WASHINGTON, D.C.—According to a report in The International Business Times, a recent study suggests that the sizes of human ancestor brains and teeth did not evolve together. Modern humans differ from other hominins in that they have large brains and small posterior teeth. It had been previously thought that as brain size increased, and hominins began making stone tools to process food, the size of their teeth decreased. Aida Gómez-Robles of George Washington University and her colleagues analyzed eight different hominin species, and found a relatively constant rate of change for tooth evolution, but different rates of brain evolution. “The fastest rate in the evolution of the brain occurred in the branch of the evolutionary tree predating the divergence of Homo erectus from the lineage leading to Neanderthals and modern humans,” she said. The study did not investigate the possible behavioral and ecological factors that may have influenced tooth and brain sizes. For more on hominin brain evolution, go to “Hungry Minds.”
