In this way, the researchers say, early humans repeatedly overhunted large animals until they became extinct (or until they became so large that they disappeared from the archaeological record) and then moved on to the next largest animal, improving their breeding technologies to meet the needs of humans. new needs. сһаɩɩenɡe. Researchers also claim that about 10,000 years ago, when animals larger than deer became extinct, humans began to domesticate plants and animals to satisfy their needs, and this may be the reason why agricultural geography began in the Levant precisely. at that time.

The study was conducted by Prof. Ran Barkai and Dr. Miki Ben-Dor of the Department of Archeology and Ancient Near Eastern Cultures Jacob M. Alkow, Prof. Shai Meiri of the School of Zoology and the Steinhardt Museum of Natural History , and Jacob Dembitzer. , a research student of Prof. Barkai and Prof. Meiri, who led the project. The article was published in the journal   Quaternary Science Reviews  .

The study, unprecedented in both scope and duration, presents a comprehensive analysis of data on animal bones discovered at dozens of prehistoric sites in and around Israel. The findings indicate a continued decline in the size of game that humans use as their main food source: from giant elephants between 1 and 1.5 million years ago to gazelles 10,000 years ago. According to the researchers, these findings offer an illuminating picture of the interaction between humans and the animals around them over the last 1.5 million years.

Linear geometry of log10-transformed weighted mean body mass (in kg) per stratigraphic layer as a function of time (log10 years before present). Credit: Tel Aviv University

Professor Barkai points out two important questions currently being addressed by prehistorians around the world: What caused the mass extinction of large animals in the last hundreds of thousands of years: overhunting by humans or perhaps recurring climate changes? And what were the driving forces behind the great changes in humanity, both physical and cultural, not to mention its evolution?

Professor Barkai says that “in light of previous studies, our team proposed an original hypothesis that links the two questions: we believe that large animals disappeared due to overhunting by humans, and that the change in diet and the need to breed them progressively smaller Animals may have ргoрeɩɩɩed the changes in humanity. “In this study we test our hypotheses in light of data from explorations in the southern Levant covering several human species  over a period of 1.5 million years.”

Jacob Dembitzer adds that “we consider the Southern Levant (Israel, the Palestinian Authority, southwestern Syria, Jordan and Lebanon) as an ‘archaeological laboratory’ due to the density and continuity of prehistoric finds spanning such a long period of time. over a time. relatively small area – a huge database that is not available anywhere else in the world. Explorations, which began 150 years ago, have produced evidence of the presence of humans, starting with Homo erectus who arrived 1.5 million years ago, through the Neanderthals who lived here from an unknown time until their disappearance about 45,000 years ago. years, until modern humans (that is, ourselves) who came from Africa in several waves, beginning about 180,000 years ago.

Excavations in the Qesem cave. Credit: Tel Aviv University

The researchers compiled all the data available in the literature on animal bones found at prehistoric sites in the southern Levant, mainly in Israel. These explorations, carried out from 1932 to today, provide a rapid sequence of findings of different types of humans over a period of 1.5 million years. Since some sites comprise several stratigraphic layers, sometimes thousands of years apart, the study covered a total of 133 layers from 58 prehistoric sites, in which thousands of bones belonging to 83 animal species had been identified. From these remains, the researchers calculated the weighted average size of the animals in each layer at each site.

Professor Meiri says: “Our study tracked changes at a much higher resolution over a considerably longer period of time compared to previous research. The results were illuminating: we found a continuous and highly significant decline in the size of animals supported by humans for 1.5 million years. For example, one third of the bones left by Homo erectus at sites dating back approximately one million years belonged to elephants that weighed up to 13 tons (more than twice the weight of the modern African elephant) and provided humans with 90 % of your weight. of your food. The average weight of all animals transported by humans at that time was 3 tons, and elephant bones were found in almost all sites until 500,000 years ago.

“About 400,000 years ago, humans who lived in our region, early ancestors of Neanderthals and Homo sapiens, appear to have hunted primarily deer, along with some larger animals weighing almost a ton, such as cattle and horses. Finally, in sites inhabited by modern humans, from about 50,000 to 10,000 years ago, approximately 70% of the bones belong to gazelles, an animal that does not weigh more than 20 to 30 kg. Other remains found at these later sites come mainly from fallow deer (around 20%), as well as smaller animals such as hares and tortoises.”

Deer bones with сᴜt marks. Credit: Tel Aviv University

Jacob Dembitzer says that “our next question was: What caused the disappearance of the large animals? A widely accepted theory attributes the extinction of large species to climate changes over the centuries. To test this, we collected climatic and environmental data for the entire period, covering more than a dozen cycles of glacial and interglacial periods. These data included temperatures based on oxygen-18 isotope levels and precipitation and vegetation evidenced by carbon-13 values ​​from the local Soreq cave. “A series of statistical analyzes correlating the size of the animals with climate, precipitation and the environment showed that climate and climate change had little or no impact on the animals’ extinction.”

Dr. Ben-Dor says, “Our findings allow us to propose a fascinating hypothesis about the development of humanity: humans always preferred to conserve the largest animals available in their environment, until they became very rare or became extinct, which which forced prehistoric dinosaurs to look for the next largest. As a result, to obtain the same amount of food, each human species that appeared in the Southern Levant was forced to raise smaller animals than its predecessor and, consequently, had to develop more advanced and effective technologies. So, for example, while spears were sufficient for Homo erectus to kill elephants at close range, modern humans developed bows and arrows to kill fast-running gazelles at a distance.”

Prof. Ran Barkai with an ancient elephant bone. Credit: Tel Aviv University

Professor Barkai concludes that “we believe our model is relevant to human cultures around the world. Furthermore, for the first time, we claim that the driving force behind the constant improvement of human technology is the continuous increase in game size. Ultimately, it may well be that 10,000 years ago in the southern Levant animals became too small or too large to provide humans with enough food, and this could be related to the advent of agriculture. Furthermore, we confirmed the hypothesis that the extinction of   large animal  was caused by humans, who time and again destroyed their own livelihood through excessive hunting. Therefore, we can conclude that humans have always cared for their environment, but were generally smart enough to find solutions to the problems they had created, from the bow and arrows to agricultural geography. The environment, however, has always paid a despicable price.”