Central chimpanzee (Pan troglodytes troglodytes) termite fishing

Innovation. In a broad sense, it’s the social spread of a new idea or thing (as opposed to invention, which is the first creation of a new thing). Over the past few decades, however, this word has been hijacked by a small group of people based in the US, specifically around San Francisco. This Silicon Valley version defines innovation not as new things being created and spread, but as essentially any change that brings problems for your predecessors and money for you—oh, and it should definitely make the world a better place.

Everything that helps define a human culture, from clothes to language to cuisine to rituals to tools, is by definition an innovation. This pervasiveness—whether or not it’s tied to the messiah complex and disruption of Silicon Valley—can even lead to a belief that this is a peculiarly human trait. To be clear, it’s not. Behavioural flexibility is an option for all species over evolutionary time. The problem is one that we will stumble on repeatedly in this blog: human observation. We are rarely close enough for long enough to an animal’s natural behaviour to identify innovations as they occur, which means that we always underestimate their rarity. Just because I may be more attuned to a new iPhone’s colour than I am to how a bird builds its nest doesn’t make the latter any less innovative.

Fortunately, we also have dedicated field researchers like Crickette Sanz, David Morgan, and their colleagues and students. Thanks to them, in this post we can cover one clear example of non-human innovation: the insect gathering tool kits of chimpanzees in the Goualougo Triangle, Republic of Congo. If you want to make the world a better place, sometimes the best thing to disrupt is a termite nest.

Tapping, trapping & tasting termites

Some chimpanzee group use tools to eat termites. Others don’t. The behaviour is widespread enough, though, and involves sufficient animals of different subspecies living far apart across Africa, to say that this is a common innovation. It was, for example, among the suite of tool-use activities noted by Jane Goodall in her initial 1964 report on the Gombe chimpanzees in East Africa (along with using leaves as a sponge, using sticks to catch ants, and more).

Here’s a video from Sanz and Morgan’s Goualougo Triangle Ape Project, to give you a better idea of what we’re talking about:

All three chimpanzees in the video are harvesting Macrotermes muelleri termites from this large epigeal—Greek for ‘above-ground’—nest. The adult female in the bottom left of frame is more proficient than her kids, as shown in her almost nonchalant, repetitive insertion, consumption and re-insertion pattern.

Chimpanzee groups in the same Goualougo area also fish for termites that make their nests underground. Those nests, for example of the termite species Macrotermes lilljeborgi, require some extra effort to reach, since the flexible probe used to extract the termites isn’t tough enough on its own to drill down to the nest.

The solution is to add another tool to the kit. What Sanz and Morgan call a puncturing tool needs a very specific kind of material, one that is

very straight and rigid with a uniform diameter, smooth stalk surface, and few side branches.

As a result, 98% of the puncturing tools are chosen from one small tree that fits the bill, Thomandersia hensii. When this species isn’t found near the termite site, the animals will travel significant distances to find, detach, trim, strip and sharpen a solid section that is uniformly around 1cm thick.

And then they puncture the earth. The strength of the tool is matched by the strength of the user, with the animal’s whole body weight brought to bear on driving the stick down into the subterranean nest. Again, it’s best to see it for yourself:

Here, the male chimpanzee on the right is puncturing the nest below, while his mother and younger sibling are fishing from already open holes. As the puncture nears completion, the male first tries to take his sibling’s fishing probe—who rejects that idea—and then borrows his mother’s. When she wants it back, he again snatches the youngster’s tool away.

There is an equivalent tool for opening new holes in an epigeal nest, labelled a ‘perforator’ by the Goualougo team. It’s also tougher than the fine probe, but it doesn’t need to be as strong as the puncturing tool, as it just needs to break through a few centimetres of outer nest crust. What both nest types have in common, though, is the final tool in the process, that long thin probe that the chimpanzees repeatedly insert and withdraw. And at the end of that probe is the innovation we’re looking for.

Brushing up on your technique

On first thought, it’s easy to imagine that termites get kind of squished onto the end of the fishing tool as it’s inserted into their tunnels. That’s what I believed when I was a kid. Or maybe you could picture the end of the tool being sticky from chimpanzee saliva, so the termites get kind of glued on. But the reality is much more exploitative.

Termite nests are guarded by soldiers, who protect the workers, who in turn perform maintenance as well as feeding and caring for the children of the termite royalty. This arrangement is all part of the unwritten contract that governs eusocial animals, just as we saw for snapping shrimp and their cavitating claw. The main weapon of the termite soldier is its jaw, which is extremely large relative to both its own body, and to the heads of the workers it surveys.

You can easily spot the warrior class in this short video of Macrotermes muelleri busy at work, taken by the Goualougo team:

If they detect a foreign intruder, including a wandering chimpanzee probe, the soldier instinct is to clamp down on it, hard. In this way termite fishing really is similar to human line fishing, capturing animals that have been tricked into biting on something they shouldn’t. The soldier reaction happens so quickly that the probe can be sent into the nest over and over again without much of a pause, returning each time with a captive meal.

In East and West Africa, chimpanzees use a range of plant materials for termite fishing, including bark, twigs, vines and grass. The ends of those tools can get incidentally damaged or frayed with use, but in Goualougo the loose fibres at the business end of the tool are a defining characteristic. Have a look again at the videos, and at the tool held in the chimpanzee’s mouth in the image below. Notice that not only is there a lighter-coloured section of drooping material at one end of the probe, but that it’s straightened by the tool-user every time before insertion:

That brush tip is not accidental damage. It’s deliberately formed by each tool-maker, usually even before they get to a nest, most often by pulling the tip through the teeth. The brush makes inserting the tool more difficult, but in return the greater surface area captures more termites each time—a fact proved by experiments done by the Goualougo scientists. With a brush tip, the research team managed to extract termites 72% of the time, versus only 18% of the time with an unmodified tip (remember, that’s the kind used by most other chimpanzee groups, who seem to be missing a trick).

Stephanie Musgrave and the Goualougo team found that there is a sequence to how the chimpanzees learn the multiple parts of their termite extraction industry. At about 1 year of age, they start to identify the importance of holes in termite nests, and they play with abandoned tools. Two year olds can insert found probes into the nest, although it takes a little longer to learn to straighten those brush fibres before doing so. It’s not until they’re closer to 4 years old, though, that they can handle the whole sequence of making and successfully using their own brush probes. And it’s another few years before they get the hang of perforating and puncturing.

This learning curve is actually reasonably quick. Compared to the Gombe chimpanzees over in the east, the Goualougo youngsters learned how to extract termites at a younger age. Some Gombe individuals were over 5 years of age before they successfully fished for themselves, while every 3 year old Goualougo chimpanzee could do so (in both cases without adding brush tips). There are a range of social and environmental reasons that can help explain this precociousness at the Congo site—more sharing of tools, more termites available year-round—but at this point the mechanisms are still unresolved.

Insert innovation here

So, some wild chimpanzees in the Congo started with a stick, and made a better version of a stick. Isn’t this all a bit…underwhelming?

No. Definitely not. How could you say that? Here’s two of many reasons why not: (1) we’ve only been closely studying wild chimpanzees for a few decades, and we should not assume that they are currently at their creative peak; and (2) most humans couldn’t innovate a brush-tipped termite tool if their lunch depended on it.

These are basically the same argument, from different perspectives. The first emphasises that point from earlier about limited human observation. Innovations arise and spread, but their time-linked nature means that they also can disappear or be superseded (whether or not the innovating group lives on). What are the odds that we’ve started paying close scientific attention to chimpanzee behaviour just as members of this species hit their most complex innovation point? I’m not suggesting that past chimpanzees flew aeroplanes, but there are many species currently at a low point in their innovation abilities (hello again, non-avian dinosaurs), and a fair bit of earth’s evolutionary history passed by before binoculars or cameras were invented. In fact, today’s rapidly-endangered chimpanzee populations likely retain only a tiny sliver of the total behavioural diversity that has waxed and waned over time, in part precisely because of the havoc we’ve wreaked on them.

The second reason, that humans may not be as innovative as we imagine, is about overestimation. Recall that innovation is a successfully spread idea, not just you doing something new on your own. With that in mind, while we all may have some potential to innovate, the fact is that mostly we follow the crowd, taking part in other people’s innovations. We’re fortunate that, with over 7 billion of us at this point, mostly connected to each other and often freed from the need to collect our own food every day, there is simply more opportunity these days for innovations to be generated and spread. This point—about populations and innovations—is an important one that we’ll return to another time.

For now, just keep in mind that every invention builds on what came before, and most seem very obvious only after the fact. There are also innumerable constraints on what’s possible, ranging from how your body is put together, to what materials your local environment gives you to work with, to how often you get eaten if you try something new. Note that I’m also specifically not tying the Goualougo chimpanzees to some form of human-evolution-progress argument: they’re not our ancestors, just as we’re not their’s. As a separate data point in the comparative landscape of animal innovation, though, there’s a lot still to learn from chimpanzees.

Further viewing: here’s a final short video of a young female Goualougo chimpanzee and her mother, contently fishing away at a subterranean nest:

Sources: Reader, S. et al. (2016) Animal and human innovation: novel problems and novel solutions. Philosophical Transactions of the Royal Society B 371: 20150182. || Goodall, J. (1964) Tool-Using and Aimed Throwing in a Community of Free-Living Chimpanzees. Nature 201: 1264–1266. || Sanz, C. & D. Morgan (2007) Chimpanzee tool technology in the Goualougo Triangle, Republic of Congo. Journal of Human Evolution 52: 420-433. || Sanz, C. et al. (2014) Insect prey characteristics affecting regional variation in chimpanzee tool use. Journal of Human Evolution 71: 28-37. || Pascual-Garrido, A. (2019) Cultural variation between neighbouring communities of chimpanzees at Gombe, Tanzania. Scientific Reports 9, 8260. || Sanz, C. et al. (2009) Design complexity in termite-fishing tools of chimpanzees (Pan troglodytes). Biology Letters 5: 293-296. || Musgrave, S. et al. (2020) The ontogeny of termite gathering among chimpanzees in the Goualougo Triangle, Republic of Congo. American Journal of Physical Anthropology 2020: e24125 ||

Main image credit: Stephanie Musgrave, https://leakeyfoundation.org/from-the-field-stephanie-musgrave || Second image credit: Ian Nichols, National Geographic, https://www.nationalgeographic.com/magazine/2010/02/congo-goualougo-triangle-chimpanzees || Video credits: Goualougo Triangle Ape Project, https://www.youtube.com/user/Goualougo/videos