Two extinct human relatives, Homo erectus and Paranthropus boisei, were found living and possibly interacting in Kenya about 1.5 million years ago, according to a study led by Kevin Hatala of Chatham University in Pittsburgh, PA. The discovery of their fossil footprints provides unique insights into their anatomy, locomotion, and behavior during their shared existence. This study highlights the role of competition and environmental adaptation in human evolution. Hatala is an associate researcher in the Department of Human Origins at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany.