Humans have been hunting for sex-based differences in the brain dating back to at least ancient Greece. Yet a scientist observing a female and male brain in a lab can’t tell them apart. "I'm not aware of any measure you can make of the human brain where the male and female distributions don't overlap," Dr. Armin Raznahan told Live Science. That said, the question of how male and female brains differ may still matter. @LiveScience has more: