Primatology.net

Even though I’ve been posting a lot on tool use lately, I’m sure you will appreciate this new study. The new study, “Invention and modification of a new tool use behavior: ant-fishing in trees by a wild chimpanzee (Pan troglodytes verus) at Bossou, Guinea,” has been published in the most recent issue of the American Journal of Primatology. The writeup is very simple and informative, which is great because I consider this a very important paper in figuring out the origins of tool use and the intricacies of primate behavior.

The scope of this paper is a report on tool use seen in a male chimpanzee from Guinea. Tool use has been documented in several other wild chimpanzee societies, most notably was Goodall’s observations of Gombe chimps using tools. Since then other researchers have seen other wild chimps use tools, particularly using rocks to crack nuts open, and using twigs and sticks to fish or dip for ants. Ever so recently, we read and saw a Fongoli chimp hunt with a makeshift spear.

The clincher behind chimpanzee tool use in the wild use has been that it seems to be localized within the group that the behavior is observed in. This has gotten many researchers to hypothesize that this is some group specific behavior, a cultural trait per say. Researchers had no idea how tool use behaviors emerged in these respective groups, nor how long they have been practicing tool use.

In this new study, JJ, the male chimpanzee was the only chimpanzee in his group seen selecting for sticks used to fish for ants in a two year time period. This group of chimpanzees from Bossou has been studying for 27 years and this behavior has never been observed before. So his tool use tendencies seem to be novel amongst this group. Throughout the two years of observation, JJ progressively modified the optimal fishing stick, selecting for shorter and shorter ones. This indicates that JJ learned the characteristics of the best tool, one that would yield more ants.

Unfortunately, no observation has been made of JJ transmitting this behavior to other Bossou chimps. But it does indicate several thing… tool use can independently arise in chimpanzees, regardless of the fact that the group as a whole practices tool use or not. Also, it provides an insights into the cognitive capacity of wild chimps, like JJ, to problem solve and modify their behavior.

Yamamoto, S., Yamakoshi, G., Humle, T., Matsuzawa, T. (2008). Invention and modification of a new tool use behavior: ant-fishing in trees by a wild chimpanzee (Pan troglodytes verus) at Bossou, Guinea. American Journal of Primatology DOI: 10.1002/ajp.20544

Last month Ayumu and five other chimpanzees made the news because of their outstanding cognitive performance. They even beat out college students in their tests. The results of the study was reported in Current Biology, “Working memory of numerals in chimpanzees.”

If you don’t believe me check out the video of Ayumu rocking the test:

Very impressive performance. Luminosity Games has remade Ayumu’s game. If you wanna try to see if you’re any better than Ayumu, give it a shot here. I’m not very good at the game.

I’ve been unable to post on a lot of important primatology news as of late, I’ll try to catch up this weekend.

But I’m making time to quickly announce that Washoe has died. She was 42 years old and one of the first apes that was taught sign language, about 300 signs. She was known for her sweet, endearing soul. She even made signs for words she didn’t know.

Rest in peace, Washoe.

Boing Boing is on fire, first they post on Bill Bass and now they post on a new study from Smithsonian which reviews the,

“traits that [chimpanzees and humans] share, like altruism and vengeance, and those we don’t, like spite and most social learning skills, are shedding light on what it means to be human.”

So check out the article, “Animal Insight.” It is a pretty good review.

Michael Tomasello, one of the biggest and best primatologists out there, recently published a paper in Science on chimpanzee rationality. He and his colleagues setup a game where a human or chimpanzee receives something of value, and is able to share it with another.

He found some interesting results. Generally speaking, humans made offers close to 50 percent of the reward, but chimpanzees almost consistently made offers of substantially less than 50 percent, and accepted offers of any size, no matter how small. Tomasello and crew concluded that chimpanzees do not show a willingness to make fair offers and reject unfair ones. In this way, they protect their self interest and are unwilling to pay a cost to punish someone they perceive as unfair.

Here’s a link to the publication along with the abstract, “Chimpanzees Are Rational Maximizers in an Ultimatum Game,”

“Traditional models of economic decision-making assume that people are self-interested rational maximizers. Empirical research has demonstrated, however, that people will take into account the interests of others and are sensitive to norms of cooperation and fairness. In one of the most robust tests of this finding, the ultimatum game, individuals will reject a proposed division of a monetary windfall, at a cost to themselves, if they perceive it as unfair. Here we show that in an ultimatum game, humans’ closest living relatives, chimpanzees (Pan troglodytes), are rational maximizers and are not sensitive to fairness. These results support the hypothesis that other-regarding preferences and aversion to inequitable outcomes, which play key roles in human social organization, distinguish us from our closest living relatives.”