Humans simultaneously evolved the ability to use tools, teach tool usage

New research suggests the human ability to teach was key to the process of cumulative cultural evolution.

In a new paper, published this week in the journal Proceedings of the Royal Society B, researchers at the University of Exeter contend that natural selection favored humans capable of both using complex tools and teaching others how to do the same.

According to researchers, the two abilities, using tools and teaching tool usage, likely evolved simultaneously.

"Humans have an unrivaled ability to pass knowledge down the generations," senior study author Alex Thornton said in a news release.

"Traditional theories assumed that cumulative cultural evolution requires specialized processes, like teaching, to transmit information accurately, but this cannot explain why these processes evolved in the first place," said Thornton, a researcher at Exeter's Center for Ecology and Conservation in Cornwall, England.

For their study, scientists recruited hundreds of participants to form creation "chains."

Half of the creation chains produced a simple tool, a boat made of waterproof paper, while the other chains of participants created a more complex tool, a basket made of pipe cleaners. Both tools were used to carry marbles -- the more marbles, the better.

Each chain yielded ten generations of technological improvements, or design iterations.

In each chain, participants were able to either look at the tool made by the previous generation, watch the creation of the previous generation's tool or talk to the maker of the previous design iteration.

The three different forms of communication allowed some level of teaching to inform subsequent design iterations.

"Simple and complex tools generally improved down the generations, and for simple tools this improvement was about the same in all three study conditions," said study co-author Amanda Lucas, researcher at the University of Exeter.

"With complex tools, teaching consistently led to more improvement compared to other conditions. Teaching seemed to be particularly useful in allowing new, high-performing designs to be transmitted," said Lucas, a researcher at the University of Exeter.

Researchers say their creation chains involved a diverse range of people from the Cornwall community, from club sports captains and museum curators to librarians and community gardeners.

"This meant that our study represented a diversity of ages, backgrounds and skills, which is important as many of these types of experiments, that intend to investigate something essential about being human, recruit a narrower sample of university students only," Lucas said.

The findings suggest there is something essentially human about not just technological innovation, but the act of teaching.

"Our findings point to an evolutionary feedback loop between tool-making and teaching," Thornton said. "This suggests that our ancestors could have started to make modest cumulative improvements to simple tools without the need for teaching, but as tools became more complex, teaching started to become advantageous."

Researchers theorize that as humans got better at teaching technological skills, more efficiently passing knowledge from generation to generation, groups were able to produce increasingly complex and effective tools.