected. Humans don't look at someone and think "Hey, that person has a third artery in their arms. I want to make babies with them!" There's also no indication that this third artery increases the production of babies or the survival of potential parents. Personally, I think the researchers should be embarrassed about claiming that it's a sign of natural selection.

Another comment suggests that this may be a sign that something in our modern lifestyles or environment is affecting the development of embryos, including the 'terminate' sequence for this and other genes. Thus, some modern medical problems might be due to something messing up our embryonic--or even later--development. If ME is proven to be increasing in frequency, this is a possible reason for it.

This could be a new branch of medical science: the study of factors that affect fetal development. Does a food additive affect development of some organ? Does the microbiome? Maybe some gene sequence depends on a certain bacteria carried in human armpits, and modern hygiene has removed that. All sorts of possibilities.
 

Pyrrhus

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The retention of this third artery has been increasing in frequency over the last 150 years.

The article claims that it's a sign of natural selection.
Personally, I think the researchers should be embarrassed about claiming that it's a sign of natural selection.

Ha! Yeah, societal trends over the last 150 years, which generally promote egalitarianism, have tended to push back against natural selection.

The more obvious explanation is the vast improvement in nutrition over the last 150 years, leading to fewer birth defects and lower infant mortality.

But yes, there are lots of other explanations as well...
 

Wishful

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The more obvious explanation is the vast improvement in nutrition over the last 150 years, leading to fewer birth defects and lower infant mortality.

Well, if better nutrition is allowing more holdover genes to be expressed longer, we should be seeing more tails too, which I don't think is happening. Nutrition is a possibility though.

What the study really calls for is geographic analysis. Is this abnormality equal all over the world, or is it higher in areas with something in common? Maybe it's more common among babies raised on canned milk (BHT from the cans), or from mothers in a certain age group.