Modern human weight is heavier than their ancestors who survived by hunting and gathering various other needs. But in terms of bone mass, modern humans are lighter than their predecessors. An international research team knows the answer, namely agricultural and sedentary lifestyle.
Because humans develop agriculture and transformed into a more relaxed lifestyle, starting about 12 thousand years ago, people no longer spend most of their time with walking, running or carrying something to get food. In fact, such activity could make the bones grow stronger.
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| Cross-sections of an Upper Paleolithic (L) and Early Medieval (R) thigh bone, showing the change in bone shape and reduction in strength in the later individual. (Picture from: http://bit.ly/1emaJQX) |
The researchers analyzed samples of arm and leg bones of hundreds of people who live in a period of 33 thousand years ago in Europe. They found that their bone weakening gradually as people's lives are increasingly relying on agriculture, and that the move to the city, changing diet and the other lifestyle changes with small effect.
By comparing the thigh and arm bones - are not affected by the habits of walking and running - from various museum collections, researchers can ensure that the changes that occur because of decreased mobility.
In the article in the Proceedings of the National Academy of Sciences, the researchers say, the foot bone strength decreased between the Mesolithic era, 10 thousand years ago, and the period of the Roman Empire, which began about 2,500 years ago. Arm bone strength remains the same.
More lighter bones make modern humans more susceptible to osteoporosis, at high risk of lead fractures. Researchers say weight training can prevent bone shrinkage, and could help people develop more a Paleolithic-style skeleton. *** [EKA | FROM VARIOUS SOURCES | VOA NEWS]
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