Is males' attraction to trucks and balls genetically based?

 Young chimps. Photo: Delphine Bruyere 

My husband and I raised one girl and one boy, close together in age. We tried hard to avoid gender-stereotyping our young kids in any way. They had the same toys, many of them gender neutral, for some time.

Our son clung to the baseball fence, drooling
As it happened, our yard backed up to a school athletic field. From late winter on, we daily heard the THWOCK of  bats hitting balls during baseball practice. Our son was barely able to walk when he began toddling out to the playing field alone, to watch the students play baseball.  He'd hang on the baseball fence with his tiny fingers for hours, mesmerized and drooling. Soon he was into trucks - at the age of 2, he memorized the name of 33 different kinds of trucks from the truck library books he clamored for.  Our daughter's interests were varied, but she showed no inkling of his fascination with balls and trucks. We couldn't understand it. He wasn't in preschool, and my husband and I cared nothing for vehicles of any kind (although Ken is a baseball fan).

We share 98% of our DNA with chimps
So last week I was intrigued to see a paper in the online journal Current Biology about gender-stereotyped roles in young chimps. Since chimps are our closest relatives, sharing 98% of our DNA, any observations about chimp behavior could have implications for the origins of our own behavior.
 

Young female chimps "play mothering" more than young males

Author Sonya Kahlenberg, a biological anthropologist at Bates College in Maine, observed chimps in Kibale National Park in Uganda over 14 years. She and co-author Richard Wrangham, a biological anthropologist at Harvard, noted that 67% of young females carried sticks while only 31% of young males did. Sticks are used sometimes as weapons or as tools, to probe holes for food or water. But the young chimps also cradled long thick sticks as if a stick were a baby, carrying it around for no particular reason. They sometimes carried the stick as long as 4 hours, and took it with them to their nests for sleep. The authors felt that the stick-carrying was "play-mothering." The males who did it stopped as they got older. The females stopped when they gave birth to real babies, whereas use of sticks for other purposes continued after motherhood.

In her recent article, Kahlenberg cited previous research in which captive young male monkeys preferred wheeled toys, while female monkeys, like human girls, showed greater variability in preferences. The male monkeys also showed more rough-and-tumble play than females. The authors of this study (published in PubMed) hypothesized that these differences are hormonally influenced.

Some have speculated that boys, including some male primates, prefer toys like balls and trucks because these toys are associated with more freedom of movement than, for example, playing with dolls.

Evolutionary advantage for human males to prefer movement?
Could it be true that very young male humans are drawn to balls and trucks because playing with them involves more movement?  It's not clear at all to me that male attraction to movement would be more advantageous evolutionarily than female attraction to movement. Even while carrying infants, our female prehistoric ancestors still were compelled to move around gathering plants for food, I would think. And keeping up with mobile children certainly involves movement. But if males were the defenders of early human tribes, and if they went on long hunts for food, then perhaps males could have evolved a hormone-based propensity to be more active.

I don't know, it's an interesting question. Culture has so much to do with it. A few decades ago, girls rarely if ever participated in team sports at school (at least in the U.S.). Today they do, when given the opportunity.

One more reason to protect wild apes
I'd love to see more field observations of gender-based behavioral differences in young primates. That's one more reason we need to protect chimpanzees and other primates from the illegal poaching that threatens all populations of wild apes.

For more information about what you can do to protect wild apes, see these links to primate conservation NGOs:
Jane Goodall Institute
Orangutan Outreach
Sumatran Orangutan Society
Dian Fossey Gorilla Fund International
Orangutan Land Trust
International Primate Protection League
TRAFFIC:the wildlife trade monitoring network

Some of my previous posts about primates and primate conservation:
Hunting may threaten orangutans even more than habitat loss Dec 6, 2010

Wildlife trade rivals drug trade in profits September 20, 2010
Laws flaunted: flourishing pet trade threatens orangutans' survival August 23, 2010
My search for a wild orangutan in Borneo and Sumatra August 16, 2010
Orangutans dwindle as Borneo, Sumatra converted to palm-oil plantations August 3, 2010

The great apes are losing ground. March, 2010
The U.S. imports 20,000 primates per year. February, 2010
Baboons are Africa's most widespread primate. Females rule! December 30, 2009
Mama monkeys give in to tantrums....when others are watching. April 23, 2009
Angry chimp reveals a "uniquely human" ability. March 21, 2009

Monkeys and parrots pouring from the jungle. September, 2008
Chimps' short-term memory is better than humans'  April 2, 2008
Chimps share human trait of altruism August 3, 2007

Keywords: chimpanzees chimp behavior animal behavior gender stereotypes chimps and dolls chimps and sticks Sonya Kahlenberg Kibale National Park Richard Wrangham

Angry chimp reveals a "uniquely-human" ability

Santino the chimp, photo courtesy of www.telegraph.co.uk

Santino the angry chimp is famous. You can google his name and find dozens of stories about him, in science journals and popular media.

It's not his anger that's making him famous, but how he plans ahead for his fits of rage.

Santino, a 30-year-old resident of the Furuvik Zoo in Sweden, has been observed collecting and stockpiling stones in his enclosure to use as future weapons. Later, when zoo visitors get on his nerves in a big way, he grabs stones from his cache to hurl at the annoying voyeurs!

He has also been observed tapping the concrete rocks in his enclosure to identify the weak parts, then dislodging a piece. If the chunk is too big to throw, he breaks it into smaller pieces.

The newsworthy part of this story is not that Santino makes tools; we have abundant documentation of primates and birds making tools, mostly as food-gathering implements.

The remarkable feature here is that Santino is planning for his future outbursts of temper.

Planning is a cognitive ability generally attributed only to humans. Or at least, we have little verifiable evidence of planning in non-human animals.

You might say that a squirrel's stashing nuts for winter is evidence of planning, but it's not necessarily. It's more likely that squirrels instinctively stash nuts as day length begins to shorten, since young squirrels who have never experienced a winter still do it.

True planning shows that an animal is considering what its future feelings will be at a later time.

As it turns out, Santino, as the dominant chimp at the zoo, has been storing and heaving stones over the moat at visitors for at least 11 years. Zookeepers have found and removed hundreds of Santino's caches of stones over the years. Fortunately for visitors, chimps throw underhanded and have terrible aim, so no one has been seriously injured by these "hailstorms" of aggression. And the stones are directed only at zoo visitors, never at the other chimps.

Scientist Mathias Osvath of Lund University says "These observations convincingly show that our fellow apes do consider the future in a very complex way. It implies that they have a highly developed consciousness, including lifelike mental simulations of potential events.....he first realizes that he can make these and then plans on how to use them. This is more complex than what has been showed before."

For me, Sally, it means that once again we have evidence that humans are not so unique after all. And so, I believe we should stop hogging the world's land and resources for ourselves, and stop fouling the remaining green spaces and waterways with our effluvia. We do not deserve dominion over the scraps of wild habitat and resources that remain.

Santino the chimp with stone in hand, photo courtesy of www.cbc.ca

Keywords:: chimps chimpanzees animal intelligence planning in animals Santino the chimp

Exciting New Discovery: Chimps' Short -Term Memory Is Better than Humans' (see video)

Dr. Matsuzawa with smart chimps Ai and Ai's son Ayuma

I have mixed feelings about keeping chimps in captivity. As I've written about before, chimps in medical or pharmaceutical labs often lead miserable lives.

But keeping chimps in captivity, when all their needs are met, has some benefits. For one thing, sustaining healthy breeding populations in zoos can help to ensure their survival. Most wild populations of chimps are threatened by habitat loss, by the illegal trade in wildlife, and by being hunted for "bushmeat."

Another benefit to humane captivity, in a stimulating and social environment, is that behavioral researchers can broaden our understanding of just how smart chimps are, and how many traits they share with humans. Chimps are, after all, our closest living relatives, genetically and evolutionarily.

I was very excited to see recent chimp research from Kyoto University that demonstrates chimps are actually better than humans at some types of short-term memory.

I worked with chimps for a couple of years in my early days of grad school, with Dr. Roger Fouts at the U. of Oklahoma. He was one of the pioneers in teaching chimps to use American Sign Language. Their capacity for language has been well established by a number of researchers now.

But the memory test in Kyoto is a new thing. It's the first demonstration I've seen that chimps can surpass humans at a cognitive skill.

This new test is a Concentration-like game using numbers on a computer screen.

“We were very surprised to find this,” said Tetsuro Matsuzawa of the Primate Research Institute at Kyoto University. “But it’s a very concrete, simple fact. Young chimps are superior to human adults in a memory task.”

Dr. Matsuzawa and a c0-worker, Sana Inoue, began by training chimps to recognize the numbers 1 through 9 in order. Ai, an adult female who was the first chimp trained, performed as well as adult humans.

But when the researchers tested chimps younger than 6, the primates had a touch screen where scattered numbers appeared for up to two-thirds of a second and were then covered by white squares. After the shortest exposure time, about a fifth of a second, the young chimps had an 80 percent accuracy rate at tapping the numbers in their proper sequence, even though they could no longer see the numbers. This was far superior to adult humans’ accuracy rate of only 40 percent. The findings are described in Current Biology.

A human subject selecting the wrong white squares

Dr. Matsuzawa said the chimps' ability might be similar to a "photographic memory," which is seen rarely in human children.

But however they do it, it's certain that "young chimpanzees have a better memory than human adults," asserted Dr Matsuzawa. "We are still underestimating the intellectual capability of chimpanzees, our evolutionary neighbors."

Dr. Lisa Parr, who works with chimps at the Yerkes Primate Center at Emory University, described the Kyoto research as "ground-breaking". She said it's importance is unparalleled. "They are our closest living relatives and thus are in a unique position to inform us about our evolutionary heritage," said Dr. Parr.

She concluded that these elaborate short-term memory skills may have been shared by a common ancestor of chimps and humans, but may have lost their importance in humans as we grew increasingly reliant on language-based memory skills.

A young chimp, before the numbers are covered (see this video on youtube)

How fast can you count the numbers? Take the test and see.

What's more important to me than learning about our evolutionary connections is learning how valuable these animals are to us right here and now. How can we eat animals that are as intelligent in some ways as we are? Surely this is motivation to protect the world's dwindling populations of chimpanzees more effectively than we are now.

If you want to learn more about protecting populations of wild chimpanzees, see Jane Goodall's website.

Sources:

Henry Fountain. Dec 4, 2007. NY Times. "Chimps Exhibit Superior Memory, Outshining Humans." http://www.nytimes.com/2007/12/04/science/04obchim.html

Helen Briggs. BBC News. Chimps beat humans in memory test. http://news.bbc.co.uk/2/hi/science/nature/7124156.stm

Chimps Short Term Memory Better than Humans http://uk.youtube.com/watch?v=khe9bXT-OHE&NR=1

My previous posts about chimps and monkeys:

Chimps share the human trait of altruism

Monkeys can estimate numbers as well as Duke students

U.S. labs import thousands of wild-caught primates

Chimps and gibbons have human elements to their speech

Research shows older females preferred as mates

Top 6 ways to protect wildlife from commercial trade

Wildlife trade, forestry, and the value of activism

Monkeylala (by Ken Kneidel)

Key words: chimps, chimpanzees, intelligence, animal intelligence, counting, short-term memory, Kyoto University

Chimps and Gibbons Have Human Elements to their Language

Gibbon photo courtesy of www.uq.edu.au

Researchers studying a population of wild gibbons in Thailand have found that these great apes recombine sounds to convey different meanings to one another, exhibiting a form of simple syntax.

The researchers, psychologists Esther Clarke and Klaus Zuberbuhler of the University of St. Andrews, claim that the ability to recombine sounds for varied meanings has not previously been demonstrated in apes. Their report was published in December of 2006 in the online journal PLoS ONE.

Before this study, psychologists had held that syntax developed in pre-historic people in response to a growing vocabulary. But this is not the case with gibbons, whose vocal abilities are limited. So perhaps previous theories about the development of syntax in humans will need to be reexamined.

The field studies of gibbon vocalizations, conducted in 2004 and 2005 with 13 groups of white-handed gibbons in Khao Yai National Park, focused on gibbon vocalizations for finding long-term mates and on vocalizations in response to predators. The research team recorded the two different kinds of songs. The songs provoked by predators began with soft "hoo" notes and included another repeated extra note, lasting altogether about 30 seconds. The mating songs were similar to the predator songs but lacked the "hoo" notes and the other extra note, and lasted only about 10 seconds.

Researchers played the recordings to other gibbons.

Gibbons within earshot responded vocally to the recordings, but responded differently to the two types of vocalizations, clearly distinguishing between the predator song and the mating song. Females responded to any song, but waited a full 2 minutes to respond to the predator call. All gibbons within earshot responded to the predator song by loudly repeating it.

This study demonstrates that great apes share some of our own facility for vocal communication.




My Work with Chimps

Although this gibbon research has been heralded as a new discovery of the capacity in apes for complex communication, we have known for decades that apes are capable of complex communication. Their development of language is limited by less versatile anatomy for vocalization than we have. That is, their lips and tongues and soft palates, etc., are unable to produce as many different sounds as we can produce. But researchers, since the 1960s and 1970s, have been teaching American Sign Language to chimps and orangutans and gorillas. These apes can also communicate by way of computer keyboards. As can some parrots.

For 2 years during my graduate training, I worked with Dr. Roger Fouts at the University of Oklahoma in his pioneering work teaching American Sign Language (ASL) to chimps. I was just a graduate student basically working as a research assistant - I was an additional pair of hands to help carry out his research. The object of his research was to see how much American Sign Language chimps could learn, and to see whether they would use it spontaneously with humans and with each other or even teach it to each other.

The chimps I worked with were mostly Bruno and Booee, two youngsters who were about 4 years old. My job was to work with one of them at a time, to get the chimp to go through a binder we had of photos that had been cut out of magazines. Each page had a picture of some object, like food, a ball, water, a bird, a hug, etc. The chimp was supposed to do the hand sign for the object and if he did it correctly, he got a sip of Kool-Aid or some other little tasty treat. Maybe an M&M. Of course, the chimps did not much want to look at the binder of pictures. This act of looking a book did not resemble any normal behavior in their repertoire, and they did not particularly want my approval, so getting them to sit still with the binder was not easy. Imagine a young child with full blown ADD, but 10 times magnified.

In fact, unless the instructor such as myself was very stern with the chimp during the lesson, the language lesson often devolved into the chimp jumping up and running around. On a bad day, the chimp would sometimes run back and forth past me, "accidently" bumping into me as he passed me, to see what I would do. This was a standard sort of bluff that was really a challenge. The chimps did it to everyone on the premises, to test their boundaries. But I was afraid of the little guys, who were by no means full grown, but weren't all that little. More than one of the senior graduate students had missing finger tips from being bitten by chimps during lessons. The chimps had collars and a chain, and I was supposed to grab that and make the chimp sit down. But the collar was within range of their sharp teeth.

The chimps knew I was a wimp and so I seldom made much progress in the language lessons. After a year and a half of trying to work with the chimps, and then with the orangutans in the nearby Oklahoma City Zoo, I decided I wasn't that interested in the language abilities of captive apes. That is, I wasn't very interested in getting them to behave like humans. I was much more interested in the natural behaviors of wildlife. So I transferred to the University of North Carolina to study the field biology of woodland salamanders.

But at any rate, there was merit to Dr. Fouts' studies, and to the continuing studies of one of those senior graduate students, Dr. Sue Savage-Rumbaugh who went on to study chimps' acquisition of language for 23 years at Georgia State University. (She's now with the Great Ape Trust of Iowa.) Both Fouts and Savage-Rumbaugh, as well as many other researchers by now, have shown that many apes can learn more than 300 different signs. It may be up to 600 by now, I don't know. Not only that, but when I was in Oklahoma, the chimps that we were working with used the signs to communicate with us and with each other. They regularly asked us for food or drink or to play with the ball, or for a tickle. One of the mother chimps taught some of the signs to her youngster. And - here's the best part - one of the chimps we worked with combined words in a unique way to apply to new objects. It was a new word for "duck." Bruno and Booee and a few other chimps lived on a small island surrounded by a moat to keep them from escaping. There were ducks on the moat on occasion. The chimps did not have a sign for duck, but one of them put together the sign for water and the sign for bird to make "water bird," for the ducks! That convinced me that chimps do have a profound capacity for understanding and using language - they just don't have the vocal apparatus. Gorillas too have been demonstrated to have extensive sign language capacity. Koko was the first gorilla to show this; her researcher was Dr. Francine (Penny) Patterson, who has written at least a couple of great children's books about Koko.

I have to say that I don't particularly approve of coercing chimps or any primates to participate in behavioral studies. And I vehemently object to taking any primates at all for any reason out of the wild. But chimps born in captivity probably have few good options. Learning sign language is preferrable to being subjected to medical research. But far better than either would be a reintroduction program to return them to the wild, or life in a primate sanctuary where they would be protected and have all of their physical, social and mental needs met, and be free to exercise their normal behaviors 24 hours a day.

Chimps are smart. They are much smarter than we think they are, and the language programs have gone a long way to show that. For that reason, the language research has been valuable. But it's only valuable if we pay attention to it. We should protect chimps and all other primates from the wildlife trade, from poaching, and from all other human activities that threaten their safety and their future existence. Their survival hangs in the balance as we continue to destroy their remaining habitat and remove animals from nature. I hope we can stop before we've eliminated our only close relatives on this planet.

KEYWORDS:: CHIMP CHIMPS APES GIBBONS GIBBON PRIMATES PRIMATE RESEARCH AMERICAN SIGN LANGUAGE VOCALIZATIONS SYNTAX PREDATOR SONG MATING SONG WILDLIFE TRADE POACHING HABITAT PRIMATE SANCTUARY