Brains and guts in human evolution: The Expensive Tissue Hypothesis

Aiello, Leslie C.

doi:10.1590/s0100-84551997000100023

Cited by 60 publications

(34 citation statements)

References 41 publications

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“…Cebus, Saimiri), while those with relatively small brains have the lowest quality diets (e.g. Alouatta), consistent with the traditional perceptions that diet and brain size are linked in these animals [11,18,20,32]; however, these extremes appear to drive the correlation and the overall explained variance is quite low (see the electronic supplementary material). At this level of explanatory power, DQ is not highly predictive of encephalization.…”

Section: Discussionsupporting

confidence: 70%

Dietary quality and encephalization in platyrrhine primates

Allen

Kay

2011

Proc. R. Soc. B.

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The high energetic costs of building and maintaining large brains are thought to constrain encephalization. The 'expensive-tissue hypothesis' (ETH) proposes that primates (especially humans) overcame this constraint through reduction of another metabolically expensive tissue, the gastrointestinal tract. Small guts characterize animals specializing on easily digestible diets. Thus, the hypothesis may be tested via the relationship between brain size and diet quality. Platyrrhine primates present an interesting test case, as they are more variably encephalized than other extant primate clades (excluding Hominoidea). We find a high degree of phylogenetic signal in the data for diet quality, endocranial volume and body size. Controlling for phylogenetic effects, we find no significant correlation between relative diet quality and relative endocranial volume. Thus, diet quality fails to account for differences in platyrrhine encephalization. One taxon, in particular, Brachyteles, violates predictions made by ETH in having a large brain and low-quality diet. Dietary reconstructions of stem platyrrhines further indicate that a relatively high-quality diet was probably in place prior to increases in encephalization. Therefore, it is unlikely that a shift in diet quality was a primary constraint release for encephalization in platyrrhines and, by extrapolation, humans.

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Section: Discussionsupporting

confidence: 70%

Dietary quality and encephalization in platyrrhine primates

Allen

Kay

2011

Proc. R. Soc. B.

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“…Thus, reductions in organ or tissue mass could theoretically decrease the body's overall energy costs and compensate for the high metabolic demands of the brain. This perspective forms the basis of the Expensive Tissue Hypothesis, which posits that the increased metabolic requirement of an enlarged brain among hominids is offset by a concomitant reduction in gut size since both are metabolically "expensive" tissues (Aiello and Wheeler, 1995;Aiello, 1997;Aiello et al, 2001). …”

Section: Body Compositionmentioning

confidence: 99%

The Energetics of Encephalization in Early Hominids

Snodgrass

Leonard

Robertson

2009

The Evolution of Hominin Diets

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Bioenergetics, the study of the use and transfer of energy, can provide important insights into the ecology and evolution of early hominids. Despite a relatively large brain with high metabolic demands, contemporary humans and other primates have resting metabolic rates (RMRs) that are similar to those of other mammals. As a result, a comparatively large proportion of their resting energy budget is spent on brain metabolism among humans (~20-25%) and other primates (~8-10%) compared to other mammals (~3-5%). To understand this shift in energy budget, Aiello and Wheeler's Expensive Tissue Hypothesis (ETH) posits a metabolic trade-off-a reduction in gut size with brain size increase-to explain this phenomenon. Here, we explore the interrelationships between brain size, body size, diet, and body composition using comparative data for humans, non-human primates, and other mammals. Among living primates, the relative proportion of energy allocated to brain metabolism is positively correlated with dietary quality. Contemporary humans fall at the positive end of this relationship, having both a high quality diet and a large brain. Thus, high costs associated with the large human brain are supported, in part, by energy-rich diets. Although contemporary humans display relatively small guts, primates as a group have gut sizes that are similar to non-primate mammals. In contrast, humans and other primates have significantly less skeletal muscle for their size compared to other mammals. These comparative analyses suggest that alterations in diet quality and body composition were necessary conditions for overcoming the constraints on encephalization. Fossil evidence indicates that brain expansion with the emergence of Homo erectus at about 1.8 million years ago was likely associated with important changes in diet, body composition, and body size.

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“…We found a tight correlation with the HF-diet mouse brain composition with respect to these TGs to the HF-food diet: correlation coefficient r 2 =0.760 in comparison to control chow r 2 = 0.264 [1]. Dietary quality has played a prominent role in theories of human evolution in general and the evolution of the human brain in particular (reviewed by [5]). Ideas of brain evolution centring on dietary quality until present (this study) not been confined to humans and human evolution [6].…”

Section: Introductionmentioning

confidence: 85%

Hunter-prey correlation between migration routes of African buffaloes and early hominids: Evidence for the “Out of Africa” hypothesis

Ginneken¹,

Meerveld²,

Wijgerde³

et al. 2017

Integr Mol Med

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Based on the similarity of migration routes of early bovines and early hominids (direct hunter-prey correlation) we postulate the hypothesis that early hunter hominids followed the herds of buffaloes and that the dispersal of early hominids pan-Africa is directly correlated to the historical migration of the African buffalo. This reasoning gives supportive evidence for the "Out of Africa" hypothesis. In addition, brain fattening ("brain steatosis") has previously been demonstrated after exposure of a juvenile mouse strain to a bovine lard High-Fat diet and starvation -as an evolutionary paradox-in whole brain using LCMS-techniques [1]. Here we postulate the hypotheses that accumulation of specific Triacylglycerols from bovine lard (large amounts of unsaturated C:50-1; C:50-2; C:52-2; C:52-3; C:54-3;C:54-4 and C:56-3 TGs) in early hominid brain could have contributed to encephalization in human evolution. Following this lipidomics based scientific approach [2] we gave supportive evidence for the "Out of Africa" hypothesis.

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Brains and guts in human evolution: The Expensive Tissue Hypothesis

Cited by 60 publications

References 41 publications

Dietary quality and encephalization in platyrrhine primates

Dietary quality and encephalization in platyrrhine primates

The Energetics of Encephalization in Early Hominids

Hunter-prey correlation between migration routes of African buffaloes and early hominids: Evidence for the “Out of Africa” hypothesis

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