And so, after discussing hunter-gatherers and the advent of agriculture, he takes us to the Industrial Revolution and a world that we have engineered to be substantially different from the one that engineered our bodies. The discussion of human evolution takes Lieberman to the case he wants to make about our bodies in the modern world. “The Story of the Human Body: Evolution, Health, and Disease” by Daniel E. Lieberman is particularly good at drawing the connections between the different body systems: “Altogether, without lots of fat, human brains could not be so big, hunter-gatherer mothers would be less able to provide enough high-quality milk to nourish their big-brained offspring, and we would have less endurance.” And of course, from an evolutionary perspective, it all comes back to reproductive success - that is, to the likelihood of creating genetic progeny. To understand our evolutionary diet, you have to look at jaws and teeth, but also at energy metabolism and the different kinds of body fat. Lieberman’s discussion of humans’ upright stance and its consequences - for everything from running and hunting to reproduction and spinal vulnerabilities - integrates structure and function, describing the kinds of tradeoffs and constraints that arise with evolutionary pressure and anatomic change. The excitement of reasoning from evolutionary biology involves paying careful attention to structure and anatomy, physiology and function. The first half of the book discusses human evolution, teasing out current evolutionary thought on such issues as our bipedal stance, our large brains, our dietary habits and our ability to store excess energy in the form of fat. We enjoy rest and relaxation, but our bodies are still those of endurance athletes evolved to walk many miles a day, often run, as well as dig, climb, and carry.” We evolved to run barefoot, he argues we evolved to squat, not to sit in chairs. “Like it or not, we are slightly fat, furless, bipedal primates who crave sugar, salt, fat, and starch,” he writes, “but we are still adapted to eating a diverse diet of fibrous fruits and vegetables, nuts, seeds, tubers, and lean meat. His argument is that many of the health problems we battle have arisen out of a kind of evolutionary mismatch, with our bodies shaped by selective pressures that no longer govern whether we live or die - or reproduce. Lieberman, chairman of the Harvard Department of Human Evolutionary Biology, discusses the impact of natural selection and the dynamics of evolution over all those millennia on the bodies we inhabit. In “The Story of the Human Body,” Daniel E. And some evolutionary explanations that seemed dubious then now seem just silly - I am thinking of one that I dimly recall on the evolutionary advantages of joining a sorority to improve your reproductive fitness.īut it was an exciting time to study evolutionary biology, and it certainly left me with a sense of the intellectual challenge of considering how the long time frame of human evolutionary change might or might not explain modern human patterns and problems. There were battles over notions that seemed radical back then but are now widely accepted - for example, that many aspects of behavior, personality and temperament are strongly affected by genetic tendencies. Wilson published “Sociobiology: The New Synthesis,” and controversial ideas about health, biology and behavior were fought out in some of my college biology classes. I was an undergraduate in 1975, when E.O.
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