In 2007, Dr. Jill Pruetz reported an extraordinary discovery: chimpanzees in southeastern Senegal were using spears to hunt their food. And slightly stranger still, it seemed like the females were doing a lot of the spearing.

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Seven years later, the Iowa State scientist has returned from Senegal with seven years of data, including 308 successful recorded chimpanzee spear-hunts. And true to her early observations, it’s the female chimpanzees (by a ratio of about 3:2 over the males) that have embraced the way of the spear.

(Dr. Pruetz and her co-authors were thoughtful enough to publish all of this in an open access journal, so you’re free to read about this in their own words, for free!)

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Female chimpanzees are at a physical disadvantage to their male counterparts, largely because female chimpanzees are usually weighed down by helpless, nursing infants. (The males could probably assist with the “helpless” part, but they’re rubbish at “nursing”.) That extra baby-weight puts chimpanzee females at a speed disadvantage, which means the males usually hunt, and the females are left to gather.

But the Senegalese group lives in an area without much meat, and the males can’t hunt enough by themselves. The spears (a long stick chewed to a point, then cleaned off between hunts) give females enough of an advantage to overcome the literal burden of raising children, allowing the females to contribute around a third of the meat hunted by their group.

(The females also earned a number of “assists”, using their spears to wound and/or flush out prey that opportunistic males then grabbed. This opportunism may partially explain why male chimpanzees haven’t adopted spear use nearly as much as would be expected.)

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Because chimpanzee hunter-gatherer society shares some parallels with human hunter-gatherers (and probably also because Dr. Pruetz is an anthropologist), Dr. Pruetz has hypothesized that perhaps early hominin females paved the way for hominin tool use in hunting, just as chimpanzee females appear to be pioneering the technology in their social group. A simple wooden spear may have been enough for hominin females to shrink the gap between the “hunters” and the “gatherers”, ultimately reducing both sexes’ dependence on physical strength to survive.

(Since I’m far from the first to this party, you can read more about Dr. Pruetz’ findings and hypotheses at, just as three examples, the NY Times, phys.org, or New Scientist.)