No, no, no, absolutely not, no, it doesn't. No. A feature can maintain itself in a population for a number of reasons:
- it's neutral or not detrimental enough to drive affected individuals to extinction (ie, to get them killed before they have a chance to reproduce)
- it's linked to some other trait that provides actual benefits
- it's so recent it didn't leave time to be selected against
- or, yes, it actually has some adaptive function.
But just because a feature is found does NOT "prove" anything in and of itself.
> Living in small bands of hunter-gatherers, our ancestors were primarily concerned with their social standing, and with making sure that they weren’t the ones risking their lives on the hunt while others loafed around in the cave. There was little advantage in reasoning clearly, while much was to be gained from winning arguments.
Excuse me, what?? There's little advantage in reasoning clearly while hunting prey and making tools and building traps to catch huge mean animals that can and will kill you if you do anything wrong?
And there's much to be gained from "winning arguments" in a cave, while pondering about one's social standing?? Come on.
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I suggest a more simple and straightforward explanation for the limitations of "reason": our brain is, in fact, write only.
We usually don't notice it because it also has a huge capacity and so we can always write more, it never gets full.
But to one given named item corresponds a unique value, that cannot be overwritten.
If you want to store a new value you have to create a new name to store it with.
To "overwrite" something you can create lookup tables of sort, that tell you that the old value is in fact "wrong" and that said item should be associated with another, newer item. But this is costly, and so is avoided whenever possible (because the first rule of life is to be lazy, ie to conserve resources).