The use of reason and technology. Using them, there seems no boundaries to the range of environments we can adapt. Good and bad mutations (if not fatal) are being overriden by medication or technology. Natural selection works no longer on humans at the level of species, yet random genome mutations will continue at a known rate and humans will continue to evolve.
Reason and technology are the result of NS. We just appear to be the best NS has produced so far on this planet. We have begun to take a certain amount of control over NS... perhaps we could call it ES engineered selection. NS is not defunct, it just works much slower than ES