By Lisa A. Parr
We, as humans, get an enormous amount of information from faces. Just from a face we can tell who a person is, whether they are male or female, and what their mood is. And sometimes we can tell who their relatives are.
I wonder whether chimpanzees see faces as we do.
From our earlier experiments at Yerkes Primate Research Center, we knew that chimpanzees are very good at recognizing faces. Now we wondered if they could recognize whether chimpanzees were from the same family, such as a mother and a son.
But how do you ask a chimpanzee if they recognize
a mother and her child? It's a good challenge!
Chimpanzees are one of the most intelligent species of animal. In fact, they're so smart that we have taught them to play simple video games using a computer and joystick÷just like you would use at home.
I work with five chimpanzees: Scott, Katrina,
Jarred, Lamar, and Kengee. Each is about 10 years old. That's
about as old as a teenager in human terms. Over the last five years,
they have become really good at playing video games.
Because these chimps were good at video games, we set up a kin recognition experiment using a video-game approach. We wanted to text whether our chimps could correctly match a photo of a mother chimpanzee to a photo of her child, or offspring.
Playing the Game:
This is how it worked.
In the mother/son experiments, first the computer
showed a picture of an adult female chimpanzee, the mother. Then
the computer showed two more photographs: one was the son of the adult
female and the other was an unrelated chimp. To play the game, my
subjects used the joystick to move the cursor to the face that was the
most similar to the adult femaleās face.
Then we did the same experiment using photos of mothers and daughters.
The chimpanzees did very well in the mother/son tests. They correctly matched the mother with the son 76 percent of the time. However, we were surprised to find that the chimpanzees did much worse on the mother/daughter tests, averaging only 56 percent! How could this be?
To find out, we searched for clues by observing how chimpanzees live in the wild. Why would it be helpful for wild chimps to recognize relatives, especially male relatives?
Chimpanzees live in what primatologists (people who study primates) call a male-bonded society. This means that, for their entire lives, male chimpanzees live in the group in which they are born. Females, however, leave their birth group and find a new group to join.
Many males try to be the most dominant member of their group÷the big cheese! Males who have the most friends usually end up being the head of their group.
And usually the male friendships that last the longest are friendships with brothers. By being able to recognize brothers, chimps may help each other achieve better positions in the group. This way, success stays in the family.
Being able to recognize male relatives may help females, too. If a female joins a new group where the males look like her mother, they are probably related to her, like distant cousins. To avoid mating with her relatives, she might find another group to join.
These are some of the ideas we think could
explain why the chimpanzees in our study were so much better at recognizing
mothers and sons than recognizing mothers and daughters. But there
may be other reasons to explain the results.
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