Some vegetarian writers try to rationalize away humanity's evolutionary
past as hunter-gatherers by claiming that prehistoric humans were at best
occasional scavengers and poor hunters. A recent review article torpedos
such claims for the nonsense they are.

"Early hominid hunting and scavenging: a zooarcheological review"
M. Dominguez-Rodrigo, T.R. Pickering
Evolutionary Anthropology
2003, vol. 12, 275-282

>From p. 281:

"Thus, in summary, the preponderance of zooarcheological data indicate
that hominids in East Africa were gaining regular access to largely
fleshed ungulate carcasses and were exploiting these carcasses fully for
meat and intramuscular fat, with less emphasis on marrow harvesting.
Although Plio-Pleistocene archeofaunas and innovative actualistic
research hold the potential to modify this interpretation of the
carcass-foraging capabilities of early hominids, scenarios of hominids
as passive scavengers, relegated to the role of marrow scroungers, are
not currently supported."

Tom Billings