lostonearth35 wrote:
I guess it's because we don't really need them. I heard dodo birds lost their ability to fly because they didn't have natural enemies to flee from (until the humans showed up, anyway).
But then why do we still have an appendix, tonsils or wisdom teeth if all they really do is cause us pain and suffering and we end up having to get them surgically removed? I guess nature is just some kind of a sadist.
The appendix stores gut flora which helps speed up recovery after diarrhea, the tonsils contribute to immune function and wisdom teeth mostly didn't cause problems until recently:
Quote:
...molar impaction was relatively rare prior to the modern era. With the Industrial Revolution, the affliction became ten times more common, owing to the new prevalence of soft, processed foods.
But, broadly speaking, natural selection doesn't select for perfection, it selects for good enough.
The reason we don't have tails is largely down to becoming better adapted for climbing and brachiation. Apes faced selective pressures for more mobile shoulder joints, stiffer backs, higher grip strength and slower, more deliberate movement through branches.
Old world monkeys mostly run along the tops of branches, while apes tend to be much more upright. Once grip strength and limb mobility start to become more important, a tail serves less of a purpose, meaning a tailless state can become fixed, whereas earlier the lack of a tail would be more of a detriment.
Early apes like Proconsul and Ekembo show that grip strength and limb mobility were already traits that were strongly selected for by the time taillessness was fixed, prior to apes starting to develop much wider rib cages and hips compared to monkeys.
Apes aren't the only primate to lose their tails when selected for grip strength. Lorises and bushbabies are each other's closest relatives, with the common ancestor looking much more like a bushbaby. Lorises are vertical clamberers like apes, with high grip strength and no tails, also like apes.
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