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  • Print publication year: 2012
  • Online publication date: April 2012

10 - The mass of the human brain: is it a spandrel?

from Part II - Hominin morphology through time: brains, bodies and teeth

Summary

Abstract

The current chapter examines allometric exponents as they apply to the evolution of the size, or mass, of the modern human brain relative to the mass of the body. The mass of the brain is considered as a single level of organisation of the nervous system and is treated separately to other levels of organisation. A comprehensive dataset is used to examine the relationship between brain and body mass in primates and hominids. This analysis allows us to postulate that the evolution of the size of the human brain can, for the most part, be accounted for by scaling with body size. There appears to be a minimum of two potential adaptive events that have led to alterations in the scaling laws that help explain the actual mass of the human brain. These two events occur at the origin of primates and the origin of the hominid lineage. These scaling laws appear to obviate much of the need for adaptationist explanations in terms of the evolution of the mass of the human brain.

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