What makes us human? Scientists just found a defining feature of the human brain in monkeys

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A new look inside monkeys brains is forcing researchers to reconsider what makes humans unique, as you can see in the video above.

It’s no surprise that humans and many types of monkeys have a lot in common; we’re both social creatures and share about 93% of our DNA. But when scientists from The Rockefeller University peeked inside four rhesus monkeys’ brains with an fMRI machine, they were still surprised to find something they’ve only ever encountered in humans: A unique choreography of brain activity, which activates when the monkeys are processing social interactions.

In humans, researchers have long believed this system is the mental network that underlies humans’ most defining feature: The ability to go farther than merely identifying other people’s behavior, to actually interpreting what they’re thinking. This “theory of mind” is the basis for how humans read situations and choose to act themselves. And it’s the bedrock of complex human society.

Finding an almost identical pathway in monkeys is remarkable, because it means that our ability to read thoughts has deep evolutionary roots. By studying the homologous network in monkeys, scientists may be able to figure out exactly how this important human ability developed.