There are many aspects how biology can make "better" humans - faster, stronger, more resilient, etc, but they are not evolutionary useful because they cost extr

There are many aspects how biology can make "better" humans - faster, stronger, more resilient, etc, but they are not evolutionary useful because they cost extra calories and apparently are not worth the cost in a calorie restricted environment. Our bodies have been optimized to have as little of the "good stuff" as possible to conserve calories. We have mechanisms that will prevent building more muscle unless it's really necessary (as shown by exercise) and we have spare food - but it does not have to be this way, e.g. gorillas don't have to exercise to develop their huge muscles, it's just as our bodies (unlike theirs) is heavily optimized in favor of "cheaping out on features" to be more resistant to starvation. IMHO that also fully 'explains away' the issue of "why aren't we already more intelligent". Brains are excessive consumers of energy compared to other organs, so extra brain mass costs calories. At a certain point (which seems to be our current brains) being a bit smarter does not allow a hunter-gatherer to harvest much more calories per day in the seasons/crisis events where food sources are scarce (which are the only times that matter for evolution), so the brain increase stops there, just to save calories. Improvements that are 'zero cost' (i.e. brain structure changes which give more intelligence for the same calorie expenditure) are welcome, but the trivial way of getting more 'processing power' through larger brains is aggressively selected against. And all this calorie saving apparently was worthwhile - e.g. neanderthals were stronger and had larger brains than homo sapiens , but we were a bit more efficient, so we are here and they are not.