"Discovery of Israeli Archaeologists: Human's Evolution is Not Limited to Themself, Their Tools Have Also Evolved!"
Dr. Miki Ben-Dor and Prof. Ran Barkai of Tel Aviv University have served up a paper rounding out their Universal Theory of Human Evolution. Not only did our brains have to evolve as the prey available to us grew smaller and fleeter; our tools had to evolve too, they demonstrate.
"Everybody agrees that stone tools changed over time, but nobody tried or managed to explain why. The only possible explanation is that early humans grew smarter, but again nobody asked why that happened," says Barkai. This is the first study to connect the dots.
Over the last 1.5 million years, the average body mass of animals in the southern Levant diminished by more than 98 percent, from an average of 3,000 kilograms (about 6,615 pounds) to 50 kilos by 15,000 years ago, Ben-Dor and Barkai reported in 2021, together with Shai Meiri and Jacob Dembotzer. Separate studies found animal size decline elsewhere in the world during the Pleistocene.
That is a stunning statistic and, to a degree, the decline parallels the emergence of the Homo genus and its spread. Whatever our culpability in their decline, our survival required us to grow cleverer and craftier in order to catch ever smaller, fleeter prey to feed our voracious appetite for meat (and fat), Ben-Dor and Barkai postulated in their groundbreaking Unified Theory of Human Evolution (also 2021).
Now, Ben-Dor and Barkai demonstrate in a new paper published in the journal Quaternary that, as hypothesized, our stone tools apparently “evolved” in keeping with our shrinking prey and growing brain, as we adapted to the diminishing returns of hunting progressively smaller, faster animals.
“The decline in prey size would have represented a significant challenge for early humans, pushing them towards increasing adaptability and innovation in their hunting practices,” they explain, which would have influenced their social structures, cultural practices and survival strategies.
What's the difference? Theoretically, hunting an elephant before the advent of gunpowder took more balls than brains, and brute strength. But hunting a deer is a very different matter. You can brain a slow-moving elephantid with massive spears or mortally wound a rhino with a sufficiently heavy stones, but the lightning-fast deer will laugh at your evil machinations from afar. As the biggest animals became scarcer and ultimately extinct, weapons based on strength had to be supplanted by precision-focused weapons to wound an animal in flight, Ben-Dor and Barkai postulate.
To substantiate their hypothesis that our weapons had to evolve in tandem with our cognitive ability as animal size diminished, Ben-Dor and Barkai analyzed five case studies: in South Africa, East Africa, Spain, France and the Levant, from the Early and Middle Stone Ages. Their conclusion? As animals grew smaller, so did our weapons. Manufacturing smaller, more precise tips for spears and, later, arrows would have required greater skills and planning, they suggest, which is indicative of parallel cognitive development.
Key to their thesis is that mega-herbivores – of which the elephant is one – have thick deposits of fat. Our lineage has been carnivorous for about 2 million years, but we can’t live on muscle mass alone. From a certain proportion of protein intake, we develop nitrogen poisoning. Small animals are not only small, they’re lean, and the bottom line is you get less bang for your spear. Humans and our ancestors needed to conserve the energy they expended on the hunt, hence precision would become increasingly important.
Much prehistoric archaeology is based on stone tools, which survive the ages while wooden tools and bones decay. Barkai and Ben-Dor describe the history of these tools as we know it.
Crude stone tools were being used to process carcasses over 3 million years ago in eastern Africa. Which hominins were doing that, we do not know, but the researchers note the presence of Paranthropus fossils at the Kenyan site Nyayanga. But when did the spear, a whole other level of technology, arise?
The story of the spear presumably to hunt animals to eat not each other seems to have begun half a million years ago with sharpened wooden shafts. Objects believed to have been wooden spears have been found at Clacton in the UK from 427,000 years ago, but the site of Schoningen in Germany presents the first uncontested evidence for long and pointed wooden spears from 330,000 years ago.
These were most probably used as both "throwing spears" and "thrusting spears," Barkai says; and were used to hunt horses, although also elephant remains were found on site and the spears could have used to hunt these giants as well. Throwing sticks, most probably used as early version of boomerangs, were also found at Schoningen.
“Most probably wooden spears were used 1.5 million years ago,” adds Ben-Dor, noting that hand axes were being made then, and that must have been more difficult than sharpening a stick. “But wood being wood, no remains have been found earlier than Clacton,” he adds. Whether they were “throwing spears” or “thrusting spears” is hard to say.
Unequivocal evidence of the next stage, stone-tipped spears, only emerges in the Middle Paleolithic 300,000 years ago, according to Ben-Dor and Barkai (who stress that they’re not talking about the entire technological repertoire, only tools associated with hunting game).
Some suspect stone-tipped spears emerged in South Africa as much as half a million years ago, but that is based on indirect evidence of marks at the base of the stone tip, suggestive of possible hafting (gluing or otherwise attaching to a wooden shaft).
A hafted spear and knife.Credit: Paul Kozowyk / Lab for Artefact
Killing with a spear would have constituted progress for the archaic hominins. Ben-Dor and Barkai mention that, based on modern use of such implements, thrusting or throwing spears could have been used to lame the large-bodied prey, which would then be battered to death – a gruesome technique they refer to as “persistence hunting.”
In any case, the advent of sharpened wooden spears and/or throwing sticks sharpened at both ends would be followed in the Middle Pleistocene by stone-tipped spears on wooden shafts, though they don’t rule out that the technique may have emerged earlier than 300,000 years ago.
So we have cruder tools followed by wooden spears, followed by hafted stone-tipped spears. That would be followed in a new wave of hunting technology by the bow and arrow, spear throwers and darts, which were infinitely more efficient than a mere spear at catching the fast-reacting smaller mammals that remained, such as the deer and gazelle. .
Evidence from South Africa suggests that the bow and arrow may have emerged over 64,000 years ago, but they only became prevalent in the Late Stone Age and were only used by our species, Homo sapiens.
We do not know exactly when dogs joined us in the hunt. Evidence for their companionship goes back at least 14,000 years in the Levant, and as much as 23,000 years in Siberia, and some suggest an even deeper co-history. We just note that some prehistoric peoples not only embraced the dog but ate it too.
Anyway, all this boils down to the fact that as the animals grew smaller, so did the stone tips of our weaponry, as Ben-Dor and Barkai demonstrate in great detail, continent by continent. “Reduction of point size has been a prominent trend since their appearance in the Middle Paleolithic,” they write – from large crude spearheads to exquisitely crafted tiny arrowheads.
Last year in Jerusalem, an archaeological team led by Prof. Shimon Gibson found the first-ever evidence from the Neolithic in the context of the Old City: an exquisitely crafted stone arrowhead the size of pinkie nail, found on Mount Zion. It would have been perfect to do for a pigeon or a rat, while elephants had been extinct in Jerusalem for 400,000 years by then.
Back to the paper. Barkai and Ben-Dor do qualify that once arrows emerged, this technology was used on a vast range of animal sizes (and plausibly on objectionable people too, though there’s little evidence for prehistoric homicide by stone tip). "There is one case of a Natufian skeleton with a small lunate embedded in its spine," Barkai observes. But it's an outlier and could have been a hunting accident.
But the trend of prey size/tip size is clear and they break new ground in proposing correlations between all this: as the big animals died out, we had to hunt ever smaller ones, and had to develop the smarts and the technology to do it.
Ben-Dor and Barkai qualify the conclusions in the paper by stressing that their results should be considered “exploratory” because of the small sample size. But everywhere they looked, they found association between mega-herbivore decline and the transition to smaller, better refined tools – such as hafted stone points (among both Neanderthals and sapiens), which could have been more efficient in the hunt of medium sized animals such as wild cattle and giant deer than mere sharpened sticks.
Barkai has long postulated that the elephant and its ample fat were crucial to deep human evolution. In the Levant, the emergence of advanced Levallois technology in the late Acheulean period correlated with elephant extinction locally. “In all but one case (Olorgesailie, in Kenya), mega-herbivore declines were not directly associated with climate change,” they add.
An alternative theory they mention for the contracting size of bones of prey in fossil-hominin-contexts is the cave life. The earliest known cave habitation by a hominin creature was about 2 million years ago, but our occupation of caves picked up between the early and late Middle Pleistocene. Indeed, would you rather carry home a boar or a mammoth?
Barkai and Ben-Dor contend, though, that this theory has things backward. “It is not the increased dwelling in caves that presents a faulty picture of prey size decline. It was the decline in mega-herbivore reliance in the late Middle Pleistocene that allowed humans to dwell in caves more often,” they say.
Today, the only continent that has true mega-fauna as we once knew them is Africa (if we exclude the anaconda from the equation – we shouldn’t, because those reptiles can be 8.5 meters long (28 feet) and weigh a quarter-ton, but the point is clear). In Africa too, mega-fauna have become increasingly rare. People who hunt without guns nowadays, such as the indigenous people in the Kalahari, use the whole gamut of technology, from bow and arrow to spears of different types. It all depends on what you’re hunting.
Which leads us to one last point. There is actually little research into the relative effectiveness of a prehistoric stone-tipped spear as opposed to a sharpened stake. But in the Kalahari, Tyua hunters claim spears are better than bows and arrows for killing large animals because it either kills the poor beasts on the spot, or leads to enough blood loss to weaken the animal relatively quickly, the authors point out.
“We can infer that spear stone tipping provides a larger interior wound area than wooden spear tips,” they write. “Weapons kill by bleeding and damaging vital organs. Thus, increased bleeding from the larger wound should shorten the escape/pursuit stage,” they elaborate. Another upside: the faster the prey bleeds out and dies, the lesser the probability of losing it to a passing hyena.
And while stone tips have a propensity to break, the bright side – at least from the hunter’s perspective – is that the fragment stays in the animal and may kill it faster, again reducing the likelihood of loss to an itinerant carnivore. Hence the proposition that the hafted stone tip constituted another advance in the pursuit of dinner in an ever-contracting menu.
A groundbreaking study by researchers from Tel Aviv University (TAU) tracks the development of early humans’ hunting practices over the last 1.5 million years as reflected in the animals they hunted and consumed. The researchers claim that at any given time early humans preferred to hunt the largest animals available in their surroundings, which provided the greatest quantities of food in return for a unit of effort.
In this way, according to the researchers, early humans repeatedly overhunted large animals to extinction (or until they became so rare that they disappeared from the archaeological record) and then went on to the next in size, improving their hunting technologies to meet the new challenge. The researchers also claim that about 10,000 years ago, when animals larger than deer became extinct, humans began to domesticate plants and animals to supply their needs, and this may be why the agricultural revolution began in the Levant at precisely that time.
The study was conducted by Professor Ran Barkai and Dr. Miki Ben-Dor of TAU’s Jacob M. Alkow Department of Archaeology and Ancient Near Eastern Cultures, Professor Shai Meiri of TAU’s School of Zoology and Steinhardt Museum of Natural History, and Jacob Dembitzer, a research student of Professors Barkai and Meiri, who led the project. The paper was published in the journal Quaternary Science Reviews.
The study, unprecedented in both scope and timespan, presents a comprehensive analysis of data on animal bones discovered at dozens of prehistoric sites in and around Israel. Findings indicate a continual decline in the size of game hunted by humans as their main food source, from giant elephants 1-1.5 million years ago down to gazelles 10,000 years ago. According to the researchers, these findings paint an illuminating picture of the interaction between humans and the animals around them over the last 1.5 million years.
Professor Barkai says that the study addresses two major issues presently under consideration by prehistorians: What caused the mass extinction of large animals over the past hundreds of thousands of years – overhunting by humans or perhaps recurring climate changes? And what were the driving forces behind great changes in humankind – both physical and cultural – throughout its evolution?
“In light of previous studies, our team proposed an original hypothesis that links the two questions: 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,” Professor Barkai says. “In this study we tested our hypotheses in light of data from excavations in the Southern Levant covering several human species over a period of 1.5 million years.”
“We considered the Southern Levant to be an ‘archaeological laboratory’ due to the density and continuity of prehistoric findings covering such along period of time over a relatively small area – a unique database unavailable anywhere else in the world,” Dembitzer explains. “Excavations, which began 150 years ago, have produced evidence for the presence of humans, beginning with Homo erectus who arrived 1.5 million years ago, through the neanderthals who lived here from an unknown time until they disappeared about 45,000 years ago, to modern humans (namely, ourselves) who came from Africa in several waves, starting around 180,000 years ago.”
“Our study tracked changes at a much higher resolution over a considerably longer period of time compared to previous research,” Professor Meiri says. “We found a continual, and very significant, decline in the size of animals hunted by humans over 1.5 million years. For example, a third of the bones left behind by Homo erectus at sites dated to about a million years ago, 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 their food. The mean weight of all animals hunted by humans at that time was 3 tons, and elephant bones were found at nearly all sites up to 500,000 years ago.
“Starting about 400,000 years ago, the humans who lived in our region – early ancestors of the Neandertals and Homo sapiens – appear to have hunted mainly deer, along with some larger animals weighing almost a ton, such as wild 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 weighs no more than 20-30kg. Other remains found at these later sites came mostly from fallow deer (about 20%), as well as smaller animals such as hares and turtles.”
“Our findings enable us to propose a fascinating hypothesis on the development of humankind: 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,” Dr. Ben-Dor continues. “As a result, to obtain the same amount of food, every human species appearing in the Southern Levant was compelled to hunt smaller animals than its predecessor, and consequently had to develop more advanced and effective technologies. Thus, for example, while spears were sufficient for Homo erectus to kill elephants at close range, modern humans developed the bow and arrow to kill fast-running gazelles from a distance.”
“We believe that our model is relevant to human cultures everywhere,” Professor Barkai notes. “Moreover, for the first time, we argue that the driving force behind the constant improvement in human technology is the continual decline in the size of game. It may well be that 10,000 years ago in the Southern Levant, animals became too small or too rare to provide humans with sufficient food, and this could be related to the advent of agriculture. In addition, we confirmed the hypothesis that the extinction of large animals was caused by humans, who 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, from the bow and arrow to the agricultural revolution. The environment, however, always paid a devastating price.”
