Human Heads Getting Larger

Measurements taken of white American skulls over the last 150 years indicate that our skulls have gotten about 8 mm taller, space for about a tennis-ball's worth of brain matter.  Other races have not been measured, but it is likely that the same change is occurring for others as well.

The average skull size for homo species grew steadily until about 30,000 years ago and then plateaued.  Then, around 5,000 - 6,000 years ago, they shrunk a bit - around the same time humans mastered agriculture.  One theory is that food became much easier to acquire, and therefore we didn't need to be quite as smart to survive.

The cause for the recent growth is unknown, but it certainly seems possible that the industrial age has wrought evolutionary changes on our species.