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Chimpanzee Gaze

A series of papers has come out recently from the Primate Research Institute in Kyoto, Japan, using gaze-tracking technology to compare how chimpanzees and humans view photos and videos of both species—and whether there are any major differences in their patterns of viewing.

First, in a study by Kano & Tomonaga (2009a), chimpanzee subjects were presented with full-body images of chimpanzees, humans, and other mammals. Chimps viewed the face more than the body or limbs in each image, but human subjects looked significantly longer at faces than chimp subjects did. This study has shown that chimpanzees shift their gaze faster than humans do, and shift a greater distance across the presented image than humans. However, they tend to have longer fixations on the images.

Of key importance is how chimpanzees view faces, in particular, whether they pay more attention to the eye region than other regions, which is a common pattern in humans—humans gain a lot of semantic and emotional information from looking at others’ eyes. In a second study, Kano & Tomonaga (2009b), chimpanzee subjects were shown images of the faces of chimps and humans, with species-specific face expressions; each face was divided into areas of interest, such as eye, nose, mouth, and other. Humans consistently viewed the eye region, across species and expressions. Chimpanzees looked at the mouth area more than humans, and looked at the mouth more than the eyes in four of eight expressions. These results suggest species-specific strategies for facial communication.

In another study, Hirata et al. (2010), chimpanzee subjects were shown images of chimpanzee faces in either an upright or upside-down position, and with open or closed eyes. The chimps looked longest at the upright faces with open eyes, demonstrating that they process open and closed eyes differently. While chimps are sensitive to eyes, it may be that the eyes might not play as important a role in normal social interaction as in human interactions.

Not surprisingly, Hattori et al. (2010) showed that chimpanzees pay more attention to social cues given by images of conspecific models, rather than human models (human subjects paid equal attention to both chimp and human models). Using gaze-tracking, Hattori demonstrated that when the model looks or reaches to a target object (with an equivalent distractor object on the opposite side), the chimps looked longer at the target in every condition except when the human model looked, which suggests that chimpanzees gain more referential information from conspecific models.

Across studies, humans consistently pay most attention to the eyes, and it is interesting to note the unique morphology of human eyes compared to all other primates: humans have white sclera, and our eyes are horizontally elongated. Kobayashi and Kohshima (2001) studied and compared 88 species of primate eye, and suggest that pigmented sclera is an adaptation to hide gaze direction from others (including predators), and that highly visible human eyes are adapted to enhance gaze cues.

Tomasello et al. (2007) hypothesized that humans’ white sclera evolved to improve mutualistic cooperative and communicative interactions, such as joint attention and pointing. They compared how human infants and adult apes follow the gaze of a human model, who looked up to the ceiling with either his eyes only, head only, or both. Apes followed the model’s gaze more with the head cue, whereas human infants looked up most often when the model gazed using only his eyes. Tomasello writes, “Individuals in constant competition with onlookers should not evolve morphological characteristics to help these others follow their gaze direction.”
While head orientation cues may be more salient than eye-direction cues, Bethell et al. (2007) found that chimpanzee eye movement does have potential signal value to onlookers, and that gaze direction is often incongruent with head orientation, especially during different activities such as feeding, but not grooming.

It is slightly baffling that chimpanzees do look at the eyes in images of faces, but tend to have little success in recognizing attention, and fail at “guesser-knower” and object choice tasks that require the subject to use a human’s gaze cue to find hidden food (see Povinelli et al., 1990, Povinelli & Eddy, 1996, Reaux et al., 1999, Call et al., 1998, and others). However, this pattern makes sense when one considers that chimpanzee social cognition evolved in chimpanzee society, and may not generalize to interactions with humans; furthermore, chimpanzees tend to be more competitive, whereas humans are more cooperative, so it would be unusual for a chimpanzee to share information with a partner about the location of a hidden food, as was done (with a human model) in the failed object choice experiments (See Hare, 2001, Hare & Tomasello, 2004, Hare et al., 2000, Hare et al., 2001 for more on chimpanzees’ success in finding food in competitive conspecific paradigms).

With this improved understanding of chimpanzee ecology and behavior, along with the new data from the Primate Research Institute’s studies, it is important to realize that chimpanzees have different strategies for viewing faces and eyes than humans do, and to take this into account in designing future studies. Some interesting questions to address when comparing chimpanzee and human eyes include the evolutionary “cost” of sclera pigmentation, and whether chimps’ quick and broad scans with short fixations are a different adaptation for a similar purpose as humans’ elongated eye for horizontal scanning, which is presumed to be less energetically costly than a head turn. And, most importantly, what information can a chimp gain from a conspecific competitor’s gaze?

–Katie Hall

Missy Misleading

For my study on deception, I show Missy where a tasty banana is hidden in her outdoor enclosure; then I release her outside with an ignorant competitor, Rita. Today, Missy was not motivated at all to participate, and I was becoming frustrated since she does this often. I know from previous experience that working with Missy requires patience, and is worth the wait—she always does something clever to deceive Rita.

After nearly giving up my attempts to gain her attention, she finally watched as I placed the banana underneath a large red plastic ring. Once the video cameras were recording, my colleague Matt opened the door to release Rita, then Missy. Rita walked right past the hiding place to search in a hanging tire, where she had seen Missy find a treat back in November. Missy warily approached the red ring, and as she bent down to lift the ring for her reward, Rita turned around and brusquely marched towards Missy. Acting quickly, Missy sat down directly on top of the ring, preventing Rita from looking under it.

MissyMisleading

After a few moments, Missy walked off towards their climbing structure, making eye contact with Rita, who was following closely. Rita has learned over several months of testing that Missy has privileged knowledge about the banana. Rita, who is dominant to Missy, has developed a pattern of following her so that she may steal the banana from her.

Rita followed Missy onto the structure, but when Missy gave no further indication that she was searching for a hidden food, Rita climbed down and walked away. Missy then returned to the red ring, first checking that Rita was not watching her, and picked up the ring to find the banana. At that moment, Rita turned around to see she had been duped!

– Katie Hall, visiting student, University of St. Andrews

Spark Blog: Chimpanzee Culture?

Note: This blog was originally posted on the website of the Human Spark.

You can see all of the episode featuring the Living Links Center here.

Our Human Spark crew traveled to the Yerkes National Primate Research Center at Emory University to meet with the scientists – and the chimps! – who work there. Vicky Horner is a psychologist who explained to Alan Alda her work on chimpanzee cultural transmission. Here she shares some of her thoughts on her field of research and what it can tell us about the human spark.

by Vicky Horner, Living Links Center, Emory University

Vicky Horner and Alan Alda

Vicky Horner and Alan Alda

To many people, the words “culture” and “chimpanzee” don’t seem to go together. In fact, apart from starting with the same letter, they seem to have little connection at all. It’s therefore always slightly awkward when I have to explain what I do for a living to someone I don’t know very well. When I tell them that I am a psychologist, but that I work with chimpanzees and study their cultural behavior, I get the distinct impression that some folks think perhaps it is me, and not the chimps, that needs a psychologist!

The looks of surprise and confusion come from the fact that for many people the notion of culture equates with the fine arts, a night at the opera, or a refined palate for expensive wine. The idea of a chimpanzee at the opera sipping on a nice glass of chardonnay is pretty comical, even to me. We can all think of lots of examples of cultural differences between groups of people, but actually defining it in biological terms is a little more difficult. Psychologists, anthropologists and biologists have been arguing about culture for decades, and although we still don’t agree, we are getting a little closer to a definition that keeps most people happy. In order to understand culture, and more importantly to understand the evolution of our own cultural abilities, we need to stop getting caught up in examples of our cultural behavior and focus more on how cultural differences develop in the first place. At the fundamental level, culture is simply a collection of learned behaviors that have been passed on from one generation to the next, such as using chopsticks or knives and forks. For many years culture has been regarded as the hallmark of our species, the ‘human spark’ that separates us from other animals. However, before we can make claims about our own uniqueness, we need to check for similar sparks in other animals, starting with our closest living relatives, the chimpanzees, with whom we share a common ancestor and about 99 percent of our DNA.

A few years ago, a group of scientists working in Africa got together to compare the behavior of the chimpanzees at their field sites. What they found was rather surprising. At every site, the chimpanzees displayed a totally different pattern of behavior, such as how they use tools and weapons. These differences were not easily explained by differences in habitat or genetics. The scientists therefore thought that perhaps these differences represented chimpanzee cultures, and arose because each group had invented different solutions to similar problems (like dipping for ants with long sticks or short sticks), and that these behaviors were maintained over generations by learning from one another.

One of the Yerkes chimps uses a tool to extract a tasty treat from one of Vicky’s puzzle boxes.

One of the Yerkes chimps uses a tool to extract a tasty treat from one of Vicky’s puzzle boxes.

However, it is very difficult to study culture and learning in the forest because there are so many variables, so at the Living Links Center we study chimpanzee culture in a more controlled captive environment. We study two social groups of chimpanzees who live in large indoor-outdoor enclosures with climbing structures, grass and toys. We train one chimpanzee in each group to act as an “inventor” who solves a food puzzle (like how to get the banana out of the box with a stick) in one of two different ways. We then track if and how each new behavior spreads within the groups. These studies are important because they show us that chimpanzees have the brains for culture; they can learn and maintain new behaviors accurately enough to support the reports of culture from the wild. I am not claiming that there is no difference between going out to a Chinese restaurant to practice your chopstick skills and staying home to fish for termites in the back yard, but the fundamental psychological mechanism and the evolutionary driving force behind the two is the same.

Alan tries his hand at a puzzle box, though he’s not quite as motivated as a typical chimp to extract the M&M.

Alan tries his hand at a puzzle box, though he’s not quite as motivated as a typical chimp to extract the M&M.

So what does all this mean for the human spark? To me there is no single spark that separates us from chimpanzees; we are intricately connected by our common ancestry. The differences between us arise from thousands of tiny differences in the frequency and contexts in which we do things. For example, we imitate one another constantly; chimpanzees imitate each other sometimes. We take other people’s perspectives on situations frequently; chimpanzees take another’s perspective sometimes. We empathize frequently, they empathize in some contexts. It is all of these little tweaks here and there that make up the human spark.

On a final note, I’d like to emphasize the importance of not falling into the trap of thinking that we are the ultimate and desirable endpoint of evolution. Chimpanzees and humans have both been evolving form our common ancestor for the last 5 million years. They may not be at the opera, but chimpanzee culture is remarkable in comparison to other species. We also have a habit of measuring their abilities against our own human checklist in the quest for the human spark. But what would happen if we measured ourselves on a chimpanzee checklist; would we find a “chimpanzee spark”? How do you measure up to this five-year-old chimpanzee?

The Human Spark

The Human Spark, a PBS special hosted by Alan Alda, and featuring some of the chimpanzees from the Living Links Center will air this January. Check your local listings for broadcast times.

For more info, visit The Human Spark.

-Darby Proctor

Hominid: the Play

hominid

Theater Emory, together with Out of Hand Theater, recently translated “Chimpanzee Politics” into a play, written by Ken Weitzman. The play is entitled “Hominid,” which nowadays means the same as the old term Hominoid (I know this gets confusing!): A hominid is a member of the primate family that encompasses the great apes and humans. The play was directed by Ariel de Man, and featured actors Chris Kayser, Carolyn Cook, Adam Fristoe and Matt Huff.

The play takes the drama of the Arnhem chimpanzees, the power struggles, the chimp names, and many behavioral details and applies them to a human-like situation. One has to pay close attention to follow the storyline because there is little spoken language. One needs to read body language, which is a big difference with Shakespeare (with which the play is compared!) and other playwrights, who mostly rely on the spoken word to tell their story. Here we have strutting, hitting, food sharing, reconciling, and out-of-view sex scenes to convey who is dominant, subordinate, unhappy, attractive, and so on. At the end of the play, fragments of the movie “The Family of Chimps” are played to make the connections with chimp behavior explicit.

I found it a wonderful experience. The scene in the play where the chimps mourn the death of their beloved leader made me think of the photograph discussed on this blog. Seeing the play, one may wonder if chimps really care as much about the death of others as the actors make it seem, but the available evidence on chimp behavior make this scene seem less unlikely.

– Frans de Waal

Grieving Chimps

A photograph recently published by National Geographic and making the rounds online is renewing discussion about whether other animals experience the very human emotions of loss or mourning.

Photo credit: Monica Szczupider

The photograph by Monica Szczupider at the Sanaga-Yong Chimpanzee Rescue Center in Cameroon shows a group of chimpanzees (I counted 16) watching from behind a fence as Dorothy, one of their deceased members, is moved for burial. The composition of the photograph is remarkable. A large group of chimpanzees are gathered together in close quarters in a way that chimpanzees otherwise only do when sharing food or grooming. Each and every chimpanzee is focused on Dorothy, and you can even see chimpanzees in the back standing and craning to get a better look. A chimpanzee at the back left has his/her hand on another (physical contact is used for support in chimpanzees as well as people), a chimpanzee in the middle is leaning on someone in front, and on the right an older individual is holding her shoulders, basically giving herself a hug, which chimpanzees and humans use to comfort themselves. The serious, possibly even somber, expressions on the chimpanzees’ faces, combined with Ms. Szczupider’s description of how silent the chimpanzees were makes it very easy to translate this scenario into human terms. We, in this setting, would be grieving. Is it too much to suppose that the chimpanzees are doing the same?

The image immediately reminded me of a picture taken last year.

Photo credit: Marco Stepniak

A female gorilla named Gana at the Allwetter Zoo in Münster, Germany lost her 3-month-old infant to a severe infection. The gorilla carried the lifeless body for weeks before finally releasing it and allowing zookeepers to retrieve it. The photo is truly amazing. Gana peering at her lifeless son, we can only guess what she was thinking, but like many people faced with loss, she needed time to let go.

I am also reminded of a more personal experience. My family’s first dog was a wonderful golden retriever. When he died at age 11, we were all very upset, but within a week or two, we had another dog. None of us were ready to bond with a new pet, but we felt we had to, not for us, but for our other dog. Our 2-year-old German shepherd, a bundle of energy that challenged our ability to keep her stimulated, became sullen and lethargic after our golden retriever passed. She was depressed. So we decided, in her best interest, to adopt another dog. The adoption worked, and pretty quickly our shepherd returned to her normal self. With the help of two exuberant dogs, so did we.

The question is, how do we deal with animals seeming to experience some of the most profound of human emotions? Do we “anthropomorphize” and call this grief? Do we “anthropodeny” and call this something different, like withdrawal from the deprivation of contact with a socially significant other? Perhaps how we treat some other emotional responses will help clarify the problem. Scientists have no problem talking about stress in animals. The stress response, starting with perception in the brain and ending with the release of cortisol or a related hormone, is the same throughout mammals. Depression has a neurochemical signature that is similar for humans and other mammals. I’ve seen the same anti-depressants prescribed to people prescribed to primates and dogs for depression-like symptoms, and they’ve worked.

So what about grief? Essentially, grief is a stress response that leads to transient or chronic depression, based on the perceived loss of someone or something important. In this context, grief is a matter of perception. Do the chimpanzees and the gorilla in these photographs perceive the loss of these individuals? Are they affected emotionally? Looking at the faces in these photographs, I perceive nothing but grief.

– Matthew Campbell

Additional examples of animals responding to death can be found in Good Natured.

Our Kinder, Gentler Ancestors

Originally printed in the Wall Street Journal, Oct. 3 2009.

Ardi casts doubt on the notion that we have an innate killer instinct

By FRANS DE WAAL

Are humans hard-wired to be ruthlessly competitive or supportive of one another?

The behavior of our ape relatives, known as peaceful vegetarians, once bolstered the view that our actions could not be traced to an impulse to dominate. But in the late 1970s, when chimpanzees were discovered to hunt monkeys and kill each other, they became the poster boys for our violent origins and aggressive instinct.

‘Ardi’ Fossil Altering Ideas on Human Evolution

The skeleton of Ardipithecus ramidus, an ancient fossil dubbed “Ardi,” is radically changing our ideas about mankind’s origins. Kent State University’s C. Owen Lovejoy says Ardi shows our ancestors were more like us and less like chimps. WSJ’s Robert Lee Hotz reports.

I use the term “boys” on purpose because the theory was all about males without much attention to the females of the species, who just tagged along evolutionarily. It was hard to escape the notion that we are essentially “killer apes” destined to wage war forever.

Doubts about this macho origin myth have been on the rise, however, culminating in the announcement this past week of the discovery of a fossil of a 4.4 million year old ancestor that may have been gentler than previously thought. Considered close to the last common ancestor of apes and humans, this ancestral type, named Ardipithecus ramidus (or “Ardi”), had a less protruding mouth equipped with considerably smaller, blunter canine teeth than the chimpanzee’s impressive fangs. This ape’s canines serve as deadly knives, capable of slashing open an enemy’s face and skin, causing either a quick death through blood loss or a slow one through festering infections. Wild chimps have been observed to use this weaponry to lethal effect in territorial combat. But the aggressiveness of chimpanzees obviously loses some of its significance if our ancestors were built quite differently. What if chimps are outliers in an otherwise relatively peaceful lineage?

Consider our other close relatives: gorillas and bonobos. Gorillas are known as gentle giants with a close-knit family life: they rarely kill. Even more striking is the bonobo, which is just as genetically close to us as the chimp. No bonobo has ever been observed to eliminate its own kind, neither in the wild nor in captivity. This slightly built, elegant ape seems to enjoy love and peace to a degree that would put any Woodstock veteran to shame. Bonobos have sometimes been presented as a delightful yet irrelevant side branch of our family tree, but what if they are more representative of our primate background than the blustering chimpanzee?

The assumption that we are born killers has been challenged from an entirely different angle by paleontologists asserting that the evidence for warfare does not go back much further than the agricultural revolution, about 15,000 years ago. No evidence for large-scale conflict, such as mass graves with embedded weapons, have been found from before this time. Even the walls of Jericho—considered one of the first signs of warfare and famous for having come tumbling down in the Old Testament—may have served mainly as protection against mudflows. There are even suggestions that before this time, about 70,000 years ago, our lineage was at the edge of extinction, living in scattered small bands with a global population of just a couple of thousand. These are hardly the sort of conditions that promote continuous warfare.

The once-popular killer ape theory is crumbling under its own lack of evidence, with “Ardi” putting the last nail in its coffin. On the other side of the equation, the one concerning our prosocial tendencies, the move has been towards increasing evidence for humans as cooperative and empathic. Some of this evidence comes from the new field of behavioral economics with studies showing that people do not always adhere to the profit principle. We care about fairness and justice and sometimes let these concerns override the desire to make as much money as possible. All over the world, people have played the “ultimatum game,” in which one party is asked to react to the division of benefits proposed by another. Even people who have never heard of the French enlightenment and its call for égalité refuse to play along if the split seems unfair. They may accept a split of 60 for the proposer and 40 for themselves, but not a 80 to 20 split. They thus forgo income that they could have taken, which is something no rational being should ever do. A small income trumps no income at all.

Similarly, if one gives two monkeys hugely different rewards for the same task, the one who gets the short end of the stick refuses to cooperate. We hold out a piece of cucumber, which normally entices any monkey to perform, but with its neighbor munching on grapes cucumber is simply not good enough anymore. They protest the situation, sometimes even flinging those measly cucumber slices away, showing that even monkeys compare what they get with what others are getting.

And then there is the evidence for helping behavior, such as the consolation of distressed group members, which primates do by means of embracing and kissing. Elephants give reassuring rumbles to distressed youngsters, dolphins lift sick individuals to the surface where they can breathe, and almost every dog owner has stories of concerned reactions by their pets. In Roseville, Calif., a black Labrador jumped in front of his friend, a six-year-old boy, who was being threatened by a rattle snake. The dog took so much venom that he required blood transfusions to be saved.

The empathy literature on animals is growing fast, and is no longer restricted to such anecdotes. There are now systematic studies, and even experiments that show that we are not the only caring species. At the same time, we are getting used to findings of remarkable human empathy, such as those by neuroscientists that reward centers in the brain light up when we give to charity (hence the saying that “doing good feels good”) or that seeing another in pain activates the same brain areas as when we are in pain ourselves. Obviously, we are hard-wired to be in tune with the emotions of others, a capacity that evolution should never have favored if exploitation of others were all that mattered.

Frans de Waal, a professor of primate behavior in the psychology department at Emory University, is the author of “The Age of Empathy.”

Amy Pollick featured in documentary

Dr. Amy Pollick, a graduate of the Living Links Center is featured in the documentary “On the Road with Homo sapiens.” She discusses gestural communication in chimpanzees.

View the clip below.

– Darby Proctor

Chimpanzees negotiate towards cooperation

Cooperation in animals is nothing new. Darwin mentioned it frequently. We know honeybees cooperate with kin to protect the colony, lions cooperate to take down a gazelle on the African savannah, chimpanzee males go on group border patrols in the African jungle, and humans often help move a disabled car off to the side of a busy highway. Cooperation, then, is quite common across the animal kingdom. New research, however, is beginning to show that, in its most complex forms, some animals may actually have more than just a simple understanding of how cooperation works.

In a study that dates back more than 70 years, chimpanzees learned to pull in a heavy box together to get the food that was placed on top of the box. More recent studies with capuchin monkeys that used a similar apparatus showed that capuchin monkeys will wait for the arrival of a partner before pulling, seemingly realizing that the drawer isn’t going to move without a friend’s help. A more recent study led by Japanese scientist Hirata used a novel task that required two chimpanzees to simultaneously pull two ends of the same rope to get food (see the picture below – a single rope is fed through a tube and two platforms, so that BOTH ends of the rope must be pulled together for the entire apparatus to move). Here too the chimpanzees learned to wait for a friend to arrive at the other end of the rope, pick it up, and pull before pulling the rope themselves. Clearly, these chimpanzees realized that they needed a partner to complete the task (i.e., obtain the food rewards).

A study by Melis, Hare and Tomasello looked even further into a chimpanzees’ understanding of cooperation. Chimpanzees not only learned to coordinate their pulls to pull in a platform, but learned to PICK partners that were better pullers; in other words, chimpanzees chose to “play the cooperation game” with better collaborators (in these experiments, the chimps could pull a door pin to allow one of two chimpanzees into the room with them). In this cooperation task, chimpanzees demonstrated not only that they understood they needed a partner, but seemingly that some partners were better than others.

Now there is a new study by the same team in which two of the same type of rope-pull drawers were provided to two chimpanzees (the same chimpanzees from the previous studies who already understand how the task worked). Individuals compete for unequal resources, and sometimes need to negotiate over these resources so that both parties can successfully claim a reward. This study attempted to demonstrate how such negotiations lead to cooperation.

One drawer had equal amounts of food on both ends, while the other had unequal amounts (such that one plate was full of food, while the other had even less than the other drawer). Only ONE drawer could be chosen in each trial, and thus, the chimpanzees had to decide which drawer they would pull in together. Predictably, the first individual into the testing room, the dominant chimp, chose to sit in front of the biggest plate. But often, when the subordinate chimp entered the room, he refused to sit in front of the smallest food plate, instead opting to wait patiently in front of the “equal” drawer. Such behavior demonstrates that the chimpanzees seem to have realized that by simply agreeing to the dominant chimpanzee’s initial offer, the ultimate reward would be significantly less than if they “negotiated” for an equal reward.

In many of these tests, the chimps successfully pulled in the drawer. How? Well, although sometimes the dominant chimpanzee was quite stubborn and refused to give up his large reward, often, the dominant individual realized that unless he sat in front of the “equal” drawer and pulled with the other chimpanzee, he wouldn’t get any reward at all. In this way, the chimpanzees learned to “negotiate” for cooperation. The only non-primate species to be tested in this type of cooperation task, rooks of the corvid family, succeeded in pulling in a drawer together but failed to wait for partners if released into the testing room individually. Are primates, then, the only group of animals able to understand cooperation on a more complex level? Only further research on a wide-range of species will provide an answer.

–Josh Plotnik

The Power of Mimicry

Mirror neurons, first discovered at the University of Parma in pigtail macaques, are seen as the key to a lot of interpersonal interactions ranging from imitation to empathy. These neurons erase the distinction between one’s own and somebody else’s behavior. Mirror neurons respond the same when a monkey itself is reaching for a peanut as when it sees another reach for a peanut. This is why they are also known as “monkey-see, monkey-do” neurons.

Their discovery has been hailed by Vilayanur Ramachandran: “I predict that mirror neurons will do for psychology what DNA did for biology: they will provide a unifying framework and help explain a host of mental abilities that have hitherto remained mysterious and inaccessible to experiments.”

Everyone assumes that humans have the same mirror neurons (even though until recently the evidence for this was not overwhelming), which explains why we easily adopt someone else’s facial expressions (we smile when others smile, yawn when others yawn, etc.), and why we like it when others mimic our own movements. We like to walk in stride with others and emphasize synchrony, for example, when we dance. Studies have shown that if a man or woman goes on a date with someone who mimics their movements (leans on table when we do, picks up glass when we do), we rate the date as more attractive than one who is friendly but unsynchronized with us.


Bodily synchrony is very in common animals, because many animals live in herds, flocks, or groups where it is very important to move together and be highly coordinated. The same tendency is visible in human-animal interactions. See for example the picture of the dog and Chinese soldier – this kind of synchronization would be impossible if the dog had no way of mapping its own body onto another’s – or watch the remarkable video of synchronized movement between a woman and her dog, Tina Humphrey and Chandi.

Now there is finally a study of the same love of mimicry in monkeys, following the rule that the best ideas for animal studies often come from comparisons with human behavior (something about which I blogged recently). Annika Paukner and colleagues presented brown capuchin monkeys with experimenters who either acted exactly like the monkeys or showed no such mimicry. They then measured whom the monkeys preferred to interact with. The monkeys preferred the mimicking person, which means that a) they noticed when people copied their actions, and b) they preferred such people over others, just as had been shown earlier in human studies.

The power of mimicry in social relations is going to be a major theme in future animal studies. We are working on it here at Living Links, and so are other teams, and we can be sure that neuroscience will increasingly be part of the picture.

– Frans de Waal

 

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