Actually, there’s a lot of evidence that points to intelligence being a sexually selected trait rather than naturally selected, so in that sense it may actually negatively correlate with survival. In other words, your big brain is the human equivalent of peacock features; it will get you laid but doesn’t do much good when a tiger comes around.

Think of it this way: to sit around doing math problems all day, you have to have the basic necessities for survival dealt with, which shows you’re a good mate within the current environment. Which is all well and good until times change, the going gets tough, and you need to kill something to put food on the table.