Prehistoric humans may not have feasted on human flesh just to get much-needed calories, new research suggests.

An archaeologist has worked out how many calories can be derived from eating different parts of the human body.

And his research has revealed that human flesh is less calorific than the meat of large prehistoric animals including woolly rhinos, red deer and mammoths.

An archaeologist has worked out how many calories can be derived from eating different parts of the human body (pictured)

HOW MANY CALORIES ARE IN A HUMAN? Skin: 10,280 calories Bones: 25,330 calories Skeletal muscle: 32,370 Brain, spinal cord and nerves: 2,706 Heart: 650 calories Spleen: 130 calories Body fat: 49,940 calories Liver: 2,570 calories Lungs: 1,956 calories Kidneys: 376 calories Advertisement

Human bones marred with man-sized teeth marks have been found in caves and tombs across the world, leading scientists to conclude that our ancestors ate flesh.

Scientists have previously suggested that early humans turned cannibal to get a much-needed protein boost when food was scarce.

But new research suggests our early ancestors may have actually feasted on human flesh as part of a cultural or social ritual.

'Episodes of Palaeolithic cannibalism have frequently been defined as 'nutritional' in nature, but with little empirical evidence to assess their dietary significance,' said Dr James Cole from the University of Brighton.

For his research, Dr Cole studied the calorific value of human meat in comparison to that of other animals.

He focused on nine previously reported fossil sites where researchers have found evidence of cannibalism, like marks on the bones that indicated butchery.

New research suggests our early ancestors may have actually feasted on human flesh as part of a cultural or social ritual (file photo)

Over two dozen human bones (pictured) were discovered in a Spanish cave have revealed the cannibalistic practices of the Mesolithic people. The bones are covered in marks from stone tools, fire, and human teeth

The sites were dated to between roughly 14,000 years ago to more than 900,000 years ago, which falls within the Paleolithic period the study focused on.

Five involved our evolutionary cousins the Neanderthals, two involved our own species, and the rest were other extinct members of the human evolutionary branch.

His question: How many calories would the bodies at each site provide?

To estimate that, he first used previously published data to conclude that eating an average-sized modern-day man could yield up to about 144,000 calories.

The markings identified on the human remains were found to line up with the markings seen on common prey of the Mesolithic hunters, including ibex, red deer, wild boar, fox, and rabbit

He then adapted that to the age ranges of the bodies.

Even if all the bodies at a site were consumed in a single episode, he concluded, the energy payoff would be no more than what a hunter could get from a single large animal like a mammoth, a woolly rhino or a bear.

'You're dealing with an animal that is as smart as you are, as resourceful as you are, and can fight back in the way you fight them,' Dr Cole said.

Maybe in some cases, our ancestors ate companions who had died for an easy meal, Dr Cole said.

But his main point is that usually, the cannibalism was probably driven by some social or cultural factors rather than just nutrition.

Human teeth are known to leave behind double arch punctures, isolated triangular pits, and shallow linear marks that distinguish them from other predators. These can be seen above

For example, it may have followed episodes of violence, as in defending territory, he said.

Dr Cole said: 'Results show that humans have a comparable nutritional value to those faunal species that match our typical body weight, but significantly lower than a range of fauna often found in association with anthropogenically-modified hominin remains.'

'This could suggest that the motivations behind hominin anthropophagy may not have been purely nutritionally motivated.

'It is proposed here that the comparatively low nutritional value of hominin cannibalism episodes support more socially or culturally driven narratives in the interpretation of Palaeolithic cannibalism.'

The research was published in Scientific Reports.