Developmental problems: This fragment of a child's skull discovered at Olduvai Gorge, Tanzania, shows the oldest known evidence of anaemia caused by a nutritional deficiency
A fragment of a child's skull dating back some 1.5 million years offers some of the earliest evidence that early humans were hunters who ate meat regularly, scientists say.

The piece of bone discovered in the Olduvai Gorge, Tanzania, has signs of nutritional deficiencies commonly caused by a lack of meat in its owner's diet, suggesting early man needed meat to thrive.

The discovery by a team of researchers led by Manuel Domínguez-Rodrigo from Complutense University, Madrid, suggests early human ancestors began eating meat much earlier in history than previously believed

The skull fragment identified is thought to belong to a child somewhat younger than two and shows bone lesions that commonly result from a lack of B-vitamins in the diet.

Previous studies have suggested that early hominids ate meat, but whether it was a regular part of their diet or only consumed sporadically was not certain.

Now, the researchers suggest that the bone lesions present in this skull fragment provide support for the idea that meat-eating was common enough that not consuming it could lead to anaemia.

Nutritional deficiencies such as anemia are most common at weaning, when children's diets change drastically.

The research suggest that the child may have died at a period when he or she was starting to eat solid foods lacking meat.

Alternatively, if the child still depended on the mother's milk, the mother may have been nutritionally deficient for lack of meat.

Both cases imply that 'early humans were hunters, and had a physiology adapted to regular meat consumption at least 1.5 million years ago', say the researchers.

The evidence that early man ate meat as an integral part of his diet comes as leading scientists are beginning to warn that the entire world may have to become almost entirely vegetarian to handle spiralling populations.

Researchers from the Stockholm International Water institute warned in August that animal-based food will have to drop to just 5 per cent of our total calories by 2050.

'There will not be enough water available on current croplands to produce food for the expected 9 billion population in 2050 if we follow current trends and changes towards diets common in western nations,' the researchers warned.

It is believed that if current population growth continues, there could be an additional 2billion people alive by 2050. Humans currently get about 20 per cent of their protein from animal-based products.

The latest findings were reported in a paper published yesterday in the open access journal PLoS ONE.