海角大神

Chimps and tools: The boys play, while the girls learn

Researchers find that chimpanzees and bonobos, humans' closest cousins, interact with objects in distinct ways depending on their gender.

When children play with toys, they learn useful skills for adulthood. Young chimpanzees are no different, say scientists.听

According to a paper published Wednesday in the journal聽PLOS ONE,聽immature chimpanzees interact with objects .听

The young males engaged in object manipulation more frequently, and they used objects for play more often than the females did. The females used objects to achieve goals, explore their surroundings, or for other useful tasks, the researchers reported.听

A team of researchers led by University of Zurich anthropologist聽Kathelijne Koops, observed聽young wild chimpanzees in Uganda.听Initially they were perplexed by what they saw.听

Adult female chimpanzees have been observed using tools more frequently than males, which led researchers to suppose that young female chimps would manipulate objects more too. But that was not the case.听

鈥淚t became clear that in the male chimpanzees鈥� object manipulation was mainly play. A lot of it was running around with a twig or chasing each other with a branch, with leaves or something like that,鈥� Dr. Koops says in an interview with 海角大神. 鈥淚n the females it was much less play dominated and more goal directed, more diverse.鈥�

鈥淭hat does suggest that they are in a sense practicing or 鈥榩reparing鈥� for tool use in adulthood,鈥� she says. 鈥淲hereas in the males it looks like this object manipulation in play might be more linked to practicing motor skills and potentially male-specific behavior such as dominance displays.鈥�

Humans, it turns out, aren't much different.

鈥淲hen I started digging into the human literature, I found that often they actually report a male bias in object manipulation as well,鈥� says Dr. Koops. But that behavior, too, was more about play than tool development. 鈥淲e do see a similar pattern in humans and chimpanzees which might suggest that our common ancestor had a similar behavior.鈥�

Scientists long held that what sets聽humans set apart from other animals is our use of tools. But humans鈥� hairy cousins have been spotted using tools for foraging, cracking open nuts, and other uses.听

Jane Goodall was the first to spot a chimpanzee using tools, when in 1960聽she spotted a male using a piece of grass to pull termites out of their mound.听

When a chimp "fishes" for termites, as it's called, he or she pushes a stick or piece of grass into the termite mound. The termites latch onto the object, and the chimpanzee pulls the stick back out and swipes the crunchy meal off the tool and into his or her mouth. This method has also been observed with ants and other bugs.听

Improved tool use

The chimpanzees also chose different tools as they matured.听

鈥淭he youngsters below three years old manipulated much more leaves. As they got older, they started focusing more on sticks, which is the tool type that they use in this community,鈥� says Koops.听

鈥淚t looks like as they get older, the chimps are starting to focus more on what is actually a relevant tool material.鈥�

Bonobos

Chimps are not the only close human cousin that researchers observed.听In the Democratic Republic of Congo,聽they also watched the chimpanzees closest relative, the bonobo.

鈥淭he bonobos鈥攖hey鈥檙e as closely related to us as chimpanzees鈥攗se very few tools and no tools in foraging,鈥� says Koops.听

So the researchers weren鈥檛 surprised to see the young bonobos play with objects socially, which 鈥渇its their character as the playful apes,鈥� Koops says.听

There was no sex difference among young bonobos, they all ran around playing with each other.

鈥淲e knew that chimpanzees use more tools than bonobos, but we didn鈥檛 know so much as where this difference comes from,鈥� says Koops. 鈥淚t seems to be something that鈥檚 intrinsic.鈥� Chimpanzees intrinsically seem to be more object-oriented than bonobos, she says.听

The researchers become the tools

鈥淓ven after studying chimpanzees for 12 or 13 years, they still surprise you very often,鈥� says Koops.听

While Koops was observing the chimpanzees one day, she witnessed a special case of social tool use.

鈥淲e had one adult male who was fighting for the top rank in his group. He was very comfortable with people,鈥� having grown up with researchers around, she says. 鈥淗e wasn鈥檛 afraid of us.鈥�

鈥淭he two other males were much less comfortable with us because they were older, so they weren鈥檛 as used to us,鈥� she explains.

鈥淥ne day when the other two males were forming a coalition against him, he just came to sit behind us, basically using us as a tool against the males,鈥� Koops says.听

Despite being covered in hair, chimpanzees and bonobos are remarkably close relatives to humans. We share about with these apes.听

Being such close cousins, we could learn a lot about ourselves through studying these primates.

鈥淲e can learn so much about how we became the way we are and how we evolved to be who we are today from our closest living relatives, the chimpanzees and bonobos,鈥� Koops says.听