- Survey of 1500 skulls from mid-1800s to 1980s
- Volume of skulls has risen by size of tennis ball
- Faces are becoming longer and narrower
- Are Americans evolving? Or are lifestyle factors to blame
- Study of white remains as largest sample size available
The heads of Americans are changing – and rapidly – skulls are getting bigger and faces are getting longer and narrower.
Within just 150 years, American heads have grown in volume by roughly the volume of a tennis ball.
The survey of 1500 skulls compared skulls from the mid-1800s to skulls from the Eighties – and the shape is definitely changing.
Are Americans evolving? The researchers don’t know – the changing head shapes (found in samples of white Americans) could also be due to better nutrition or racial mixing.
‘The varieties of changes that have swept American life make determining an exact cause an endlessly complicated proposition,’ said Lee Jantz.
‘It likely results from modified growth patterns because of better nutrition, lower infant and maternal mortality, less physical work, and a breakdown of former ethnic barriers to marriage. Which of these is paramount we do not know.’
The researchers found that the average height from the base to the top of the skull in men has increased by 0.3 inches.
The skull size has grown by 200 cubic centimeters, a space equivalent to a tennis ball.
In women, the corresponding increases are seven millimeters and 180 cubic centimeters.
Skull height has increased 6.8 percent since the late 1800s, while body height has increased 5.6 percent and femur length has only increased about 2 percent. Also, skull-height has continued to change whereas the overall heightening has recently slowed or stopped.