Rosenberg, a paleoanthropologist at the University of Delaware, specializes in pelvic morphology and has studied hominid fossils from Europe, Israel, China and South Africa.
The dawn of speech is one of the great puzzles of evolution because there's no fossil record of verbal communication for scientists to look back through.
Using a technique called Bone Histology where scientists slice up fossils into very thin sections, we can look at the internal structures found in fossils.
Thanks to well-preserved skull fossils, scientists know that it had recurved teeth for hunting, and the ear region of its skull suggests that it was adapted to hearing underwater.