Modern day obesity might have evolutionary originsFebruary 13th, 2009 - 4:10 pm ICT by IANS
Washington, Feb 13 (IANS) That craving for a cheeseburger is rooted in the dramatic growth of the human brain and body, resulting from environmental changes two million years ago.
Higher quality, nutritionally dense diets became necessary to fuel the high-energy demands of humans’ exceptionally large brains and for developing the first rudimentary hunting and gathering economy.
But the transition from a subsistence to a modern, sedentary lifestyle has created energy imbalances that have increased rapidly — evolutionarily speaking — in recent years and now play a major role in obesity.
Activity patterns must get every bit as much attention as consumption of unhealthy foods in any attempt to reverse the modern-day permeations of an evolutionary trend that now contributes to obesity worldwide, said William Leonard.
Leonard, who is professor of anthropology at Northwestern University said “while our large-bodied ape relatives — chimps, gorillas and orangutans — can subsist on leaves and fruit, we needed to consume meat and other energy-rich foods to support our metabolic demands.”
Two million years ago shifts in foraging behaviour and dietary quality helped to provide the energy and nutrition to support the rapid evolutionary increases in both the brain and body sizes of our ancestors.
But substantial reductions of intense physical activities for adults living a modern lifestyle in the industrialised world have dramatically lowered the metabolic costs of survival.
“Think about our ancestors,” Leonard said. “Human hunter-gatherers typically move eight miles per day in the search for food. In contrast, we can simply pick up the phone to get a meal delivered to our door.”
The imbalance between energy intake and energy expenditure today, Leonard concludes, is the root cause of obesity in the industrialised world, said a Northwestern release.
Leonard presented his work at the 2009 American Association for the Advancement of Science (AAAS) meeting in Chicago on Friday.