Forearm artery reveals human evolution continues? • Hacker News Board

Re: Forearm artery reveals human evolution continues?

#21

Post by learc83 » Sat, Oct 10, 2020, 7:47 PM UTC

Retric wrote: post #14

carbocation wrote: post #10

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…

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.

> #2 killer in the US it’s likely for the circulatory system to be undergoing rapid change.

Primarily killing people past reproductive age though.

Re: Forearm artery reveals human evolution continues?

#22

Post by oh_sigh » Sat, Oct 10, 2020, 7:49 PM UTC

fs_tab wrote: post #12

iheartblocks wrote: post #2

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

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 evol…

No need to request: https://scihubtw.tw/10.1111/joa.13224

Re: Forearm artery reveals human evolution continues?

#23

Post by HNAwayGone » Sat, Oct 10, 2020, 7:52 PM UTC

learc83 wrote: post #21

Retric wrote: post #14

Earlier quoted context omitted.

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.

> #2 killer in the US it’s likely for the circulatory system to be undergoing rapid change. Primarily killing people past reproductive age though.

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.

Re: Forearm artery reveals human evolution continues?

#24

Post by rthomas6 » Sat, Oct 10, 2020, 7:53 PM UTC

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.

Re: Forearm artery reveals human evolution continues?

#25

Post by learc83 » Sat, Oct 10, 2020, 7:54 PM UTC

fleischhauf wrote: post #9

dghughes wrote: post #4

Earlier quoted context omitted.

>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?

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…

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.

Re: Forearm artery reveals human evolution continues?

#26

Post by [deleted] » Sat, Oct 10, 2020, 7:55 PM UTC

learc83 wrote: post #21

Retric wrote: post #14

Earlier quoted context omitted.

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.

> #2 killer in the US it’s likely for the circulatory system to be undergoing rapid change. Primarily killing people past reproductive age though.

[deleted]

Re: Forearm artery reveals human evolution continues?

#27

Post by heeen2 » Sat, Oct 10, 2020, 7:58 PM UTC

iheartblocks wrote: post #2

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

There doesn't need to be selection pressure for a mutation to spread, it just needs to be no disadvantage to develop it

Re: Forearm artery reveals human evolution continues?

#28

Post by mci » Sat, Oct 10, 2020, 8:04 PM UTC

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".

Re: Forearm artery reveals human evolution continues?

#29

Post by leephillips » Sat, Oct 10, 2020, 8:08 PM UTC

Someone wrote: post #13

dghughes wrote: post #4

Earlier quoted context omitted.

>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?

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…

More stamina when composing romantic emails → greater chance of reproduction.

Re: Forearm artery reveals human evolution continues?

#30

Post by learc83 » Sat, Oct 10, 2020, 8:09 PM UTC

HNAwayGone wrote: post #23

learc83 wrote: post #21

Earlier quoted context omitted.

> #2 killer in the US it’s likely for the circulatory system to be undergoing rapid change. Primarily killing people past reproductive age though.

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.

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.