Effects of Brain Evolution on Human Nutrition and Metabolism

Department of Anthropology, Northwestern University, Evanston, IL 60208, USA.
Annual Review of Nutrition (Impact Factor: 8.36). 02/2007; 27(1):311-27. DOI: 10.1146/annurev.nutr.27.061406.093659
Source: PubMed


The evolution of large human brain size has had important implications for the nutritional biology of our species. Large brains are energetically expensive, and humans expend a larger proportion of their energy budget on brain metabolism than other primates. The high costs of large human brains are supported, in part, by our energy- and nutrient-rich diets. Among primates, relative brain size is positively correlated with dietary quality, and humans fall at the positive end of this relationship. Consistent with an adaptation to a high-quality diet, humans have relatively small gastrointestinal tracts. In addition, humans are relatively "undermuscled" and "over fat" compared with other primates, features that help to offset the high energy demands of our brains. Paleontological evidence indicates that rapid brain evolution occurred with the emergence of Homo erectus 1.8 million years ago and was associated with important changes in diet, body size, and foraging behavior.

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Available from: William R. Leonard, Dec 28, 2013
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    • "In the nineties, bioenergetics began to offer a significant amount of underlying information on human evolution, pointing out the metabolic consequences of some physiological adaptations , as hominins' encephalization (Martin, 1981; Foley and Lee, 1991; Leonard and Robertson, 1992; Aiello and Wheeler, 1995), thermoregulation (Aiello and Wheeler, 2003; Churchill, 2006) body size (Leonard and Robertson, 1994; Wheeler, 1999), physical activity (Leonard, 2010b) or locomotion (Cordain et al., 1998; Foley and Elton, 1998; Wheeler, 1999). In more recent years, many researches continue highlighting the importance of energy dynamics for hominin adaptations (Aiello and Key, 2002; Leonard et al., 2007; Wall-Scheffler et al., 2007; Froehle and Churchill, 2009; Halsey and White, 2012; Mateos et al., 2014), which is justified by a number of reasons. Firstly, the pursuit of energy from food, its consumption and, finally, its availability for biological and cultural processes are essential factors in human life history and ecology (Ulijaszek, 1995). "

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    • "In humans, the colon represents only 20 % of the total volume of the digestive tract, whereas in apes it is about 50 % (Milton 1999, 2003). The sizeable colons of most large-bodied primates permit fermentation of low-quality plant fibres, allowing for extraction of energy in the form of volatile fatty acids (Leonard et al. 2007). Thus, humans, having small colons, are relatively poor in utilising uncooked plant fibre. "
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    • "Nevertheless, it is the energy consumed by human muscles during locomotion which is almost twice as low compared with, for instance, in chimpanzees (332 versus 564 kcal/day) [22] providing enough energy for brain development and function. The consequence is that humans' brains are three times bigger than the brains of chimpanzees, and brain metabolism accounts for 25% of the basal metabolic rate in humans and only 7 to 8% in other primate species [26]. Overall, there seems to be sufficient scientific support to suggest that the increase of human brain size and metabolism has been possible because of a change of locomotion, higher central fat depot storage [27], and (although not addressed in this review) a change of food intake (see review [24]). "
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