Scientists are replicating the toolmaking skills of prehistoric people to better understand the ways we teach and learn today.

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It’s not easy to carve a stone hand ax  – a tool that the long-extinct cousins of our species were making nearly two million years ago.

First, you’ve got to pick a suitable chunk of flint that will break the right way when you chip off pieces with another rock, bone or antler. You’ve got to strike it in the right place with the right force at the right speed, with little room for error.

If you get it right, a two-faced, teardrop-shaped hand ax emerges like a sculpture chiseled from a block of marble.

I saw a demonstration of this ancient art a few years ago at the Massachusetts Institute of Technology and I wondered how such a complex skill could have spread from person to person, down through the generations.

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Could you learn it just by watching over someone’s shoulder? Could you reverse-engineer a hand ax if you found one at an abandoned campsite?

Or could this have been one of the earliest examples of teaching?

Those are the kinds of questions that Emory University anthropologist Dietrich Stout has spent the past 15 years exploring, which he describes in this month’s cover story for the magazine Scientific American.

Stout is using techniques from archeology, neuroscience and other disciplines to understand what happens in our brains when we learn to make ancient tools.

“Making and using stone tools may require some kinds of cognitive skills that are actually good for a lot of things,” Stout told me.

For example, toolmakers must think several moves ahead, yet change direction when unforeseen obstacles require a new strategy. And they must exercise self-control by pulling back at the last second when a strike is off target.

Stout’s brain-imaging studies show that learning to make stone tools changes the brain’s wiring in ways that increase activity in regions involved in planning and self-control — and the more sophisticated the tool, the more the activity.

And why does that matter?

Some animals use simple tools, too, but Stout wonders if advances in stone toolmaking over hundreds of thousands of years made us smarter on the way to becoming human.

“The main thing is to understand what the evolutionary origins of the human mind can tell us about who we are and how we think today,” Stout said.

He’s also interested in whether teaching played a role in that evolution.

A growing number of scientists from a variety of disciplines hypothesize that teaching is a natural cognitive ability that fueled the rapid growth of human culture.

While it’s possible that our ancestors learned on their own without teaching, Stout and others think that teaching has a role because apprentices often hit plateaus in their learning. That’s when a teacher can make a huge difference in helping them reach the next level, but it’s not clear what works best.

At his lab at Emory, Stout oversees a class of students learning stone toolmaking that is being videotaped to see how much basic trial-and-error exploration students need and when teaching helps the most.

It took Stout about 300 hours of practice on his own, without a teacher, to make a stone hand ax as sophisticated as the ones discovered in England that were made half a million years ago.

“We need a lot more studies in learning and teaching,” Stout said. “The reason we don’t know a lot is because it’s actually really hard to study interesting skills, that is, skills that take hundreds or thousands of hours or even years to develop.”