The Evolution of Obesity
Publication Year: 2009
Published by: The Johns Hopkins University Press
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Title Page, Copyright
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Humanity is changing in size and shape. There has been a remarkable upsurge in the number of people considered overweight or obese. This change has occurred far too fast to represent population-level genetic change, but there must be biological, and thus genetic, factors involved with the obesity epidemic. Not all people are becoming fat. How can we ...
Introduction: Human Biology, Evolution, and Obesity
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Daniel Lambert was born in Leicester, England, on March 13, 1770. During his relatively short life (he died at the age of 39), he became moderately famous. He met the king of England and other noble-men. People paid money to see him (Bondeson, 2000). He is still relatively famous today. There are exhibits of his clothes and other personal effects in museums in both Leicester where he was born and Stamford where he ...
1 Humanity on the Fat Track
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Humanity is getting fat. Not everyone, but many of us in every quarter of the globe: men and women, young and old, rich and poor, from every race and ethnicity. There is a worldwide obesity epidemic What is amazing, and frightening, is how quickly this change in hu -man body weight is occurring. Within a few generations the bell curve of human weight distribution has shifted and skewed toward greater weight. ...
2 Our Early Ancestors
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Human beings (genus Homo) have changed considerably since the time when our ancestors were the same as those of the chimpan-zee. Of course we retain many features from that time as well. We have more in common with the great apes, especially the chimpanzee and bonobo (genus Pan), than we do with other mammals. However, our lin-eage has been separate from theirs for approximately 6 to 7 million years ...
3 The Evolution of Meals
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Food and eating are central facets of animals’ lives. The search for and ingestion of food occupies a considerable number of the wak-ing moments in most mammals’ lives. This is especially true for primates, the mammalian order to which we belong. Primate species in the wild often spend a quarter or more of their awake time in food-related activ-ities (e.g., Janson and Terborgh, 1979; Terborgh, 1983). A diet change ...
4 Evolution, Adaptation, and Human Obesity
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In this chapter we examine what has been called the mismatch para-digm (Gluckman and Hanson, 2006) a central tenet of evolutionary medicine (Williams and Neese, 1991). In general, medicine, both human and veterinary, focuses on the mechanistic aspects of disease: the what and how of pathology. Evolutionary medicine examines the why of disease processes. For example, there are responses to infection that are common ...
5 Evolution, Adaptation, and the Perils of Modern Life
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The preceding chapters examine some aspects of our evolutionary history as they pertain to our biology. Now we explore the ways that the modern environment, interacting with our evolved biology, might make us vulnerable to sustained weight gain leading to obesity. Modern foods and the ways we eat have changed dramatically over the last 50 to 60 years, let alone from what our prehistoric ancestors ex -...
6 Energy, Metabolism, and the Thermodynamics of Life
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Obesity, at its core, results from a sustained period of positive energy balance. More energy is ingested than is expended in the processes of life. The excess energy is stored on the body, primarily as fat. The increase in adipose tissue is central to the metabolic cascades that will lead to a lessening of health. The simplistic and generally unrealistic an -swer is to reverse the process; expend more calories than are consumed. ...
7 Information Molecules and the Peptide Revolution
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In the last chapter we reviewed the concepts of energy, metabolism, and energy balance: the difference between energy intake and energy expenditure. Metabolism and energy expenditure are regulated. There are mechanisms to regulate energy intake as well. In the next two chapters we examine some of the molecules and pathways that are involved in the In this chapter we travel back in time, in some cases possibly all the ...
8 Appetite and Satiety
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We eat food; we need nutrients. When we eat, how much, how often, what kind of food depends on many things. But regard-less of when, how much, and so on, one aspect of our eating is to satisfy An organism has specifi c nutrient requirements, and evolution has produced adaptations to enhance intake of some, but not all, of those nutrients when they are scarce. The most general, hunger, motivates an ...
9 Getting Ready to Eat
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Eating requires a complex set of coordinated physical, physiologi-cal, and behavioral actions. Of course when we eat we don’t really have to think about it. We can do it easily and naturally. But when we consider it as scientists, we can see that eating is a very complex process. It is also episodic. We don’t eat all the time. We don’t even think about However, if you hadn’t eaten for a while and you smelled an enticing ...
10 The Paradox of Feeding
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The acquisition of food is a necessity for animals. Strong selective pressures have acted to produce the anatomy, physiology, and behavior that serve to enhance an animal’s ability to ingest, digest, absorb, and ultimately metabolize the nutrients necessary for survival and repro-duction. But animals do not eat constantly, even if food is always present. What are the selective pressures and adaptive functions that have shaped ...
11 The Biology of Fat
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Fat is an essential part of our bodies. Fats, or lipids, perform many functions: nutritional, hormonal, even structural. For example, myelin, which sheaths the axons and increases the speed with which nerve impulses travel, is 80% lipid. Certain fatty acids are essential for proper brain development. Indeed, brains are high-fat organs. This makes brains energetically expensive to build and maintain. It also makes them a high-...
12 Fat and Reproduction
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Men and women differ in many ways, for good biological rea-sons. This is especially true for fat and fat metabolism. Although both men and women are susceptible to obesity, they get fat in different ways, and suffer different potential health consequences. Men and women differ in the patterns of fat deposition, fat mobilization, utilization of fat as a metabolic fuel, and the consequences of both excess and insuffi cient ...
13 Genetic and Epigenetic Correlates of Obesity
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The epidemic of obesity has occurred too rapidly for it to represent genetic change in the population. However, the fact that under the same environmental and social conditions there are lean as well as obese people implies that there are intrinsic, and thus likely genetic, differences among people that either protect them from or predispose them to obesity. A concerted, ongoing effort to identify genetic correlates of obesity has ...
Conclusion: Surviving the Perils of Modern Life
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These are very exciting times for biology; our knowledge is in -creasing at an exponential rate. New scientifi c techniques allow glimpses of the very core of life, the intricate molecular mechanisms that enable animals to function. The more we learn, the more we are amazed In this book we examine a broad range of biology relevant to human obesity. Our approach is comparative and based on the foundation of ...
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Page Count: 408
Illustrations: 16 halftones, 46 line drawings
Publication Year: 2009