Essentially all of human evolution took place before the introduction of domesticated plants and animals. Human subsistence was maintained through a hunter-gatherer type life-style and as a result, modern day humans consume food with the preference of early humans. When foraging under harsh conditions, food of the highest nutritional value would be more beneficial to a hungry human. Through the mechanism of natural selection, early humans who favored foods high in energy, amino acids, and other nutrients would be put at a selective advantage. By contrast, those who tended to favor other foods would be selected against.
Evidence of this preference is prevalent in every culture around the world. Meats, fats, and sugars tend to be considerably more favored than other foods. Furthermore, now that we have access to an endless supply of food, this evolutionary hangover is causing rampant health problems (obesity, diabetes) for modern day humans. Unfortunately, it is unlikely that we will ever be able to shake off this biological adaptation. This is because, despite the resulting health problems, people are still capable of reproducing and passing on the trait. Any selective pressures against our current food preference are weak at best and unlikely to ever be of any significance.
Evolution will probably not be able to affect our food preference any more; however, a powerful cultural response has been evoked instead. Fat and sugar substitutes, diet and weight loss plans, and meat flavored vegan food are some indicators of this response. Humans are developing tech fixes on a massive scale with the aim of allowing us to continue to consume the food we naturally prefer while preventing health problems. Human food preference is a perfect example of cultural evolution acting in response to natural evolution.
The following are class presentation and discussion notes from April 24, 2006.
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Human Natures: Genes, Cultures, and the Human Prospect
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Paul R. Ehrlich
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pg. 285-288
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Evolutionary Hangovers
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Human food preferences evolved from hunter gatherer diets: mostly vegetable foods, low in sugar and fat
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Hunting dangerous animals like mammoths or harvesting honey was risky but worth it for the high-calorie prize
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Now, with easy access to endless amounts of junk food loaded with sugar and fat, the food preferences that developed ago are maladaptive
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W. Roger Williams, an English physician, noted that the death rate from cancer in his country increased four fold between 1840 and 1896---he suggested that record high levels of meat consumption as well as other dietary issues new with the development of an industrial society could be related
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Fat consumption vs. death rate from prostate cancer:
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N. America and most of Western Europe have high levels of both
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Thailand, El Salvador, and Japan, by contrast, consume ~1/4 of the fat and ~1/10 the death rate
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Overall, dietary factors are believed to only have an effect on the rate of cancer cell division and don’t actually prevent the illness
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Such relationships are controversial and hard to prove; however, it is clear that modern diets can have many negative effects on health (heart disease, diabetes, cancer, etc.)
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The several hundred generations since the introduction of agriculture is insufficient to allow significant selection on food preferences
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Furthermore, people usually have time to reproduce before any possible health issues from their diet affect them---selection pressures must be relatively weak
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Micronesian island of Nauru:
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Phosphate mining between the two world wars brought great wealth to the population, allowing subsistence farmers to sit back and indulge
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Incidence of diabetes soared as high as 60%
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Between 1975 and 1987, diets remained the same and diabetes levels dropped, suggesting the effects of selective pressures
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The illness was affecting people during their reproductive years; diabetic women had fewer than half as many babies
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There must have been genetic variation within the population, favoring genes that resist the disease
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Similar events occurred with Australian Aborigines who had quick introductions to modern diets
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“Selection [is believed to have] gradually reduced the frequency of susceptible genotypes in Western populations”—explains why they don’t suffer the extremely “high levels of diet-related ills that peoples like the Nauru and Aborigines do”
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Ehrlich also mentions that food preferences are also subject to cultural evolution
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e.g. sushi restaurants springing up in the U.S. while American fast food restaurants are appearing in Japan
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e.g. the ubiquitous movement occurring in the U.S. to push for weight loss and decreased obesity levels
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Overall, Ehrlich communicates the main issue in the following quote:
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“The rich sources of energy that hunter-gatherer found rarely, and thus needed to exploit efficiently, are hardly needed by the overfed people of affluent countries today but are no less prized by them.” pg. 286
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Sociology on the Menu: An Invitation to the Study of Food and Society
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Alan Beardsworth and Teresa Keil
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pg. 193-195, 201-203, 242-243, 249-253
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Book tends to emphasize more sociological and cultural explanations for human food preference while still acknowledging possible biological causes
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The Mysterious Meanings of Meat
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Nutritional significance of meat is in the amino acids it’s composed of
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Includes essential amino acids that we cannot synthesize and, therefore, must be acquired from outside sources—these sources are “high biological value” proteins and come from eggs, meat, fish, other animal products
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“Low biological value” proteins include those from plants; no single plant has all essential amino acids so a variety must be eaten to maintain good nutrition
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Amino acid source would be another advantage to meat in addition to the fat it has
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The Idea of “Meat Hunger”
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“Why, in fact, do humans go to all the trouble of eating meat?”
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Addresses a number of points with respect to this question: 1) For a hunter-gather, it is difficult to obtain. 2) When domesticated, it is expensive to obtain—much more energy goes into growing the meat than is recovered. 3) In some cases, maintaining a population of domesticated animals is relatively efficient because they can consume food wastes and by-products; they can also graze on land unsuitable for farming
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Evolutionary explanations/suggestions: 1) With the exception of the gorilla, other animals closely related to us exhibit similar dietary patterns (including co-operative hunting). 2) Human need for a high-quality/high-energy diet is related to the development of the large brain we possess—the brain uses 20-25% of energy expended while resting. 3) Meat is highly valued in cultures around the world.
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Mentions briefly that some social scientists accept “that the complex symbolic significance which cultures ascribe to meat , are in effect, manifestations or reflections of this underlying nutritional attraction” (281)…others disagree, arguing that “the symbolic dimensions of meat…provide the principal reasons for its consumption” (202).
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Sugar and Confectionary: Sweetness in the human diet
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The Physiological Basis for the Preference For Sweetness
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“Sweetness is the characteristic taste of many attractive energy sources, such as fruits”
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Human infants have been shown to prefer sweet solutions immediately after birth—evidence for an innate preference
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“Preference for sweetness is argued to be so powerful that,…it provides an example of one of the most straightforward links between biology, individual, and culture” (243)
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The Symbolism of Sweetness
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Important to take note of how a biologically innate characteristic in our species like the preference for sweet things can have such overarching effects on our culture
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Mentions that “in spite of the cheapness and ready availability of sugar and other sweeteners in the Western world, Western cuisines rarely, if ever, contain sweet main courses”
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Such cultural evolution may have developed as a result of the negative aspects or connotations that are closely associated with sweetness: highly calorific and unhealthy, self-indulgence, sin
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“Confectionary is regarded as both food and non-food” and has taken on a number of roles in today’s society: gifts in relationships, eaten on special occasions (Christmas, Easter, other holidays)
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“Sweet foods are seen, on the one hand as delicious and attractive, and on the other as self-indulgent and potentially harmful”
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Sugar Substitutes: Americans Opt for Sweetness and Lite
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FDA Consumer, John Henkel, revised Feb 2006
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According to a 1998 survey, 144 million American adults regularly consume low-calorie, sugar free products
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Artificial sweeteners are many times sweeter, allowing fewer to be used and lowering the number of calories in foods
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FDA has approved four sugar substitutes: saccharin, sucralose, aspartame, acesulfame-K
- Saccharin (Sweet 'n Low): Discovered in 1879; 300 times sweeter than sugar; Studies have shown that saccharin causes bladder cancer in rats; however, the proportions of the of the chemical administered to rats for testing was unrealistic when compared to human consumption (equivalent of 800 diet sodas a day)
Beardsworth, Alan. Keil, Teresa. "Sociology on the Menu: An Invitation to the Study of Food and Society." London, England and New York, New York: Routledge, 1997.
Henkel, John. "Sugar Substitutes: Americans Opt for Sweetness and Lite" from The U.S. Food and Drug Administration's FDA Consumer <www.cfsan.fda.gov/~dms/fdsugar.html>. Last revised February 2006.
Maria, Segal. "Fat Substitutes: A Taste of the Future" from The U.S. Food and Drug Administration's FDA Consumer. <www.cfsan.fda.gove/~lrd/fats.html>. December 1990.
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