<em>Australopithecus</em> (IMAGE) American Museum of Natural History Caption New research shows that a strong selection to increase brain size alone played a large role in both brain- and body-size increases throughout human evolution. This phenomenon also may have been solely responsible for the major increase in both traits that occurred during the transition from human ancestors like Australopithecus, a model of which is seen here in the American Museum of Natural History's Hall of Human Origins, to Homo erectus. Credit © AMNH/R. Mickens Usage Restrictions Can be used with appropriate credit License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.