IAS / School of Science Joint Lecture

Remarkable, Yet Not Extraordinary: The Human Brain as a Linearly Scaled-up Primate Brain and Its Associated Cost


The human brain has long been considered to be special: it is larger than expected for the size of our body, it alone consumes 20% of the energy required by the whole body despite amounting to only 2% of body mass, it grew extraordinarily fast over the last million years; it defies the laws of evolution. But does it really? This talk will reevaluate these concepts in the light of new findings on the numbers of neurons that compose the brains of different species; how much energy they cost, and how that curbs increases in brain and body mass; and how our ancestors found a way to circumvent the energetic limitation imposed by their raw diet, which allowed humans to amass what no other animal has afforded to amass (while still obeying the scaling rules that apply to other primates): an enormous number of neurons in the cerebral cortex.

About the speaker

Prof. Suzana Herculano-Houzel received her PhD in Neuroscience from the Université Pierre et Marie Curie in 1998. She was postdoctoral fellow at the Max Planck Institute for Brain Research from 1998 to 1999. She joined the Federal University of Rio de Janeiro in 2002, and is currently Associate Professor of Biomedical Sciences. She is also Head of the Laboratory of Comparative Neuroanatomy.

Prof. Herculano-Houzel’s main research interest is the evolutionary origin of diversity in the nervous system, with an emphasis on the comparison of the human brain with other species. Through the examination of the cellular rules that govern brain scaling in development and evolution, she investigates the relationships between numbers of neuronal and glial cells and brain size across animal species and orders, and how they are related to neuronal connectivity, scaling of the cortical white matter, and folding of the cortical grey matter; how final adult brain size and cellular composition are achieved in development, and hence what modifications of the developmental program affect numbers of cells in the brain and lead to modified adult brain size in evolution and pathologies; how numbers of neurons and synapses differ across species and relate to cognitive abilities, especially across humans and other, larger-brained species; and how the metabolic requirements of the brain scale with numbers of brain neurons, and its consequences for brain evolution and pathologies.

Prof. Herculano-Houzel received awards including the Scholar Award in Understanding Human Cognition, Jabuti Literature Award, José Reis Award on Science Communication, etc.


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