Study Showed How The Human Brain Grew After Large Animals Went Extinct

Dr. Miki Ben-Dor and Prof. Ran Barkai of Tel Aviv University's Jacob M. Alkow Department of Archaeology have presented a recent paper that offers an original unifying theory for the human species' physiological, behavioral, and cultural evolution from its first emergence about two million years ago to the agricultural revolution (around 10,000 BCE).

According to the article, humans originated as large-animal hunters, ultimately causing their extinction. Humans evolved higher cognitive capacities as they adapted to hunting small, fast prey species, as demonstrated by the most noticeable developmental change-the rise in brain capacity from 650cc to 1,500cc.

To date, no unifying theory for the major events of human prehistory has been suggested. Quaternary Journal presented the novel hypothesis.

In recent years, more and more data has accumulated that humans were a significant force in the disappearance of big mammals, causing humans to switch to hunting smaller game, first in Africa and then worldwide. When humans first arrived in Africa 2.6 million years ago, the average size of land mammals was equivalent to 500kg.

This number had fallen by more than 90% before the advent of agriculture, to a few tens of kilograms.

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Population Correlation

According to the researchers, the dwindling size of the game and the need to chase small, swift creatures caused humans to demonstrate cunning and boldness-an evolutionary mechanism that necessitated increased brain volume and ultimately contributed to the creation of language, which allowed the sharing of knowledge about where the prey could be found. According to the philosophy, all means were used to accomplish a common goal: body energy conservation.

According to the researchers, early humans were apex (top) hunters that engaged in hunting big game for the bulk of their evolution. These animals supplied humans with high-fat levels, an important energy source. They allowed a higher energy return than a small game, as they made up most of the biomass available for hunting.

Elephants used to be present in Africa in six distinct groups, accounting for more than half of all herbivores' biomass killed by humans. According to preliminary reports from East Africa, Homo sapiens only arrived there after the number of elephant populations in some areas collapsed. When the researchers compared the size of animals found in archaeological cultures representing various types of humans in east Africa, southern Europe, and Israel, they discovered that there was a substantial decrease in the incidence of animals weighing over 200kg, which was followed by a rise in the volume of the human brain in all situations.

Human Brain

Dr. Ben-Dor explains, "We associate the rise in human brain volume with the desire to become smarter hunters." The need to hunt hundreds of gazelles instead of one elephant, for example, put a long-term evolutionary burden on human brain systems, as humans now spent even more resources on both action and thinking processes. Hunting small animals, which are continually attacked by predators and thus very easy to run, necessitates chase-adapted physiology as well as more specialized hunting tools.

Fast monitoring necessitates rapid decision-making, which involves a remarkable knowledge of the animals' behavior-information that must be retained in a broader memory."

Adaptation

Humans have had a great deal of experience in ecological adaptation, "Dr. Ben-Dor agrees. "As animal numbers shrank, the invention of the bow and arrow, as well as the domestication of dogs, made for more effective hunting of medium-sized and small animals-until their numbers dwindled as well.

Size Change

When species shrank in size toward the end of the Stone Age, humans had to spend more resources hunting than they could recover. The Agricultural Movement, which included the domestication of both animals and plants, took place during this time. The size of humans' brains shrank as they settled into permanent villages and became farmers, to the present amount of 1300-1400cc. This resulted because, with non-flying domesticated plants and animals, there was no longer a need to dedicate extraordinary cognitive ability to the role of hunting."

Prof. Barkai points out, "Although the chimp's brain has remained unchanged for 7 million years, the human brain has evolved three times its original size, hitting its height about 300,000 years ago. In addition to increased brain volume, evolutionary pressure compelled humans to use language, fire, and sophisticated tools such as the bow and arrow, adapt their arms and shoulders to throwing and hurling tasks, and their bodies to the long chase, improve stone tools, domesticate dogs, and eventually domesticate the game itself, and turn to agriculture."

Who is Responsible?

Prof. Barkai continues, "It's important to note that our opinion is not predetermined. Humans are to blame for their own misfortune. They triggered extinctions by focusing on hunting the biggest species. Wherever humans emerge, whether homo erectus or homo sapiens, we see large animals' mass extinction sooner or later. The cost of relying on big animals was high.

Humans sabotage their own life. However, while other animals, such as our Neanderthal cousins, died when their massive prey vanished, homo sapiens opted to start again, this time depending on agriculture."

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