Chimps and Lies

Not long ago, in my world-famous Audio Post (link), I mentioned that humans often point to things we do that other animals don’t do. We’re special because of X.

The Washington Post reports another chink in the “we’re special” argument (Link). Chimps are fashioning spears, then hunting and killing other animals with them.

This goes beyond sticking a branch into a termite mound to get some ants. This is more obviously a precursor to stone axes, or woven baskets.

I wonder how long this group of chimps has been doing it. And I wonder whether they learned it from other chimps. Have other chimps learned it from them? Do they use the spears on other chimps as well as on prey? And if not, how long before they will?

This is learned behavior and part of the group’s culture. Just as writing, or agriculture, spread across groups of humans, I expect that hunting with spears would spread among chimps. Or at least among those chimps living in an area where this kind of innovation would be helpful.


[Read a sort of literary spoof of this story on Language Log (Link).

The Lies (by humans)

The article says:

“The landmark observation also supports the long-debated proposition that females — the main makers and users of spears among the Senegalese chimps — tend to be the innovators and creative problem solvers in primate culture.”

It also says:

“…researchers documented 22 instances of spearmaking and use, two-thirds of them involving females.”

Now, I started wondering just exactly what that meant. For example, how many of the group’s 35 members were actually making spears? Let’s say there were only three chimps making spears, and 2 were female. Does that support the theory that the females are the innovators, or that they were the “main makers” of spears?

What if there are 2 males and one female using spears, but the female used them more often? Does that support the theory that females are the innovators?

So I looked up the actual report, in Current Biology (Link).

Guess what?

“Individuals observed fashioning or using hunting tools included one adult female, one adult male, three adolescent females, two adolescent males, one juvenile female, one juvenile male, and one infant male.”

In other words, when you look at how many individuals of each sex made spears, the score was:

Females: 5

Males: 5

That paints a slightly different picture, doesn’t it? There are as many males as females making spears.

And by the way, there are only 11 males in the whole group, allowing for yet another way to look at it: Almost 50% of the males made spears, whereas only 20% of females did.

The researchers did suggest a reason that female chimps might use spears more.

They say that maybe young and female chimps lack the social or physical means to get meat through traditional ways, so they find alternatives. So if you’re going to say that this study shows that females are the innovators, then you should also say that immature chimps of both sexes are innovators.

Which may be true! But that’s not really what the Post article said. For one thing, using spears may seem really exciting to us, but it’s actually solving a problem that the adult males don’t have!

The adult males don’t need new ways to get meat, because their old ways are working just fine (as good or better than using the spear, according to this same study). I think it would be reasonable to assume that they do solve problems that they actually face. It doesn’t seem quite right to say that females are the problem solvers just because we happen to watch while they (and the kids) solve a problem that the adult males don’t face.

And then, I’m not sure what to make of the partial quote in the Post, from one anthropologist, saying:

“females ‘are efficient and innovative, they are problem solvers, they are curious.’”

Does that mean that the males aren’t all those things? Or that they’re less so? Or does it have nothing at all to do with the males? My mistrust of reporters is great enough that I don’t feel comfortable inferring anything beyond possibilities of meaning.

And as far as the study in question, the quote wouldn’t seem to be accurate if applied to one sex over the other.

Anyway, some chimps use spears, which is pretty cool.

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