MONKEYS may have a primitive version of the human ability to put ourselves in another's shoes.
Intelligent animals such as apes can intuit others' intentions, suggesting they have some theory of mind capability. But only humans can reason that others may not hold their own beliefs.
To study this difference, Rogier Mars of the University of Oxford and colleagues scanned 36 people's brains. Using an algorithm, they created a map of how an area associated with theory of mind is connected to brain regions linked to abilities such as face recognition and interpretation.
Next, the researchers scanned 12 macaque brains for a similar pattern of connections. An area involved in facial recognition had a similar pattern, suggesting involvement in abstract thought.
That doesn't necessarily mean the structures share a function, Mars says. Theory of mind is probably a spectrum of ways of thinking, he says, and humans got better at it as they evolved.
Laurie Santos of Yale University says the structural differences may one day tell us why non-human primates lack the ability to think about others' beliefs.