Evidence has been brought to light that our Stone Age ancestors developed techniques in hunter-scavenging, to fuel their evolution. The research study was carried out by a team from Baylor University (USA) and their conclusions prove quite interesting. The theory proposed by the team is that increases noted in brain size and body dimensions required more energy to fuel their increased activity. This led to wider ranging activities to gather the food required.
     The study centered around a two million year old site in Kenya, known as Kanjera South. The inhabitants at that time are commonly known as Oldowan hominin. The team measured the gradual growth in brain and frame size and noted some interesting facts about the fossil evidence found at the site. The first sets of fossils were of a type of small antelope. Not remarkable in itself but, when you take into account the fact that all the bones were found, from the top of the head to the hoof, the conclusion being drawn that the animals were hunted and brought back to be butchered and eaten.
     So how did they conclude that they also scavenged? Well other remains belonged to a much larger wildebeest sized animal, but only the head. Normally, after a kill in the wild by carnivorous animals, the entire carcass would be devoured, including the bones. But no animal could penetrate the thick skull. A tool-wielding hominin could and the heads were scavenged to enable them to extract the highly nutritious brain.
     The study is deemed to be so important that Joseph Ferraro, assistant professor of anthropology at Baylor University is quoted as saying "Considered in total, this study provides important early archaeological evidence for meat eating, hunting and scavenging behaviours - cornerstone adaptations that likely facilitated brain expansion in human evolution, movement of hominins out of Africa and into Eurasia, as well as important shifts in our social behavior, anatomy and physiology".  

Edited from ScienceDaily (10 May 2013)