New research has shown that human beings developed lighter and more easily broken skeletal systems shortly after man became a farmer. Anthropologists and biologists from the Smithsonian Institution’s National Museum of Natural History and colleagues are the first to make the connection between bone strength and farming.
The researchers examined the density of the femur and the head of the femur in Native Americans in the same region of Illinois from between 7,000 and 6,000 years ago. The selection of a limited area presumes equivalent natural conditions and eliminates some variables that might change bone density. The researchers also examined the bone density of the majority of apes and direct ancestors of man that are known to exist. The result indicates that bone density in man decreased when man changed from a hunter-gatherer to a farmer.
The researchers propose two possibilities for the change in bone density. As man became a farmer, he consumed more grains and more dairy products as opposed to the diet of hunter-gathers. A change in diet could produce the change in bone density but not at as rapid a pace as the fossil record indicates.
The change in bone density in modern man was the result of a more sedentary lifestyle. Less dense bones were not necessary for people that did not experience the rigors of daily hunting, walking, and potentially fighting for food. The researchers also note that evidence exists that man could improve the density of his bones by exercising more.
