Anthropologists Find Heads of White Americans Are Getting Bigger

Posted on May 30, 2012

White Americans' heads are getting bigger say forensic anthropologists at the University of Tennessee, Knoxville. The research only assessed Americans of European ancestry because they provided the largest sample sizes to work with. The researchers examined 1,500 skulls dating back to the mid-1800s through the mid-1980s. They noticed U.S. skulls have become larger, taller and narrower as seen from the front and faces have become significantly narrower and higher. The researchers cannot pinpoint an exact reason why American head shapes are changing.

The researchers found that the average height from the base to the top of the skull in men has increased by eight 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 seven millimeters and 180 cubic centimeters. Skull height has increased 6.8% since the late 1800s, while body height has increased 5.6% and femur length has only increased about 2%. Skull-height has continued to change whereas the overall heightening has recently slowed or stopped.

Lee Jantz, coordinator of UT's Forensic Anthropology Center (FAC), says, "The varieties of changes that have swept American life make determining an exact cause an endlessly complicated proposition. 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 scientists noted changes that illustrate our population is maturing sooner. This is reflected in the earlier closing of a separation in the bone structure of the skull called the spheno-occipital synchondrosis. In the past the structure was thought to fuse at about age twenty. The researchers found the bone is fusing much earlier today - around 14 for girls and 16 for boys. America's obesity epidemic could aso affect skeletal shape, but its precise effects are unclear.

Richard Jantz said changes in skeletal structure are also taking place in many parts of the world, but tend to be less studied. He said research has uncovered shifts in skull shape in Europe though it is not as dramatic as seen in the U.S.

The research was conducted by Lee Jantz, coordinator of UT's Forensic Anthropology Center (FAC); Richard Jantz, professor emeritus and former director of the FAC; and Joanne Devlin, adjunct assistant professor. The findings were presented on April 14 in Portland, Ore. at the annual meeting of the American Association of Physical Anthropologists.