“So Human, So Chimp” premieres January 13 on PBS.

A resident of Cayo Santiago takes in the scene. Photo by Larry Engel

By Larry Engel, Director of Photography

At the southeastern tip of Puerto Rico is a small island only a short boat ride from the mainland. We flew into San Juan, drove south through the mountains, down to the shore to meet the scientists with whom we would work the following morning. At the beach, families were enjoying the late afternoon sun and water. People were dancing in the parking lot. It was warm and pleasant. We could see Cayo Santiago about a half-mile offshore from the pier.

The island is home to a group of monkeys that were brought there in 1938 so North American researchers could better study primates without having to go to South America or Africa. One problem, though, was that in the early days of primate research, people didn’t have a solid grasp of habitat and dietary needs for their research animals. Even though it seemed as if Cayo Santiago was big enough to support a colony of rhesus macaques, it turns out that the vegetation and habitat area is not sufficient to support the 1,000 monkeys who currently live freely on the island. So there is a need to supplement that food, which does grow on the island, and two main feeding stations provide extra food for the monkeys. To get to the food, the monkeys have to open metal bins. The lids clang off-and-on throughout the day, and while we were filming this sound drove me nuts. An otherwise peaceful setting was constantly dotted with the clinging and clanging of what sounded like, at least to me, crazy garbage men at work.

We were warned that the monkeys could come over and try to bite us, but that we could fend them off with our own loud noises and a few displays of aggressiveness (for example, raising our arms high and waving them — sort of like what you might do if you were trying to get rescued). I thought that the camera would be a good defense, so I wasn’t too worried. But a couple of times during the day’s shoot, one of researchers would yell out a warning to the monkeys while I had my eye to the viewfinder.

We were also warned not to spend too much time under branches where monkeys were sitting. This was a somewhat difficult task for me as I would find a good location for a shot but then realize that I had positioned the tripod or myself directly beneath a monkey. The reason that you don’t want to hang out under a monkey on a branch is that they have a tendency to intentionally urinate on you – or worse! I wondered if I should put the rain cover on the camera but decided against it. We all paid close attention to what was going on above us throughout the day.

In order to get on the island we had to have tuberculosis tests and provide our negative results. This was to protect the monkeys, not us. Throughout the primate world, there is growing alarm over the transmission of human diseases to our cousins. They don’t have the exposure to our diseases, and that makes them susceptible to not only getting sick but dying from illnesses that are seemingly innocuous to us – like the common cold. Another precaution: we had to retreat to a caged hut to eat and drink. We couldn’t eat anything outdoors; it would be bad for both the monkeys and us. I liked the idea that we were the ones who had to be inside the cage looking out while the monkeys were on the outside looking in.

A monkey makes his approach toward the grape of the researcher with her back turned, presumably because it thinks it will be easier to steal from someone who isn’t looking. Photo by Larry Engel

We were there to film researcher Laurie Santos and her experiments that look at monkeys’ decision-making concerning thievery. We were hoping to capture it all on video – not an easy task with our additional crew members in attendance.

This monkey successfully snagged the grape from behind Laurie Santos’ back. Photo by Larry Engel

The way it works is that two people approach a monkey who is paying attention to them. They both do exactly the same thing: show the monkey a grape, put it onto a square piece of wood, and put the “plate” on the ground. A third person counts and calls out the moves so that each person does exactly the same thing at the same time. When the grapes are on the ground, one person turns her back to the monkey. The other person stays facing the monkey. Then, both are motionless. The monkey more often than not sneaks up on the person who is not looking and steals the grape.

We actually were able to film the experiment successfully and even photographed another one. It was amazing how fast the monkeys would make their decision to go for the grape… but each monkey would look up at the experimenter’s back all the way to the grape before hightailing it back to the bush with treat in hand. One monkey, however, didn’t really care who was aware or unaware of his action. It appears that he was a dominant male and really didn’t care who he took food from. He was, literally, king of the hill.

I really enjoy filming animals, especially primates. When I’m looking into the eyepiece, through the lens, most of my world disappears and I’m in their world. I don’t see us; I see them. I’m drawn into their world, I look into their eyes, and I wonder what they are thinking about me. Do they look at us and think that we look somewhat like them? Do they wonder what we’re thinking as I do about them? There is a connection, but also a divide. And I’m honored to film among researchers who are trying to bridge it so that we can understand them better and, ultimately, they us.

In this video, Laurie pulls a sleight-of-hand switcheroo on her monkey research subjects. Will they notice when a fruit that starts rolling down a plank as a kiwi reaches the bottom as a lime? Watch to see how the monkeys react… and find out what this study implies about their abilities – and ours.

For more info, check out this article about Laurie and her monkey research from Discover Magazine: “The ‘Monkey Whisperer’ Learns the Secrets of Primate Economics”

Stubtailed macaques

Of course monkeys don’t speak to each other in elaborate paragraphs, but they do communicate by vocalizing. Researchers turn to monkeys in an effort to understand some of the most basic foundations of human communication. The idea is that other primates have rudimentary systems that eventually evolved further in human beings to support spoken language.

A new study looked at how macaque monkeys respond to other monkeys’ efforts at communication in the form of drumming or vocalizing. Researchers found that monkeys reacted to both the same way, not just behaviorally but also neurally. Hearing drumming or vocalizations activated overlapping networks in the monkeys’ temporal lobes. To the scientists, this finding suggests a common origin for vocal and nonvocal communication systems. The study lends some support to the idea that language and music evolved side by side in humans.

Does the theory that human speech and language evolved from gestures and rhythmic music make sense to you?

More information:

• Proceedings of the National Academy of Sciences of the United States of America research article: “Monkey drumming reveals common networks for perceiving vocal and nonvocal communication sounds“
• LiveScience article: “Monkey Drumming Suggests the Origin of Music“

Researcher Kerry Jordan shared her thoughts with us:

“What makes us unique as humans in the domain of mathematics is our use of an exact counting system that depends on language.  Symbolic number systems are so important to human thought that most cultures all around the world have developed them.  This is despite the fact that we share a primitive number system with animals – from birds to mammals – which already allows us to estimate quantities without using language.”

Read the full article here.

Video credit: Elizabeth Brannon and Kerry Jordan of Duke University