American Heads Getting Bigger
New skull space could accommodate a tennis ball's worth of brain.

big headed babies

 Generation by generation, human heads may be growing 
Photograph by Paul Damien, 
National Geographic Dave Mosher for National Geographic News Published June 6, 2012 

Modern life may be going to your head. It's not clear why—medicine? cars? supermarkets?—but the skulls of Americans have become slightly taller and roomier, according to new forensic research. It may not sound like much, but the growth translates to roughly a tennis ball's worth of new brain room.

Ups and Downs of Evolution beginning with the dawn of the first Homo species, human skulls evolved to be increasingly bigger. An inch? That'd be huge," said Sparks."