Natural selection has worked pretty well so far. But we, as humans, have a long way to go. The problems with our current form from an efficiency of procreation point of view.

• Men have nipples.
• People have body hair.
• People willingly ingest poisons and drugs.
• We still have the sensation that we're falling out of a tree when we sleep.
• Women are sometimes attracted to women and men are sometimes attracted to men (not that being happy is an issue...it's just not particularly conducive to procreation)