Evolution's natural selection looses it's power after ones child reached maturity. It's now up to our frontal lobe to keep on improving our bodies. With that

Evolution's natural selection looses it's power after ones child reached maturity. It's now up to our frontal lobe to keep on improving our bodies. With that said, it's possible that long life might have negative effect on resource availability which might affect procreation and child rearing, and might find shorter life-span more advantageous to survival of species.