How did prehistoric humans get so smart? We know that our brain volume grew from 650cc to 1,500cc before the agricultural revolution at roughly 10,000 BCE, but until now nobody was able to offer a unified theory as to why.
Tel Aviv University researchers Dr. Miki Ben-Dor and Prof. Ran Barkai suggest the reason is that humans became so skilled at hunting large animals they drove them to extinction. This spelled a need to come up with means to hunt smaller animals, according to the article published it the Journal of Quaternary Science.
The average size of land mammals was 500kg when humans first came into their own as a species, when we began to farm the size dropped to 10% on average than what it was.
The theory stands out among others as it suggests the growth of language and the brain faculties needed for long term planning, and even imagination, within one framework. The drop in the size of large animals was noted in all known areas where humans are known to have flourished.
"We correlate the increase in human brain volume with the need to become smarter hunters," explains Dr. Ben-Dor. Hunting gazelles, for example, is harder than hunting one large elephant – of which the African continent used to have six different types before humans hunted them to near extinction.
“Hunting small animals, that are constantly threatened by predators and therefore very quick to take flight, requires a physiology adapted to the chase as well as more sophisticated hunting tools,“ he explained. It is also good to have a strong memory to remember where the animals like to drink or what their migration patterns are.
"As the size of animals continued to decrease, the invention of the bow and arrow and domestication of dogs enabled more efficient hunting of medium-sized and small animals," Dr. Ben-Dor said, "until these populations also dwindled."
The theory suggests humans were happy to hunt as long as they could obtain enough food from the energy invested in it. When that became difficult near the end of the stone age, they switched to farming.
"While the chimpanzee's brain, for example, has remained stable for 7 million years, the human brain grew threefold, reaching its greatest size about 300,000 years ago,” Prof. Barkai said. In addition, just think on all the things humans invented during that time.Fire, tools, the domestication of dogs, language songs and stories.
Prof. Barkai adds that "our cousins the Neanderthals became extinct when their large prey disappeared" while the "homo sapiens decided to start over again, this time relying on agriculture."