Scientists had to consider how primates think in order to develop the right experiments to study them.

Question: Why are Capuchin monkeys such good models for the rnstudy of human cognition?
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rnLaurie Santos: So the Capuchins that I study are really distantlyrn related, but they’re actually a great model for human cognition for a rncouple reasons. One is that being a primate that kind of branched off rnabout 35 million years ago, they actually tell us something about what rnhuman evolution, human cognition, probably looked like a really long rntime ago. So it actually gives us insight not just into our very recent rnphylogenetic past as studies with chimpanzees might do, but Capuchins rnactually tell us something about you know, really phylogenetically old rnsimilarities that we might share with other primates.
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rnQuestion: How do primate relationships resemble human relationships?rn
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rnLaurie Santos: One cool thing about primates is that they, like rnus, are extremely social creatures.  So, they grow up in a context of rnsocial groups, they’re around other kind-specifics—other individuals of rnthe same species—and the social relationships they form really affect rntheir entire lives.  So, it affects what kind of food they’re going to rnget based on who they hang out with and what rank they are.  rnHigh-ranking individuals have easy access to food; where as low ranking rnindividuals may have to wait their turn.  It affects the kinds of matingrn success they can get, the kind of alliances they form and the way the rnsort of set up their little social groupings actually can affect just rnhow well they do in terms of natural selection.  So, social groups are rnreally important for most primate species.
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rnQuestion: Why did it take scientists so long to figure out what rnprimates know about each other's minds? 
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rnLaurie Santos: One of the reasons it took scientists so long to rnfigure out how to ask monkeys about what they know about other minds is rnthat oftentimes researchers were trying to set up studies that might rnmake sense to a human, but probably don’t make sense to a monkey. 
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rnSo, one kind of study actually involved a setup where a human was tryingrn to help a primate get a piece of food that was hidden.  So, different rnpieces of food are hidden, the monkey can’t see where they are, but the rnhuman was kind of looking and pointing at one of these pieces of food.  rnIn general, primates did really badly on this, embarrassingly badly. rnEven with training, they kind of never got it.  But that actually makes rnsense, like never in the monkey’s life would have ever intentionally cuern a human experimenter to where a piece of food was.  This is just a rnsituation which was totally weird. 
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rnSo, the insight that we as scientists had was "Let’s use the situations rnthat monkeys are naturally using to deceive us, maybe this is where theyrn will actually show us that they understand something." And now, five orrn 10 years later, there’s tons of studies suggesting exactly that.

Recorded May 21, 2010
Interviewed by Andrew Dermont