Chuck Bednar for redOrbit.com – @BednarChuck
Female chimpanzees create spears in order to stab their prey, suggesting that the ability to craft these kinds of weapons originated with early primates and that ancient humans may have hunted in a similar manner, according to a new Royal Society Open Science study.
The authors of that paper observed chimps living in Fongoli, Senegal as they took living tree branches, removed all of the leaves and side branches, then sharpened the edges of the tools with their teeth to create an effective weapon that was about 30 inches long.
Weapons made it possible for female chimps to hunt
Lead author Jill Pruetz, a professor in the Iowa State University Department of Anthropology, and her colleagues told Discovery News that they watched as one of the chimps would sneak up on a bushbaby, then stab it to death as the nocturnal creature slept in a nearby tree cavity.
They also found that the female adult chimps were more likely to make and use spears than the adult male ones, with the latter relying more upon their size and strength to hunt. Since females often have infants riding on their backs or bellies, using a spear for hunting is an easier and more effective way for them to track down and deal with their prey.
The authors wrote that adult male chimps accounted for 70 percent of all prey captures, but that tool use made it possible for “individuals other than adult males to capture and retain control of prey,” and that similar hunting methods may also have been used by early hominins.
Pruetz went on to state that she believes that the world’s first spear was invented by a female primate, since in many species, they are “the innovators and more frequent tool users… I think it is possible that a female invented this technique,” she told Discovery News on Tuesday.
What tool use in chimps tells us about evolution
Chimps living in the Fongoli region are the only known non-human primates that use weapons to hunt large prey, she and her colleagues found, and adult males support the efforts of females and younger males by allowing them to keep their own kills: an unusual gesture, since in most chimp groups, the dominant males tent to steal prey from their subordinates.
“The explanation for the pattern of tool-assisted hunting at Fongoli,” the authors wrote, “is that such hunting enables individuals who would be less likely to chase down larger vertebrate prey access to an energetically and nutritionally valuable food resource in a patchy savannah environment,” adding that the discovery “supports the hypothesis that early hominins intensified their tool technology to overcome environmental pressures and that even the earliest hominins were probably sophisticated enough to fashion tools for hunting.”
“The behavior of these chimpanzees demonstrates that hunting is less adult male-biased among our closest living relatives than previously believed when tools are used, and emphasizes the need to take into account the range of behavioral variation within a species, specifically when findings are applied to attempts to understand evolutionary adaptations,” they added.
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