Much of modern cannibalism revolves around the ritual consumption of one's adult enemies, but apparently this was not what was practiced by H. antecessor. The case for Neandertal cannibalism was advanced by White and Toth, but it's my impression that it's controversial. Since the Upper Paleolithic, modern humans have certainly devised numerous new ways of being cruel to one another, but it seems that cannibalism is not one of them. Certainly, our more recent ancestors have imbued meaning and ritual to the process, but it does seem that the act could very well be performed by a symbol-free culture.
Hominid Hunting has more.
J Hum Evol. 2012 Sep 1. [Epub ahead of print]
Intergroup cannibalism in the European Early Pleistocene: The range expansion and imbalance of power hypotheses.
Saladié P, Huguet R, Rodríguez-Hidalgo A, Cáceres I, Esteban-Nadal M, Arsuaga JL, Bermúdez de Castro JM, Carbonell E.
In this paper, we compare cannibalism in chimpanzees, modern humans, and in archaeological cases with cannibalism inferred from evidence from the Early Pleistocene assemblage of level TD6 of Gran Dolina (Sierra de Atapuerca, Spain). The cannibalism documented in level TD6 mainly involves the consumption of infants and other immature individuals. The human induced modifications on Homo antecessor and deer remains suggest that butchering processes were similar for both taxa, and the remains were discarded on the living floor in the same way. This finding implies that a group of hominins that used the Gran Dolina cave periodically hunted and consumed individuals from another group. However, the age distribution of the cannibalized hominins in the TD6 assemblage is not consistent with that from other cases of exo-cannibalism by human/hominin groups. Instead, it is similar to the age profiles seen in cannibalism associated with intergroup aggression in chimpanzees. For this reason, we use an analogy with chimpanzees to propose that the TD6 hominins mounted low-risk attacks on members of other groups to defend access to resources within their own territories and to try and expand their territories at the expense of neighboring groups.