The manufacture of stone tools and their use to access animal tissues 
by Pliocene hominins marks the origin of a key adaptation in human 
evolutionary history. Here we report an in situ archaeological 
assemblage from the Koobi Fora Formation in northern Kenya that 
provides a unique combination of faunal remains, some with direct 
evidence of butchery, and Oldowan artifacts, which are well dated to 
1.95 Ma. This site provides the oldest in situ evidence that 
hominins, predating Homo erectus, enjoyed access to carcasses of 
terrestrial and aquatic animals that they butchered in a well-watered 
habitat. It also provides the earliest definitive evidence of the 
incorporation into the hominin diet of various aquatic animals 
including turtles, crocodiles, and fish, which are rich sources of 
specific nutrients needed in human brain growth. The evidence here 
shows that these critical brain-growth compounds were part of the 
diets of hominins before the appearance of Homo ergaster/erectus and 
could have played an important role in the evolution of larger brains 
in the early history of our lineage.

http://pos-darwinista.blogspot.com/2010/06/dieta-de-proto-humanos-incluia-animais.html