Over hundreds of thousands of years, ancient humans hunted the largest animals they could find to extinction before turning to smaller and smaller game and eventually agriculture, a group of Israeli researchers said Tuesday after analyzing animal remains from dozens of previously explored sites.
The Tel Aviv University study, which analyzed research on thousands of bones from 83 animal species found since 1932, concluded that humans have long been expert at exhausting the best possible resource available to them before moving on to the next best. While the process led to the mass extinction of megafauna toward the end of the Pleistocene, the need to adapt may have also eventually led to farming and the rise of civilization, the researchers found.
“We think that large animals went extinct due to overhunting by humans,
and that the change in diet and the need to hunt progressively smaller animals may have propelled the changes in humankind,” said researcher Prof. Ran Barkai.
For the study, scientists tracked hunting practices in and around Israel over the past 1.5 million years by compiling data from research literature on 58 dig sites that have been excavated since 1932. The material
The team found early humans favored large prey as the biggest payoff relative to effort, but that the size of their game gradually declined as they killed off the largest species.
Around 1-1.5 million years ago, the hunters targeted giant elephants, and had worked their way down to gazelles around 10,000 years ago.
At that time, humans started domesticating plants and animals to feed themselves, although it’s not certain that sparse game led to the agricultural revolution, which occurred in the area at about the same time.
The researchers analyzed data from animal bones previously found at dozens of prehistoric sites in Israel, the Palestinian Authority, southwest Syria, Jordan and Lebanon.
The region acts as an “archaeological laboratory” due to the density and continuity of archaeological evidence, and the long time period covered by the finds, said researcher Jacob Dembitzer.
The area was not only inhabited by modern humans during the time frame, Dembitzer points out — Homo erectus arrived 1.5 million years ago, Neanderthals were in the region until around 45,000 years ago, and anatomically modern humans showed up around 180,000 years ago.
Based on the animal remains, the researchers calculated the average size of the animals in each geological layer. The average size of prey continually declined across the 1.5 million year time frame.
For the early Homo erectus sites from about a million years ago, a third of the bones were from elephants that weighed up to 13 tons, more than twice the size of modern African elephants.
The massive animals provided the early humans 90 percent of their food, and were found at nearly all sites until 500,000 years ago.
By 400,000 years ago, the humans in the region, ancestors to Neanderthals and Homo sapiens, were mostly hunting deer, along with some larger animals weighing around 1 ton, including wild cattle and horses.
In sites used by modern humans dating to 50,000-10,000 years ago, 70% of the bones were from gazelles, which weight 20-30 kilograms (44-66 pounds). Other bones at these sites came from fallow deer, hares and turtles.
The average size of prey 10,500 years ago was 1.7% the size of average prey from 1.5 million years ago.
“Humans always preferred to hunt the largest animals available in their environment, until these became very rare or extinct, forcing the prehistoric hunters to seek the next in size,” said researcher Dr. Miki Ben-Dor.
The researchers then compared the data on animal bones to climatic and environmental data, covering over a dozen cycles of glacial and interglacial periods. They analyzed data comparing animal size with climate, precipitation and environment, and found no correlation between extinction and climate.
The researchers hypothesized that the search for smaller game led to technological evolution by succeeding human species. Homo erectus was able to kill elephants with spears from close range, but modern humans needed to develop the bow and arrow to kill fast-running gazelles from farther away, for example.
By 10,000 years ago, the remaining animals may have been too small or rare to provide humans with enough food, which could be related to the start of agriculture, the researchers said.
“We believe that our model is relevant to human cultures everywhere,” said Prof. Ran Barkai. “We argue that the driving force behind the constant improvement in human technology is the continual decline in the size of game.”
The researchers also said that humans “time and time again destroyed their own livelihood through overhunting.”
“We may therefore conclude that humans have always ravaged their environment but were usually clever enough to find solutions for the problems they had created,” Barkai said. “The environment, however, always paid a devastating price.”
The study was conducted by Tel Aviv University’s Jacob Dembitzer, Prof. Ran Barkai and Dr. Miki Ben-Dor of the Jacob M. Alkow Department of Archaeology and Ancient Near Eastern Cultures, and Prof. Shai Meiri of the School of Zoology.
The research will be published in the peer-reviewed journal Quaternary Science Reviews next month.