Content area
Full Text
Brazilian neuroscientist, Suzana Herculano-Houzel, is the author of The Human Advantage. A former associate professor and head of the Laboratory of Comparative Anatomy at the Federal University of Rio de Janeiro, she received the Scholar Award in Understanding Human Cognition from the James S. McDonell Foundation in 2010. She is the author of six books for the general public on the neuroscience of everyday life. Between 2008-2011 she was a writer and presenter of the TV series Neurologica. In May 2016 she moved to the United States and joined Jon Kaas's lab at Vanderbilt University.
What is it about the human brain that makes it special? How is it that humans have such extraordinary cognitive abilities? The author tackles these broad questions, and presents a strong argument to support her claims. Herculano-Houzel argues that human brains are not special, but they are remarkable. That is, they are not special in light of evolution. Human brains are susceptible to the rules of primate evolution. Primates have an advantage over other mammals regarding brain structure; their brains have evolved such that neurons are added to the brain without the large increases in average cell sizes seen in other mammals. Primate brains have evolved differently than non-primate brains. As an example, cows and chimpanzees have brains that are similar in mass, but the chimpanzee can be expected to have at least twice as many neurons as a cow. Human brains are scaled up primate brains. Contrary to the popular claim that the human brain is larger than can be expected for body type, the author argues the number of brain neurons as a function of body mass is what can be expected for a non-great ape primate. Neuroscientists have always thought that the human brain is large relative to the size of the body that contains it, when directly comparing to brain and body size of great apes. If our body is smaller, it follows that are brain should be smaller, and yet it is three times larger in terms of mass. However, Herculano-Houzel's data show that when great apes are excluded humans show the same relationship between their body mass and number of brain neurons as that of other primates. "[I]t is not humans that are...