WHY WE’RE NOT SMARTER: Big brains vs. strong immunity: Genes hint at evolutionary tug of war. Plus, the value of miscegenation:

The genetic record indicates that the human species passed through a series of “bottlenecks” in prehistoric times that reduced population diversity to perilously low levels. That’s where interbreeding with Neanderthals could have played a part. “One way that modern humans replenished the genetic diversity lost in populations was through the selection of new variants … another, and possibly more effective, mechanism was to acquire old variants by mating with archaic humans,” Parham and Moffett write.

What’s Cro-Magnon for “Hey, baby, let’s replenish some genetic diversity?”