Effects of Brain Evolution on Human Nutrition and Metabolism

Abstract

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.

The evolutionary roles of nutrition selection and dietary quality in the human brain size and encephalization

“…Leonard and colleagues (2007) [55] have shown a positive correlation between brain size and dietary quality for 33 different primate species, including humans, after adjusting for differences in body size. Thus, across all primates, greater energy allocation to brain metabolism is associated with consumption of a higher quality, more energy-rich diet.…”

The Importance of Dietary Carbohydrate in Human Evolution

“…These changes are proposed to have occurred with a shift from a high-volume, low-energy diet to a lowvolume, high-energy diet (Aiello and Wheeler 1995;Leonard et al 2003Leonard et al , 2007Milton 2003;Snodgrass et al 2009). By 1.8 million years ago the hominin gut is thought to have been effectively modern in shape with a reduced stomach and long small intestine (Aiello and Wheeler 1995).…”

“…One argument for increased meat consumption as the catalyst for brain expansion, and for the development of certain patterns of social organization, is founded on the dietary need for very long-chain omega-3 polyunsaturated fatty acids, such as docosahexaenoic acid (DHA; (Kaplan et al 2000;Bunn 2007;Leonard et al 2007;Brenna and Carlson 2014). These fatty acids are critical structural components of brain, retina, and other nerve tissues, and are essential for the growth and functional development of the brain in infants, and for normal brain func-tion in adults (Innis 2008).…”

“…These fatty acids are critical structural components of brain, retina, and other nerve tissues, and are essential for the growth and functional development of the brain in infants, and for normal brain func-tion in adults (Innis 2008). Dietary DHA availability has been proposed as a limiting factor in brain evolution (Leonard et al 2007). Although meat is a source of these essential fatty acids (Howe et al 2006), DHA can also be obtained directly from other dietary sources, or it can be synthesized from other fatty acids such as ␣-linolenic acid (ALA), which is present in oils from ocean fish, eggs, seed oils, and various leafy plant foods (Brenna and Carlson 2014).…”

Is Cetacean Intelligence Special? New Perspectives on the Debate

“…Table 1. The above image highlights the current available statistics for the cerebral cortex of cognitive sophisticated terrestrial mammal species as well as several species of cetaceans (see [2,3,12,13,17,29,30,48,53,67,70,[77][78][79][80][81][82][83][84][85]). The table on top of the figure provides estimations of different physiological parameter for the brains of great apes, humans, and African elephants.…”