Tel Aviv University scientists have suggested that the “ice age diet” – in which Neanderthals ate high amounts of protein from large prey – accounted for their anatomical differences from Homo sapiens, the forerunner of modern man.Neanderthals, who were heavyset and had larger rib cages and wider pelvises than the more modern and advanced Homo sapiens, lived on Earth until some 40,000 years ago. Neanderthals were quite similar to Homo sapiens with whom they sometimes mated, but they were also different, being shorter and stockier.Prof. Avi Gopher, Prof. Ran Barkai and doctoral candidate Miki Ben-Dor – all from TAU’s Department of Archeology and Ancient Near Eastern Cultures – coauthored the study, which was recently published in the American Journal of Physical Anthropology.According to the researchers, the total dependence of Neanderthals on large animals to meet their fat and protein needs may provide a clue to their eventual extinction, which took place at the same time as the beginning of the demise of giant animals or Megafauna in Europe some 50,000 years ago. The TAU scientists are now researching this subject.According to the just-published article, the bell-shaped Neanderthal rib cage or thorax had to evolve to accommodate a larger liver, the organ responsible for metabolizing great quantities of protein into energy. This heightened metabolism also required an expanded renal system (enlarged bladder and kidneys) to remove large amounts of toxic urea, possibly resulting in the wide Neanderthal pelvis.“The anatomical differences between the thoraxes and pelvises of Homo sapiens and Neanderthals have been well-known for many years, but now we’re approaching it from a new angle – diet,” said Gopher. “During harsh ice age winters, carbohydrates were scarce and fat was in limited supply. But large game, the typical prey of the Neanderthal, thrived,” added Ben-Dor. “This situation triggered an evolutionary adaptation to a high-protein diet – an enlarged liver, expanded renal system and their corresponding morphological manifestations. All of these contributed to the Neanderthal evolutionary prowess.”“In our 2011 paper, which dealt with the demise of Homo erectus in the Levant, we had already tapped into the notion that diet played a major role in human evolution,” said Barkai. “We argued then that high fat consumption was one of the most important solutions to the predicament presented by human evolution. Humans are limited in the amount of protein they are able to turn into energy; protein provides just 30 percent of their overall diet. The solution, therefore, was to consume more fat and more carbohydrates when they were seasonally available.“We found that, in the case of the Neanderthals, an acute shortage of carbohydrates and a limited availability of fat caused their biological adaptation to a high-protein diet,” Barkai explained.Numerous animal experiments have already demonstrated that a high-protein diet is likely to produce enlarged livers and kidneys.“Early indigenous Arctic populations who primarily ate meat also displayed enlarged livers and the tendency to drink a lot of water, a sign of increased renal activity,” said Ben-Dor.