Culture skews human evolution | Harvard Gazette
news.harvard.edu/gazette/story/2009/.../culture-skews-human-evolution/Mar 12, 2009 - Lieberman expounds on 'dysevolution' | The rise of agriculture 10000 years ago meant the end of the hunter-gatherer lifestyle for which human ...
Culture skews human evolution
Lieberman expounds on ‘dysevolution’
The rise of agriculture 10,000 years ago meant the end of the hunter-gatherer lifestyle for which human beings had been optimized by millions of years of evolution and the beginning of an era where culture encourages habits unhealthy for us and for the world around, with uncertain evolutionary outcomes.
“Our bodies are not that well-designed for the world we have created,” said anthropology professor Daniel Lieberman.
Lieberman spoke Thursday (March 5) in the third of the Harvard Museum of Natural History’s (HMNH) “Evolution Matters” lecture series. His talk, called “Survival of the Fleetest, Smartest or Fattest?” reviewed the evolutionary trends that led to modern humans and discussed the cultural reasons for some of today’s major health ills, such as obesity and diabetes.
Lieberman, who was introduced by HMNH Executive Director Elisabeth Werby, said the four most significant events in human history were our separation from apes; the evolutionary development of the genus Homo, shared by modern humans, Neanderthals, and Homo erectus; and the separation of our species, Homo sapiens, from our common ancestor with other Homo species.
The final event, Lieberman said, was a cultural one, not an evolutionary one. The beginnings of agriculture 10,000 years ago created lasting change that led to modern society and our modern way of life.
Farming culture allowed human women to give birth more frequently, spurring population growth. It also led to the spread of disease, as humans were in close contact with a variety of animal species, such as chickens, pigs, and cows, providing an environment in which animal viruses could pass into humans. It also led to the protection of people who physically might not survive in a hunter-gatherer society, and the rise of conditions and ailments such as myopia and diabetes.
The result, Lieberman said, is a cultural buffering of evolution’s harsh rule of “survival of the fittest” that may be leading to the “dysevolution” of Homo sapiens.
Though scientific opinion varies on whether evolution is still acting on humans, Lieberman said it probably is, pointing to relatively recent developments of lactose tolerance in adults — allowing them to consume dairy products long after weaning — and of pale skins in those from northern climates.
To understand the roots of “dysevolution,” one must understand where humans came from, Lieberman said. Descended from a common ancestor with chimpanzees between 6 million and 8 million years ago, early primitive humans like Sahelanthropus and Ardipithecus were very chimplike but walked upright. Lieberman traced this adaptation to climate change, namely a planetary cooling that transformed large tracts of thick jungle to open woodlands where walking would be a more efficient form of locomotion than either the climbing or knuckle-walking at which chimps excel.
The next change, Lieberman said, was driven by an additional cooling, which led to further thinning of the forests and the rise of savannah. From these changes arose the genus Homo between 2 million and 3 million years ago. Early human ancestors evolved different adaptations to survive on the savannah, with an Australopithecus species becoming adapted to large amounts of low-quality food, as evidenced by their large teeth.
The Homo genus evolved a different way of life, adapting for high-quality, high-energy foods, and becoming good at running in the heat of the day to engage in “persistence hunting” to run down exhausted prey species.
The first Homo sapiens appeared about 200,000 years ago and may have evolved from Homo heidelbergensis, Lieberman said, and continued to invent new tools and technology, spreading out of Africa to Europe, Asia, and other parts of the world. We were smart, inventive, highly mobile endurance athletes who cooked our food to get more energy from it. We were also relatively fast breeders when compared with other apes, with a baby every three years.
These evolutionary solutions were successful, Lieberman said, but energy intensive. The problem today, Lieberman said, is that humanity’s “gas guzzling” strategies, which enabled them to survive on the African savannah and expand around the world, aren’t always helpful in an era with ready fast food, sugar-rich snacks, and steadily decreasing demand for physical exertion.
“Obviously, they stood us in good stead until the very recent past,” Lieberman said.
Since we can’t will ourselves to evolve so that we don’t crave high-energy foods, Lieberman said we should instead encourage our inner hunter-gatherer by requiring more physical activity of our kids in schools, raising gasoline taxes to discourage driving, outlawing fast food, and restricting access to elevators, escalators, and moving sidewalks to force us to walk more.
“We need to think more like Darwin and act more like hunter-gatherers,” Lieberman said.Dysevolution: How changing habits are making humans sick ...
scienceline.org/.../dysevolution-how-changing-habits-are-making-human...Dec 9, 2013 - Humans now have a better chance to live longer, healthier lives. ... you to cope with the condition, thus contributing to cycle of dysevolution.
Dysevolution: How changing habits are making humans sick
A new book proposes that cultural changes in the last few centuries have propogated non-infectious diseases that our ancestors didn't face
Human evolution through the ages [Image Credit: Flickr : Gerardo Almaraz]What do diabetes, nearsightedness and flat feet have in common?They weren’t such a problem until a few hundred years ago, when cultural changes began to outpace human evolution.While connecting evolution to myopia might seem like a stretch, Daniel Lieberman, an evolutionary biologist who teaches at Harvard, did just that, and convincingly too, at a recent talk at the American Museum of Natural History in New York. Studying evolution can actually answer a lot of questions you never thought you would ask, like why pregnant women don’t tip over, a study that won Lieberman a sarcastic Ig Nobel prize in 2009. A few years back Lieberman had gained worldwide recognition, when his research on the science of barefoot running was published as the cover story in Nature in 2010. In his recently published book “The Story of the Human Body: Evolution, Health and Disease,” Lieberman has tried to present the story of human evolution and answer a simple question — why is it relevant now?
“Natural selection is still going on today. Our Stone Age bodies are adjusting to being in the Space Age,” Lieberman says. “The difference is that now, an additional selection criterion of human culture is added.”
When seen through a macroscopic lens of the history of human life on earth, this truly is a good time to live. Numerous studies echo the same findings; the average lifespan is longer, infant mortality is down. Humans now have a better chance to live longer, healthier lives.
However, deaths due to non-infectious diseases such as cancer, heart diseases and diabetes are on a rise. Furthermore, people today also suffer from a higher incidence of lower back pain, dental cavities, myopia and mental health issues than ever before in the history of mankind. Almost all of these are examples of mismatched diseases, those that occur simply because our body has not evolved for modern times.
So, why are we seeing these mismatched diseases now? Lieberman suggests that “dysevolution,” a vicious circle of treating the symptoms instead of the causes of these diseases, is to blame. Like in case of diabetes, the genetic anomalies that could increase the risk for developing it were always present in our DNA, however, changes such as increased consumption of processed foods and decreased physical activity have tipped the balance.
In the case of nearsightedness, changes such as an increase in reading habits or time spent indoors, have occurred slowly over the last few millennia and are thus hard to perceive, a characteristic of dysevolution. Most of all, these changes go unnoticed in the evolutionary scheme of things, since it has no effect on the reproductive success of an individual. Being myopic or diabetic hasn’t stopped people from having children.
Finally, the need for comfort has also spurred the rise of some mismatched diseases. Barefoot long-distance runners are less likely to suffer from flat feet than non-runners who spend their entire day in shoes. While shoes might make walking or running more comfortable, they have also made flat feet more common, with 30 percent of Americans suffering from it. And while orthotics don’t cure flat feet, they allow you to cope with the condition, thus contributing to cycle of dysevolution.
Put simply, humans have become quite lazy. Evolution drives humans to look for ways to reduce energy consumption in any activity, which means reduced physical activity and an increased vulnerability to problems that were not encountered a few centuries ago.
Although no one expects humans to stop adopting newer technologies, we could start adopting a healthier lifestyle. “Evolution still matters,” Lieberman says. “It is giving us clues or a path to how we can make the world a better place to live. How different would it be to encourage a child to indulge in increased physical activity, from making him use the seat belt or go to school?”The Story of the Human Body - Harvard Magazine
harvardmagazine.com/2013/10/daniel-lieberman-story-human-bodyOct 1, 2013 - Such instances of what Lieberman termed dysevolution occur when old genes ... Moreover, he continued, education promoting healthy lifestyle ...
Dysevolution-Culture skews human evolution
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