22
views
0
recommends
+1 Recommend
0 collections
    1
    shares
      • Record: found
      • Abstract: found
      • Article: not found

      Energetics and the evolution of human brain size.

      Nature

      Adipose Tissue, anatomy & histology, Animals, Biological Evolution, Brain, Energy Metabolism, physiology, Female, Humans, Organ Size, Species Specificity

      Read this article at

      ScienceOpenPublisherPubMed
      Bookmark
          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Abstract

          The human brain stands out among mammals by being unusually large. The expensive-tissue hypothesis explains its evolution by proposing a trade-off between the size of the brain and that of the digestive tract, which is smaller than expected for a primate of our body size. Although this hypothesis is widely accepted, empirical support so far has been equivocal. Here we test it in a sample of 100 mammalian species, including 23 primates, by analysing brain size and organ mass data. We found that, controlling for fat-free body mass, brain size is not negatively correlated with the mass of the digestive tract or any other expensive organ, thus refuting the expensive-tissue hypothesis. Nonetheless, consistent with the existence of energy trade-offs with brain size, we find that the size of brains and adipose depots are negatively correlated in mammals, indicating that encephalization and fat storage are compensatory strategies to buffer against starvation. However, these two strategies can be combined if fat storage does not unduly hamper locomotor efficiency. We propose that human encephalization was made possible by a combination of stabilization of energy inputs and a redirection of energy from locomotion, growth and reproduction.

          Related collections

          Most cited references20

          • Record: found
          • Abstract: not found
          • Article: not found

          The Expensive-Tissue Hypothesis: The Brain and the Digestive System in Human and Primate Evolution

            Bookmark
            • Record: found
            • Abstract: not found
            • Article: not found

            A theory of human life history evolution: Diet, intelligence, and longevity

              Bookmark
              • Record: found
              • Abstract: found
              • Article: not found

              The Expensive Brain: a framework for explaining evolutionary changes in brain size.

              To explain variation in relative brain size among homoiothermic vertebrates, we propose the Expensive Brain hypothesis as a unifying explanatory framework. It claims that the costs of a relatively large brain must be met by any combination of increased total energy turnover or reduced energy allocation to another expensive function such as digestion, locomotion, or production (growth and reproduction). Focusing on the energetic costs of brain enlargement, a comparative analysis of the largest mammalian sample assembled to date shows that an increase in brain size leads to larger neonates among all mammals and a longer period of immaturity among monotokous precocial species, but not among the polytokous altricial ones, who instead reduce their litter size. Relatively large brained mammals, altricial and precocial, also show reduced annual fertility rates as compared to their smaller brained relatives, but allomaternal energy inputs allow some cooperatively breeding altricial carnivores to produce even more offspring in a shorter time despite having a relatively large brain. Thus, the Expensive Brain framework explains why brain size is linked to life history pace in some, but not all mammalian lineages. This framework encompasses other hypotheses of energetic constraints on brain size variation and is also compatible with the Brain Malnutrition Risk hypothesis, but the absence of a mammal-wide correlation between brain size and immature period argues against the Needing-to-Learn explanation for slower development among large brained mammals.
                Bookmark

                Author and article information

                Journal
                22080949
                10.1038/nature10629

                Comments

                Comment on this article