News: AAAS 2009 Annual Meeting News
New Research Uncovers Dining Habits of Early Humans
How did our culinary tastes evolve? Recent findings have challenged conventional views of early human diets, said Peter Ungar, a professor of anthropology at University of Arkansas, Fayetteville, who along with colleagues participated in a press briefing 12 February at the AAAS Annual Meeting in Chicago.
In particular, one prevailing view has been that early humans "were like chimpanzees on steroids, eating really hard foods," explains Matthew Sponheimer, associate professor of anthropology, University of Colorado, Boulder.
After analyzing fossilized teeth, however, Ungar concluded that an early human cousin known as the "Nutcracker Man" (Paranthropus boisei), so-named for his powerful choppers, mostly ate the ancient equivalent of gelatin. Now Ungar is proposing that the physical adaptation for chewing hard foods may be triggered by crisis situations, rather than everyday dietary needs. Ungar details some of his most interesting findings in a podcast on Eurekalert!, the global news service managed by AAAS.
"Just because you own a fast sports car doesn't mean you drive 200 miles per hour every day," he explains. "But if you get chased every now and then, the extra power comes in handy." Sponheimer's latest isotopic studies, meanwhile, may call into question the notion that a narrowly specialized diet contributed to the extinction of early hominids.
Writing in the Guardian after a news briefing today, Ian Sample reports that the research connects our modern obesity epidemic to the rapid growth of the human brain and body that occurred over the past 2 million years. He added that roughly one-quarter of the energy spent by humans while resting is used by the brain.
Citing researchers at the press briefing, Sample concluded: "The expansion of the human brain, which coincided with the arrival of the first hunter-gatherer economies, required early humans to bolster their diets by seeking out more energy-rich food."
While chimps and gorillas can survive on leaves and fruits, Richard Alleyne wrote in the Telegraph that humans must eat more calorie-rich foods like meat and nuts.
What does the research about our distant relatives say about our dietary needs today?
"Higher calorie, nutritionally dense diets became necessary to fuel the energy demands of the exceptionally large human brain and help switch from a foraging to 'hunter-gatherer' existence," Alleyne wrote. "But the transition from an extremely active subsistence to a modern, sedentary, lifestyle has created energy imbalances that have played a major role in obesity."
When humans transitioned to an agricultural lifestyle, "our health declined dramatically," Ungar says in the podcast. "The average human stature started dropping. There's evidence of all kinds of malnutrion."
The problem isn't simply that we switched, he said, but that we "greatly decreased the range of foods that we consume.
"The typical American diet is mostly processed flour, fat, and occasionally people throw some tomato sauce on top of it," Ungar said, only half-joking. "The real secret here is a broad-based diet that incorporates a great number of food items to make sure that we get all of the nutrients we need--and none in excess."
Ungar and other speakers will take part in a AAAS Annual Meeting Seminar on "The Evolution of Human Diets," which is scheduled for Friday 13 February, from 8:30 to 11:30 a.m. in the Hyatt Regency Crystal Ballroom B.
In addition to Ungar and Sponheimer, other seminar speakers will be: William Leonard, professor of anthropology, Northwestern University, Evanston, Illinois.; Anne Stone, associate professor, School of Human Evolution and Social Change, Arizona State University, Tempe; and Richard Wrangham, professor of biological anthropology, Harvard University, Cambridge, Massachusetts.
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