Now, I thought that evolutionary theory was such that a trait that was beneficial would always overpower, or at least remain neutral to, those traits that were detrimental, or otherwise of negligible benefit. So, even after 3 million years, one might expect that a trait for more powerful shoulders, would be more of a survival imperative than proportionally weaker ones. In point of fact, there are many characteristics of early hominid development that would increase survivability over what the human race has inherited.
Apparently he didn't understand the point and ignored me. However, let me expand on it a bit ~ humans have finger nails. The hardness is controlled by genes. About half have hard nails. The other half have soft nails.
It's been that way for hundreds of thousands of years, and probably even millions of years ~ all the way back to the first dude to have fingernails,
Evolutionary theory always said this about that ~ the fingernail type most advantageous to the survival of the species is the type each individual should have.
In the case of important features ~ to wit: fingernails ~ that have 2 variations, and which persist through geologic time ~ the traditionalists would say "see, neither type has survival advantage so both survive". Yet, we can look back up the line to the forebears and some of them have claws ~ well, actually, at some point going back they all had claws, and all claws are hard ~ that's because claws need to be hard. Fingernails that replaced them obviously had more survival advantage so presumably they started off hard as well ~ then what? Well, another type with no clear advantage we can see, the soft ones, came into existence, and now we have some people with hard and some people with soft fingernails.
By now you've probably gotten to the question ~ how is it soft fingernails have an advantage over claws? Your friendly neighborhood bears would probably like to know that answer as well ~ did you know they can open doors using the knobs and levers? Their mothers teach them now to do that. They open your door; go in; raid your refrigerator; and close it.
They'll be back!
Bears have hard claws and can gut you in a NY sec. They can peel oranges if you let them.
So, why nails? Why soft nails?