Humans are less nutritious than other forms of meat, findings show, indicating complex social motivations may be behind our ancestors’ cannibalism

Cannibalism among prehistoric humans was more likely to have been driven by social reasons than the need for a hearty meal, research suggests.

Evidence of cannibalism, in the form of cut marks, tooth marks and tell-tale bone breakage has been found at a number of prehistoric sites, including in France, Spain and Belgium, revealing that our ancestors as well as other hominins such as Neanderthals and Homo antecessor at least occasionally ate each other.

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But how common cannibalism was and to what extent it was driven by the need for nutrition has been a matter of debate, with remains from some sites showing evidence of ritual treatment.

The latest study adds weight to the idea that cannibalism might have been driven by more than the necessity of hunger.

Totting up the nutritional value of the human body, James Cole, an expert in human evolution from the University of Brighton, reveals that an adult male of about 66kg contains roughly 144,000 calories, with skeletal muscle accounting for just over 32,000 calories, kidneys providing 376 calories and the spleen 128 calories.



But the nutritional value of a host of animal species whose remains – showing signs of butchery – were found at the sites, are higher. The skeletal muscle of a mammoth offered 3,600,000 calories, a horse 200,100 calories and a red deer 163,680 calories. Saiga antelope, however are on a par with humans, with their skeletal muscle containing 31,500 calories.



“What this suggests is that we aren’t terribly nutritious,” said Cole, author of the research published in the journal Scientific Reports. “We are a fairly small animal really and we don’t have much flesh and meat or fat to us, and we certainly wouldn’t necessarily have done in the past either.”

Cole adds that while smaller animals such as birds and hares were eaten by early hominins despite their low calorie content, it would have been far more challenging to opt for cannibalism, as hominins can “fight, run and think their way out of the hunt”.

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Cole admits that the analysis is based on the nutritional value of a small group of modern male humans, while Neanderthals were more muscular. He says the research suggests cannibalism might have been driven by a complex range of motivations.



“[The study] is not saying that no, we didn’t eat each other for nutritional reasons in the past, I think what it is suggesting is, is that the only explanation?” he said. “Maybe there is more of a social driver here, not ritual specifically, but social.”



Among the possibilities, he suggests, is that cannibalism might have been opportunistic, with individuals being eaten when they died of natural causes, or that it might have been linked to territorial defence.



Paul Pettitt, professor of Palaeolithic archaeology at the University of Durham, welcomed the research, pointing out that primates including bonobos and chimpanzees also show evidence of cannibalism.

“Such behaviours clearly form something like a behavioural ritual – an unconscious act that stemmed from common activities central to group behaviour like eating meat,” he said. “Somewhere along the line of human evolution this behaviour turned from behavioural rituals to ritualised behaviour, and as Coles shows very well, evidence does clearly reveal that eating human meat was not exclusively about survival.”

Silvia Bello of the Natural History Museum agrees with Cole that Palaeolithic cannibalism was probably more often practised as a choice rather than for survival, but adds that unpicking the motivations behind that choice is a tricky business.

“Was cannibalism practiced as a funerary ritual, or was it just a way to eat whatever was available? I’m not sure the evidence can really help to pick one or the other,” she said. “We just need to keep looking for new methods of analyses and new sites to better understand this behaviour.’