- [Narrator] Funding for the secret life of scientists, is provided by the Alfred P. Sloan Foundation.

(soft music) - I'm a psychologist and I'm interested in the way people think about the world.

A lot of people have of a misconception that psychology is about sitting on the couch, complaining about your problems, crazy people.

The world of experimental psychology is actually much bigger than that.

I'm interested in the smart things that people do and also the dumb things that people do.

So I try to get at these questions by studying monkeys.

Why, if you're interested in humans, would you wanna study monkeys?

Studying actual humans is sometimes little bit complicated.

The upshot is that monkeys share a lot of the smart things and a lot more of the dumb things.

I think that was it.

Feels like kind of speed dating.

(soft music) A lot of time when I tell family members or people I meet at cocktail parties that I'm a psychologist they say, "Oh, you gotta study me.

And I say, "No, no, no I study monkeys."

Everybody thinks about the puzzles in psychology.

Everybody wonders why can't I just go on the diet I'm supposed to go on?

Or why can't I save for the down payment on my home that I really wanna care about?

Or why did she fall in love with him?

- We're going to be so happy together.

- Despite all the progress we have in neuroscience and biology and physics we still know relatively little about what makes us tick.

Of course, humans didn't evolve in a world with Twitter and cell phones and computers and all this stuff that we use all the time.

We actually evolved in the Savannah.

So if we really wanna gain insight, what are we built for?

What are the strategies that natural selection prepared us for?

Let's you get rid of all the human specific stuff like culture and language and so on.

And that's why we turn to monkeys.

They provide this wonderful window into what humans would look like in the absence of all that stuff.

So we wanted to see whether the monkeys could deal with the economic choices.

So our first challenge was to actually give monkeys some money.

We actually set up a little monkey market.

And the way we did that was we introduced monkeys to tiny metal tokens that they could trade for food.

Rather than just give them all the food and fruit and stuff they eat for the day, they get to buy it themselves.

And the monkeys actually picked this up very, very quickly.

What we first discovered, was that monkeys are actually very similar to humans when it comes to buying their food.

So if you give monkeys a market in which one kind of food goes on sale, so now you can get double the amount of apples for your token, they'll actually shop and buy more apples just like humans do.

They're actually smart in the same ways that humans are smart.

So we could look at the monkey's economic choices in the same spots that human economists look at human economic choices really what they're willing to pay and what they wanna buy.

(soft music) (typewriter types) Darwin definitely because he figured out all these things that were correct about the way the world works.

And Freud figured out all these things that aren't really true.

(typewriter types) Jane Goodall, she was the pioneer.

She did it first.

(typewriter types) I would definitely be a bonobo.

Bonobos are kind of more of the hippie primate.

(typewriter types) That's a secret.

(laughs) (typewriter writes) No, very dangerous.

(typewriter types) Beck's "Loser" which begins with "In the time of chimpanzees I was a monkey."

(typewriter types) "Curious George".

(typewriter types) All my monkey dreams evolve them escaping and doing terrible things.

(typewriter types) The cutest monkey habit is actually a gesture called lip smacking.

(lip smacks) And they do it when they're kinda feeling nice and happy.

(typewriter types) (chatters) I scare my undergrads with that.

(laughs) (soft music) It all happened very innocently enough.

At our field sites, we spend lots of time here hanging around with monkeys in this beautiful place.

All of us are rolling around with cameras.

And I think either out of boredom or we just had some time or something, I started taking pictures of the monkey's hands and feet.

But it kind of just stuck.

It's something I found really visually interesting and just kind of a nice way to frame the fact that we are special but different.

And it sort of just a kind of different way to look at these creatures.

What started with kind of pictures of monkey hands and feet turned out to be pictures of lots of other animals' hands and feet.

I have pictures of blue-footed booby feet from the Galapagos, which are gorgeous because it's one of the only kind of very, very blue creatures out there.

And some of them have really wonderfully blue feet.

I have pictures of rhinoceros feet from a visit to a reserve in Africa.

(camera clicks) Tortoise feet from the giant Galapagos tortoises.

My favorite print is one of monkey's hands wrapped around a tree.

And it's a great shot because you can see kind of the monkey's hands and the fur and their fingernails.

And it really looks like human hands would look as wrapped around a tree.

I think my pictures of the feet are a little bit of a secret actually.

I was visiting my best friend this weekend and I mentioned the feet thing.

And she said, "I never knew you took pictures of these.

Like why do you take pictures of these?"

I think people might be worried about this.

They might kind of hide their feet away now that hey know I do this.

(soft music)