Modern humans in Israel – 400,000 years ago

Researchers at Tel Aviv University have solved the riddle of the appearance of Modern humans in Israel – 400,000 years ago

The researchers: Changes in nutrition led to the disappearance of Homo erectus and the appearance of Modern humans who were faster and had greater skills and abilities.

A crucial step in the biological and cultural evolution of humans took place in the Middle East 400 thousand years ago – a result of adaptation to a different diet following the disappearance of elephants.

The researchers, who last year reported the surprising discovery of Modern humans’ teeth in Qesem Cave near Tel Aviv, preceding by 200,000 years the African Homo sapiens, propose now a reconstruction of the circumstances leading to its emergence specifically in the Middle East and specifically 400,000 years ago. Their paper „Man the Fat Hunter – the demise of the Homo erectus and the emergence of a new hominin lineage in the Middle Pleistocene (ca. 400 kyr) Middle East” was published last Friday (Dec. 9th ) in the scientific journal PLoS One.

„It’s all in the diet” explain Dr. Ran Barkai, Miki Ben Dor, Prof. Avi Gopher and Prof. Israel Hershkovitz of Tel Aviv University (TAU) in a paper challenging common knowledge regarding ancient human diet and the circumstances leading towards biological and cultural changes in human evolution.


The disappearance of the elephants preceded the appearance of Modern humans

The researchers state that elephants’ bones with cut and breakage marks, indicating consumption as food by Homo erectus, were found in many sites of the Acheulian culture which is the culture associated with Homo erectus worldwide. In contrast with their abundance in the Acheulian (roughly 1.5 million to 400,000 years ago in the Middle East), no elephant remains were found in sites belonging to subsequent cultures in the Middle East beginning 400,000 years ago. An analysis of bone assemblages from Gesher B’not Yaakov (Acheulian site dated to nearly 800 thousand years ago) showed that the elephant was a very significant animal in the Homo erectus’ nutrition, providing approximately 60% of his animal sourced calories. It became clear then that the disappearance of the elephant – a huge animal whose caloric value is equal to many tens of fallow deer for example – placed an enormous burden on Homo erectus, who was forced to hunt many more smaller and more evasive animals in order to compensate for the loss of meat and fat.

Having confirmed the importance of elephants to Homo erectus’ nutrition in the Middle East, the researchers turned to look at the circumstances surrounding the evolution of Modern humans in Africa. They found out that indeed also in Africa elephants have disappeared from archeological sites together with the Acheulian culture and also in Africa the disappearance of elephants from post – Acheulian sites preceded the appearance of Modern humans. In Africa, however, the process has taken place 150,000 years later than in the Middle East. The researchers therefore concluded that there was a connection between the disappearance of elephants and the appearance of Modern humans – something that has not been suggested previously.


Hunting small animals and new skills

In an attempt to fully comprehend the effect that the disappearance of elephants might have had on the Homo erectus in terms of caloric consumption the researchers constructed a bio-energetic model of hominids’ nutrition. One important conclusion drown from the model was that the Homo erectus was dependent on a significant amount of animal fat for his survival. It is known that humans are limited in the amount of protein that they can process to energy and other researchers have pointed out a limitation on the digestion of non-cooked plant foods. In the absence of evidence for the habitual use of fire during the Acheulian, the present paper researchers came to the unavoidable conclusion that the Homo erectus had to complete his nutrition with a significant amount of animal fat. It is not very well known but it is an uncontested fact that many animals, including our relatives the apes, are nourished by a very significant quantity of fat. Fat in those animals is produced in the colon from plant fiber by bacteria. Gorilla, for example, obtains 60% of its energetic requirements from saturated fats that are produced in its large colon by bacteria from plant fiber. To accommodate the energetic needs of the growing human brain, the energy expensive colon has shrunk to a quarter of the size relative to the chimpanzee for example, creating a shortage of fats in human nutrition. The researchers claim that filling this shortage with animal fat makes the most sense as it is biologically the most parsimonious solution as far as food processing goes.

Thus, for a long period of time, starting ca. one and a half millions years ago and until 400,000 years ago Homo erectus in the Middle East hunted large and fat rich animals. The elephant was prominent among those animals.

Understanding the Homo erectus’ dependency on animal fat sheds light on another aspect of the evolutionary stress caused by the disappearance of elephants. Elephants have a higher quantity of fat relative to body weight than smaller animals and contrary to smaller animals they lose little fat during dry seasons. The researchers say that lives for the Homo erectus during the summers after the disappearance of elephants must have been grim indeed. The dry vegetal landscape coupled with the physiological ceiling on the consumption of protein forced Homo erectus to obtain fat from many smaller and more evasive animals whose fat reserves were dwindling as the summer progressed. Thus a loop was created whereby increased hunting activity meant increased food and specifically fat requirements that were obtainable only at a higher caloric costs.

Examination of the anatomical, morphological and cultural changes that the Modern humnmas have gone through show indeed an adaptation to hunting of a larger quantity of smaller more evasive animals. The capabilities of Modern humans enabled more sophisticated and efficient trucking and hunting of animals, especially fatter, prime aged animal as evident at Qesem Cave. They also made it possible to develop more sophisticated social and technological skills like hunting in a group, food sharing, control of fire and production of new and innovative stone tools, enabling better energetic utilization of a larger number of smaller animals. Evidence for such behaviors were found in Qesem cave and published in previous papers. Morphological changes like lighter weight and relative elongation of the lower limbs contributed to Modern human’s improved agility and more efficient locomotion.

In addition to being the first attempt at explaining the reasons for the evolution of the Modern humans this study also challenges the “Out of Africa” paradigm dominating research on the evolution of Homo sapiens during the last decades. In recent years this paradigm has been challenged by new discoveries from Europe, China and other localities. These are now setting the stage for a new understanding of the human story in general and the emergence of Modern humans in particular.

The researchers are currently expanding their study in an attempt to reconstruct other events in human evolution using the bio-energetic model they have developed in this research.