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Chimps R Us


Photo Bjorklund

David F. Bjorklund is a Professor of Psychology at Florida Atlantic University, where he has taught graduate and undergraduate courses in developmental psychology since 1976. He received a B.A. degree in Psychology from the University of Massachusetts in 1971, an MA degree in Psychology from the University of Dayton in 1973, and a Ph.D. degree in Developmental Psychology from the University of North Carolina at Chapel Hill in 1976.

His current research interests include children's memory and strategy development, cognitive developmental primatology, and evolutionary developmental psychology.

He has received numerous teaching awards from Florida Atlantic University, and he is the author of several books, including the forthcoming The Emergence of Evolutionary Developmental Psychology with Anthony Pellegrini.

Bjorklund currently serves as Associate Editor of Child Development, published by the Society for Research in Child Development, and has served on the editorial boards of several professional journals and as a contributing editor to Parents Magazine. He has published over 90 scholarly articles on various topics relating to child development, focusing primarily on memory development.


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Bjorklund responds :

4.23.01 Chris Rushlau asked:
Do chimps have imaginations?

Bjorklund 's response:
In a sense, yes. People who work with chimpanzees in captivity are often amazed at the sort of clever things they see chimps do. For example, one of the chimps at our sanctuary, Grub, loves to make paper masks out of strips of cardboard. After he carefully tears two eyeholes in the paper, he will then hand the masks to his human caretakers to don while they chase him around his enclosure playing tag! But this might not demonstrate imagination, per se, because it's not entirely clear what Grub is thinking when he's doing this. (It might only be a sort of ritual that he's associated with having fun, and something that his caretakers have encouraged.) Imagination requires the ability to cognitively combine conceptual elements that do not normally appear together - such as when 4-year-olds treat a banana like a telephone - and it isn't clear whether chimpanzees are able to do this on their own.

4.23.01 monkeyguy asked:
I have worked with and studied New World monkeys for the last 10 years. I have 2 questions for you; do capuchin monkeys actually know it is their reflection in a mirror? Will a male capuchin always try to win dominance throughout his entire life? Or does it have the intelligence to realize that he's not strong or big enough to win the throne?

Bjorklund 's response:
Mirror recognition has been used as a sign of self-awareness. Monkeys exposed to mirrors certainly look in them and seem to find them fascinating, but this alone does not imply self-recognition. To test for self-recognition, scientists use the "mark test" in which a mark is placed on an animal's forehead, without them knowing it. Now when animals look in the mirror, will they realize that the image they see with the strange mark on the forehead is them? If they do, they will touch their own foreheads. If they do not, they will touch the mirror. Human children beginning about 18-months of age "pass" this test (that is, touch their foreheads), as do chimpanzees and orangutans, but at an older age. Most gorillas seem not to understand that they are looking at themselves in the mirror, and, to my knowledge, no monkey, even the very bright capuchin, "pass" this test. So, to come to the point, it is likely that capuchin monkeys who see themselves in the mirror to do not know that they are looking at their reflection.

Concerning your second question, you, with your 10-years experience working with capuchins, would actually be in a better position to answer that than I. Older chimpanzees, after losing battles with younger and stronger chimpanzees for dominance, will often "take their place" as a lower ranking members of the troop. I would think that, in the wild, capuchins show similar behavior.

4.23.01 Susan Hammer asked:
1. Do chimps go into estrus? Is the swelling what was observed?

2. Are chimps or the great ape the closest relative to Homo sapiens?

Bjorklund 's response:
Dear Susan, Yes, female chimpanzees do go into estrus, and, you're right, the swelling on their bottoms is the sign to the males that are in estrus.

Concerning who are humans' closest relatives, it seems that it is a tie. There are two separate species of chimpanzees: common chimpanzees (Pan troglodytes) and bonobos, sometimes called pygmy chimpanzees (Pan paniscus). All of the chimps that you saw on the TV show were common chimpanzees. Both species of chimpanzees are equally related to humans, sharing approximately 98% of their DNA with us. The other great apes include gorillas, who share a bit less of their DNA with humans, and orangutans, who share less DNA still, but more than any monkey.

4.23.01 T. Laurel Marburg asked:
Dr. Bjorklund, Hello, I am a Biology and Psychology major at Virginia Tech with a main aim to study animal behavior, specifically communication among mountain gorillas. I have two questions for you. First, how did you acquire all the chimps you study? And second, have you ever studied the language development in primates?

Bjorklund 's response:
I have been fortunate enough to work at the Center for Orangutan and Chimpanzee Conservation, an ape sanctuary currently located in Wauchula, Florida. The Center was originally housed on the grounds of Parrot Jungle in Miami, and it was there where I first worked with the chimpanzees and orangutans. Presently, there are six chimpanzees and two orangutans at the Center. All had either been raised as pets or in the entertainment industry, and most came to the center as infants. The Center provides a relatively spacious and humane environment for these animals. The Director, Patti Ragan, permits us only to do research with the apes if she thinks the experience will serve as an enrichment for them. So you see, this is not a standard laboratory situation, but one in which the animals' needs come first. You may want to visit the Center's web site at:

And to your second question, I have never done any research with language development in apes. Two of the chimpanzees at the Center have been taught some signs and use them to communicate with their human caretakers, but there is no "language training" program going on at the Center as there is in other places, such as Yerkes labs in Atlanta.

4.23.01 Chad asked:
When you did the experiment with the blackbird as a screwdriver and the hawk as sandpaper, why didn't you give the chimps the blackbird and the hawk to see if they used them as the humans did as sandpaper and screwdriver when the chimps picked them?

Bjorklund 's response:
That's a great question! While it would seem as if handing the objects directly to the apes after seeing the experimenters' treatments makes sense, there were a number of logistical problems that we had to face that prevented us from doing so. Most important of these was the fact that the taxidermy specimens we used for the 'animate' object category were relatively fragile, and if you've ever seen footage of a wild chimp who has just captured a colobus monkey, you'd see why it would not have been wise to let the apes handle the objects. Also, we were concerned that the chimps might learn, after handling the objects themselves, that there was nothing truly unique about them; we could therefore only determine if the experimenters' actions violated the chimpanzees' expectations by using the visual preference paradigm.

4.23.01 Ankit Vachher asked:
In the segment "Chimps Nations", I saw that the chimps put their hands up in the air and groom. What is the reason behind this? Why do the chimps groom?

Bjorklund 's response:
Lets start with your second question first, "why do chimps groom?" There are at least two reasons for this. One, is that grooming serves to rid the chimps of parasites, and it is difficult for them, or anyone, to pick small bugs off parts of your body that you cannot see, making grooming by others very practical. But grooming also plays a social role. Grooming is a way of communicating, making friends, firming up social relations, and making up after fights. Chimpanzees are a very social species, and grooming is one technique in which they relate socially.

As to why they put their hands up in the air, your guess is as good as mine. Although all chimpanzee groups groom, only a few put their hands up in the air while they do so. This suggests that this form of grooming is not something that is "in the genes," but rather is a tradition that was developed in some groups but not others and is passed along to juveniles in the troop. You can think of this as similar to different forms of greetings among humans. In Japan, for example, a bow is appropriate, while in the West we shake hands. Bowing versus hand shaking reflects differences in culture, and similar claims have been made for chimpanzees.

4.23.01 Kristal asked:
Are the lab environments where your chimps live appropriate for their needs? Some of the labs such as Alamogordo, NM, Coulston labs are hellholes for chimps. What can we do?

Bjorklund 's response:
We certainly believe that no captive environment for chimpanzees can compare to their natural environment in the wild. Because the species is best adapted to the ecological and social conditions under which it evolved, highly artificial environments, such as laboratories or poor zoological housing, can lead to a variety of heartrending abnormal behaviors. Fortunately, most zoos, and even today's labs, recognize the psychological complexity of chimpanzees, and are committed to making sure that their lives are as enriching as possible under the unavoidable circumstances of captivity. Most modern facilities, for instance, house chimpanzees together rather than alone, and provide their charges with materials and artifacts, structural supports, and vegetation - things that are critical for apes' contentedness. At the Center for Orangutan and Chimpanzee Conservation, our first priority is the psychological and physical wellbeing of our animals - research is only our secondary concern. After all, psychological testing on impoverished animals can lead to findings that do not necessarily reflect the species in general. For more information on chimpanzee sanctuaries in the US, or how you can help apes in need, visit our web site at

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