Guppies with experimentally shrunken brains produced more offspring than guppies bred for larger noggins, confirming a long suspected tradeoff of bigger brains.
A bevy of genes known to be active during human fetal and infant development first appeared at the same time that the prefrontal cortex—the area of the brain associated with human intelligence and personality—took shape in primates.
Unlike human brains, chimpanzee brains don’t get smaller as they age, suggesting that pronounced neurological decline is a uniquely human byproduct of our oversized brains and extreme longevity.