The human form is changing. People around the world are getting bigger and parts of their bodies are shifting in shape. In this shape-shifting world, the U.S. is leading the pack in growing bigger, taller heads, though no one knows exactly why.
U.S. skulls have become larger, taller and narrower as seen from the front and faces have become significantly narrower and higher.
“The varieties of changes that have swept American life make determining an exact cause an endlessly complicated proposition,” says researcher Lee Jantz, coordinator of University of Tennessee’s Forensic Anthropology Center. “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 8 millimeters (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 7 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 increased only about 2 percent. Also, skull height has continued to change, whereas the overall human height has recently slowed or stopped.
The research assessed only Americans of European ancestry because they provided the largest sample sizes to work with. Changes in skeletal structure are taking place in many parts of the world, but tend to be less studied. Research has uncovered shifts in skull shape in Europe, though it is not as dramatic as seen in the U.S.