I tend to think like this too. If the change is small/easy evolution probably tried it already. A standard guess for a "downside" would be increased energy expe

I tend to think like this too. If the change is small/easy evolution probably tried it already. A standard guess for a "downside" would be increased energy expenditure (but only a guess). Also, Klotho seems to decline with age, and old people are not as well optimized by evolution, since they don't procreate (directly).