Why Are Our Brains so Big?

Humans possess, with respect to our body size, unusually large and extremely cognitively skilled brains. The neocortex in particular, a part of the cerebrum, is proportionally three times larger than that of our closest relation, the chimpanzee. Researchers from the German Primate Center — the Leibniz Institute for Primate Research and the Max Planck Institute of Molecular Cell Biology and Genetics — explain why the human brain is so unique in its size and complexity. Their experiments with mice showed that human-specific sections of a certain gene family work together during embryonic development in such a way as to stimulate brain growth.

Specifically, the NOTCH2NLB gene ensures that the progenitor cells of brain cells multiply more heavily, while the NBPF14 gene develops new neurons out of those precursor cells. The number of brain cells is not the only thing that increases, however, as the cerebral cortex gains folds to a greater extent as well. This folding (called gyrification) is vital, because the enlarged neocortex would otherwise simply not fit inside the tight space of the cranium.

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