"Carriers regularly take sticks into the nests they rest in during the day, something that isn't done with other objects. "The stick serves no immediate function, they just carry it-sometimes for a few minutes, other times for hours," study leader Richard Wrangham, a biological anthropologist at Harvard University, said via email. (See "Orangutans 'Play Charades' to Communicate With People.") The behavior, which was very rarely observed in males, has been witnessed more than a hundred times over 14 years of study. Young females of the Kanyawara chimpanzee community in Kibale National Park, Uganda, use sticks as rudimentary dolls and care for them like the group's mother chimps tend to their real offspring. Now new research suggests that such gender-driven desires are also seen in young female chimpanzees in the wild-a behavior that possibly evolved to make the animals better mothers, experts say. The team say the environmental pressures of living in the hot, dry Savannah and the incentive of keeping nutritious prey might have encouraged these chimps, who could be less able to run down prey or catch them with their bare hands, to learn to hunt with tools.It's almost Christmas, and, as the song goes, Barney and Ben hope for Hopalong boots and a pistol that shoots, while Janice and Jen would like dolls that will talk and go for a walk. In many locations a higher ranking chimp might steal captured prey from a female or low status male, in Fongoli theft of prey is rare. It could be that other chimps never learned the technique or that a particularly socially tolerant environment at Fongoli has led to female and lower-ranking chimps also learning to hunt. The team say it’s unclear why the Fongoli chimps use tools but other chimps don’t. One explanation for the difference in tool use between the sexes could be that male chimps tend to be more opportunistic in their hunting than females- sometimes grabbing fleeing bush babies who have managed to evade a female hunter. In other environments adult male chimpanzees are usually seen as the primary hunters so the proportion of female chimps using tools to hunt is an intriguing finding for researchers. Males led just 40% of the hunts even though on hunting days they made up 60% of the chimpanzee pack. Of the 308 hunts the researchers recorded, 175 were carried out by females and just 130 by males. Though overall males were the more successful hunters in the Fongoli area, when it came to tool use, females took the lead. The team studying the chimpanzee population found that most of the tool-assisted hunts recorded were carried out by female chimpanzees. The chimpanzees in the area have been seen snapping off pieces of branches and stripping them down to make spears which they stab into holes in trees where their bush baby prey could be hiding. Meat does not make up a large portion of a chimpanzee’s diet but they regularly hunt small vertebrates like bush babies for valued nutrients. Studying these tool-using primates could give an insight into the importance of hunting in human evolutionary history, filling in some of the gaps in our understanding of how and why our ancestors started using tools. This community is the only known non-human animal to regularly use tools to hunt chimps in other areas don’t seem to have picked up on the trick. The study presents results from Fongoli in Senegal where the chimpanzees hunt their prey with tools.
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