by Timothy M. Ryan and Colin N. Shaw
Published December 22nd, 2014
Evolutionary biologists have recently discovered that the human skeleton has become much lighter and more fragile since the switch from hunting-gathering to farming. According to new research 7000 years ago the human bone was almost as strong as the modern orangutan; 6000 years later bone mass had decreased by about 20%. Researchers have been hypothesizing on why this shift occurred. It could possibly be due to a new diet, as with the shift to farming came a less diverse choice of foods. After running more experiments with the fossils this theory was eventually decided against as well as the theory that there was a separate change in body size. Rather they think that the change is due to the change in amount of exercise, which would mirror research suggesting that bone health is more dependent on exercise than a calcium rich diet. On that note the future of bone health and human fitness looks even more grim. “There's seven million years of hominid evolution geared towards action and physical activity for survival, but it's only in the last say 50 to 100 years that we've been so sedentary -- dangerously so," says Dr Colin Shaw, an evolutionary biologist at the University of Cambridge. And he’s right; these days TVs, phones, and computers, all derail from our once very active lifestyle. Next, Shaw’s research team is looking to find correlations between the agility of marathon runners and the structure of their bones.
This article exemplifies the process of natural selection and evolution, and is very relevant to our evolution unit. As learned in class, genetic changes are largely affected by differences in the environment. One of these genetic changes was a decrease in bone mass.
Do you know if the amount of bone mass in a human being reliant on a gene, or could someone today gain the amount of bone mass that people had 7000 years ago just with exercise and consuming calcium?
ReplyDeleteWhile there is definitely a genetic component to the amount of bone mass a person has, environment and personal exercise also play a very important role. Hypothetically, yes, a very athletic person of today's bone mass could, with the right influx of calcium, acquire the amount of bone mass that people had 7000 years ago. However it would be very difficult to achieve and very unlikely for even the most rigorous athletes to manage.
DeleteWhy were the two earlier hypotheses of a change in diet, or a separate change in body size changing the strength of human bones debunked?
ReplyDeleteA change in diet is unlikely. When humans made the switch from forager to farmer there was a drastic cultural change- they stopped eating various meats and plants and began living off of a monoculture. However the skeletons and fossils tested from this time did were not significantly changed. Rather, the change occurred a few years after the shift. A separate change in body size is also unlikely; the modern day human is not constrained by their anatomy and can hypothetically be as strong as an orangutan. The decrease in bone mass is not due to the inability to possess denser, stronger, bones, but rather the inability to maintain, with physical exertion, these dense strong bones.
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