Harvard professor shares insights on human evolution and dysevolution
Daniel Lieberman


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9:42 a.m., May 19, 2010----Why does the human body look the way it does? This question is the driving force behind the work of Dan Lieberman, professor and chair of the Department of Human Evolutionary Biology at Harvard University.

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Lieberman believes the question is important to tackle from an evolutionary perspective because the evolutionary bases of human anatomy and physiology provide insights into how we can prevent many of the illnesses and injuries that plague modern humans.

“Our 21st-century lives are not always healthy for our Paleolithic bodies,” he said in a lecture at the University of Delaware on Friday, May 14, attended by some 150 students, faculty, and staff.

Lieberman quoted Russian geneticist and evolutionary biologist Theodosius Dobzhansk in saying, “Nothing in biology makes sense except in the light of evolution.”

“To prevent and/or treat problems like osteoporosis, cancer, and diabetes,” he added, “we need to understand their causes. The best medicine is preventive medicine.”

Lieberman reviewed key events in human evolution that made humans remarkable endurance athletes and adapted us for a hunter-gatherer way of life. He then talked about how the relatively recent advent of cultivated agriculture and industrialization have had negative effects on human health.

“We no longer have to do physical work because of the profound ways in which the world has changed,” said. “Our bodies are not well designed for the world we've created. Most humans today are not living biologically normal lives.”

Lieberman cited a host of problems -- from liver disease, asthma, heart disease, and osteoporosis to gout, flat feet, and impacted teeth -- that he says have been treated symptomatically but should instead be addressed using an evolutionary approach.

“We need to ask what are the ultimate causes of disease, not just the proximate causes,” he said.

In a process Lieberman calls dysevolution, we have come to rely on cultural buffers, such as diet pills to treat obesity, orthotics to alleviate fallen arches, and drugs to lower cholesterol and blood sugar levels.

Instead, we need to recreate some of the conditions under which our earlier forbears lived, such as getting more exercise and eating less-processed food.

But Lieberman pointed out, many people who suddenly decide to become more active suffer from injuries.

Again, we need to go back to basics. Modern running shoes, he said, have changed our gait and induced many of these injuries.

His answer? Barefoot running, or at least the use of minimal footwear that more closely mimics barefoot running.

“This may sound like a fad,” he said, “but from an evolutionary viewpoint, running in shoes is a fad.”

Lieberman's talk was part of the University of Delaware's Biomechanics and Movement Science Seminar Series

Article by Diane Kukich