Human Heads Are Shrinking

There’s no correlation between brain size and intelligence, and if anything, brains today have gotten smaller since the days of our Pleistocene ancestors.  That’s the gist of a report on ABC News Australia based on research at the Queensland Institute of Medical Research: “The genes that are thought to have helped humans evolve big brains don’t appear to play any role in how intelligent we are, according to a DNA study.”

Paleoanthropologists for decades – yea verily, for over a century – have made brain size the gold standard of evolutionary progress and fitness in humans.  Haeckel and Broca and other early researchers used brain size and head shape to rank humans on intelligence scales, promoting ugly racist eugenics programs.  Cranial capacity is still the primary metric for ranking supposed ancestors with modern man; Carl Sagan spoke glibly about evolution producing upright-walking apes with bigger brains, able to use tools, fire and language, on the upward march to modernity.  This find undercuts all of that.  It weighs in also on position of Homo floresiensis in the family tree.  Without brain size as a measure of evolutionary fitness, what else will the Leakeys and Johansons and Whites of the world do now?
    Bigger is not always better.  Most of us would rather have a more compact cell phone or iPod with more features and memory.  Don’t let simplistic assumptions lead your logic astray.