More and more humans are growing an extra artery, showing we're still evolving

https://www.sciencealert.com/more-humans-are-growing-an-extra-artery-in-our-arms-because-we-re-still-evolving

by donatzsky • 5 years ago

71 43 5 years ago

No, it's showing that we maintain the extra artery. There is no reason to believe this is an evolutionary change - there are plenty of hormonal and other environmental factors that could be contributing as well.

crazygringo• 5 years ago

Exactly -- if the rate of change is as high as they state -- from 10% to 30% of people in a little over a century -- it seems it would be essentially impossible for it to be the result of natural selection or genetic change.

As you say, the obvious explanation is hormonal/environmental factors.

gpsx2• 5 years ago

Yes - in order to have a change be that fast it would have to be something that makes those people dramatically better at surviving, like X-men type mutations, or reproducing. I don't think the change of this blood vessel is really turning the tables between survival and death, or making these people that much more successful at reproducing. But with the prevalence of online dating these days, maybe it is a big help by allow people to navigate faster? /s

enkid2• 5 years ago

What do you mean by environmental factors? The environment drives evolution, so changes in the environment would change who survives, which would lead to evolution. If it is an environmental factor that led to selection of individuals having this vein being more likely to propagate, that would still be evolution. This also some very simple scenarios that could lead to such a pressure, like the artery having some minor benefit in reproduction, but a disease we eradicated would disproportionately kill people with the artery.

evancox100• 5 years ago

Agreed, pretty clearly an epigenetic or environmental change, not an evolutionary DNA change.

edgyquant• 5 years ago

I mean, how is that not potentially evolution?

idiotsecant2• 5 years ago

Because non-genetically derived influences are not evolution?

mrkramer• 5 years ago

Evolution is constant since environment we live in is always changing and we need to adapt to it. Extra artery is an anatomical variation[1] because in order to evolve random mutations are happening and whatever works is passed to offspring.

For example this article[2] explains Alan Turing 's Turing pattern[3] and pattern variation of denticles, the toothlike protrusions that cover the skin of sharks.

The article says "Nature tends to invent something once, and then plays variations on that theme." That's true because variation is a way for nature to trial and error certain solutions until good enough solution is found.

[1] https://en.wikipedia.org/wiki/Anatomical_variation

[2] https://nautil.us/issue/68/context/how-alan-turing-deciphere...

[3] https://en.wikipedia.org/wiki/Turing_pattern

ozarkerD• 5 years ago

Given that there’s so much technology available to keep humans alive, will human evolution continue? It seems like it could give rise to a lot of negative traits propagating that would usually mean death before producing offspring a couple hundred years ago.

thunderbird120• 5 years ago

Evolution is the propagation of traits of individuals who survived and reproduced and whose offspring survived and reproduced. In a modern developed country survival is less uncertain but reproduction of healthy individuals is actually more uncertain as can be seen by looking at the birth rates in essentially any developed country. As a result, traits that affect certain behaviors, such as underlying desire to reproduce, are likely under more intense selection pressure now than any traits in all of human history.

thaumasiotes2• 5 years ago

will human evolution continue?

This is a nonsensical question; it isn't possible to have reproduction without evolution.

echelon2• 5 years ago

This is a nonsensical question; it isn't possible to have reproduction without evolution.

It's possible to have reproduction without evolution.

We have monoclonal immunocompromised mice with fixed genomes. We created them.

woleium• 5 years ago

right, so without external pressure we get diversification, making a more resilient pool of phenotypes.

jl6• 5 years ago

In general it's hard to make value judgements about which traits are positive and which are negative. Natural selection cares only for survival advantage of offspring in the immediate environment.

A good example is sickle cell trait, which provides a higher resistance to malaria, but a risk of a variety of other complications. In areas where malaria is a severe threat, the survival advantage of the higher resistance outweighs the other drawbacks. Medical intervention such as administering a malaria vaccine might reduce the threat of malaria such that there would be selection pressure against the sickle cell trait instead of for it.

nradov2• 5 years ago

Evolution will continue. It just won't be heavily influenced by our ability to survive in the natural world.

One evolutionarily change I predict is that certain forms of birth control will become less effective over the next generations. Hormonal birth control isn't 100% effective and there's probably a genetic component to that. So the women for whom birth control doesn't work as well will tend to have more offspring and pass those traits on.

koheripbal• 5 years ago

Obesity as well, since birth control is less effective on women who are very heavy.

WalterBright• 5 years ago

will human evolution continue?

Of course it will. For example, social media has completely changed the way people date and pick partners. This will inevitably change the next generations.

aksss• 5 years ago

This is about a condition called Persistent Median Artery or PMA, and it's a bit of a rabbit hole. Evidently having this condition is associated with increasing your odds or the impact of carpal tunnel syndrome.

PMA can manifest in a few different configurations, like depth to which it extends in the hand, thickness, etc. Here's an interesting read with pictures of dissected forearms showing PMA variants. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6327784/

kafkaIncarnate2• 5 years ago

More and more people are also getting heart attacks. Coincidence? I think not! Evolution is selecting humans out!

dylan6042• 5 years ago

I think human diet is selecting humans out. Nature didn't create food products, humans did. We took food, and created a product. How absolutely mind boggling dumb that just sounds to me. Food doesn't have ingredients; food are ingredients.

bserge• 5 years ago

Only those who can live on a diet of McDonald's and soft drinks will survive!

benkuhn• 5 years ago

I'm not an evolutionary biologist, but it seems to me that the claimed magnitude of the change is wildly implausibly fast from an evolutionary perspective. I'm confused that neither the article, nor the paper it cites, addresses this.

To go from 10% to 30% in ~5 generations, the median-artery-having population would have had to expand by (30/10)^(1/5) = 25% more than the non-median artery population over each generation. It just seems totally implausible that median artery carriers could have that much more offspring.

This makes me pretty suspicious that the paper may be wrong.

rixed3• 5 years ago

You could also suspect that your understanding of evolution is not 100% correct.

Genes do not necessarily propagate in a population because they enhance reproduction. They can have no or very little influence but still propagate by chance. (Similarly, beneficial mutations can disappear from the genetic pool by chance). Lookup "genetic drift".

By the time the environment does change (which can happen as quick or slow as one wants), the lucky genes are already spread in the population and may turn useful or detrimental to the individuals after that environmental change.

Also, genetics is not the only driver for evolution.

sxg• 5 years ago

I really dislike these articles on pop-sci websites. It’s basically just another clickbait news site except it has the word “science” displayed everywhere to give itself slightly more legitimacy.

This artery is just another normal variant. There are tons and tons of normal variants throughout the body including major central arteries (eg aberrant right subclavian, retropharyngeal carotids). The changing prevalence is likely more an artifact of data collecting than anything meaningful, just like most of the articles on these sites that gain any traction.

jacquesm• 5 years ago

Of course we are still evolving. It's just that the selection pressures applied are different now than they were in the past, and this doesn't look like something subject to selection pressure so I doubt it is an example of evolution in progress.

senectus1• 5 years ago

My dentist claims that the fact I was born without wisdom teeth is a sign of evolution as well.

Apparently its increasingly more common.

Happy to claim i'm more highly evolved than others :-P

(yes I know evolution is small gradual changes not some superpower. its a joke people)

justsomeuser• 5 years ago

My understanding is that cell based life never stops evolving - it is a constant feedback loop with the environment to build organic tools to extract resources from the environment.

It always makes me laugh when people have the concept that we humans are completely separate things from the species in the animal kingdom.

More and more humans are growing an extra artery, showing we're still evolving

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