Gail McQueenProfessional Home Economist |
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BackWhat did humans evolve to eat?In mid November I had the pleasure of attending the annual Professor Edna W. Park Lecture at the University of Toronto. This year the lecture was entitled "What did humans evolve to eat? Human nutritional health in comparative perspective." It was presented by renowned anthropologist Professor William R. Leonard. Given the present popularity of the paleolithic and other caveman-like diets I came to this lecture with a certain amount of enthusiasm and interest. I was not disappointed. Professor Leonard has studied human populations all over the world, from prehistoric to modern man including present day indigenous agricultural and traditional herding populations. He shared with us some of that research. The lecture began with an introduction to our early ancestors. What really sets us apart from other primates is our brain, which through evolutionary history has been far larger. This increased capacity comes at a cost. Our brain requires 400 kcal/day at rest. Professor Leonard believes much of early human evolution was influenced by the need to fulfill the nutritional requirements of this large brain. He points to some of these evolutionary milestones; the development of tools, the journey out of Africa, the beginnings of agriculture. Throughout history humans have successfully adapted to acquire the necessary amount of food. As numbers grew we see social collaboration and improvements in agriculture. When confronted with food that was less than suitable, humans were able to develop processing methods to compensate. Such processing included cooking, the alkalinization of maize in the Americas, and the detoxification of cassava in Bolivia. Thus, the large brain not only necessitated adaptations. It also facilitated them! So what have we evolved to eat? He concludes that we are truly omnivores. We have an enlarged small intestine like a plant eater but a small colon like a carnivore. We have successfully thrived in almost every ecosystem on earth, consuming a variety of diets, from a very high animal protein diet in the Arctic, to diets in other areas of the world that vary considerably in the amounts and types of animal and plant . Our evolution has not limited us to any one optimum diet. On the contrary we have been successful because we are flexible eaters. We are now seeing obesity in the modern world at all time highs, along with associated health issues like diabetes, hypertension and heart disease. He implies that we may be a victim of our own success. Professor Leonard has developed some very interesting energy intake and expenditure models that suggest that a large part of our present health problems simply are a result of an energy imbalance. It's not that we are eating so much more than our ancestors. It's that we are moving less. We no longer need to strive to fulfill our energy needs. We need to balance our intake and energy expenditure better. Note: The Professor Edna W. Park Lecture was established in the Spring of 1974 by the Household Science Alumni to honour one of it's outstanding members, Professor Edna W. Park, for her notable contribution to the field of Home Economics in Canada. Edna Park was a Professor Emerita of the University of Toronto whose teaching career spanned almost half a century. Gail McQueen P.H.Ec. |
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