More and more humans are growing an extra artery, showing we're still evolving
sciencealert.com
sciencealert.com
As you say, the obvious explanation is hormonal/environmental factors.
That can still be considered evolution even if it doesn't provide an obvious benefit.
Better at reproducing. Death after reproduction has much less effect on evolution than death before reproduction.
It is unfortunate that it is so often misstated (I am guessing you already know the difference, but I want to clarify it for those who are not so aware). As an aside, I think the article is complete and utter bollocks.
The change in expression over time and participant count the study highlights is not compatible with a natural selection driven evolution.
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.
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.
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.
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.
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.
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.
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...
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/
It always makes me laugh when people have the concept that we humans are completely separate things from the species in the animal kingdom.
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)
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.