[Zababa]

> Given how much of humanity's existence has been staving off starvation and famine, any improvements would be heavily selected for, and would quickly spread.

If that was true, shouldn't we have evolved to hibernate at some point?

> You can't reproduce if you die from lack of nutrients.

You also can't reproduce if you can't run fast when a wolf is hunting you. Those muscles are going to take some energy even while not running away from a wolf. I think you're trying to reduce evolution and reproduction to a single variable, which is a mistake.