“Chimpanzee Fire”

I recently watched a BBC documentary about the Congo. It was part of a larger documentary series on Africa narrated by David Attenborough that I highly recommend. Whenever I watch BBC nature documentaries I feel like I learn something new each time. But while I was watching Congo, one scene in particular caught my attention. It was a scene on “chimpanzee fire.” Immediately my curiosity piqued. In the scene, a camera panned across a dark forest floor, and within moments it started coming to life with a green glow.

Was it chimpanzee fire? Unfortunately, it was not. It was bioluminescent fungi that the local Congolese call “chimpanzee fire.” Bioluminescence is the production and emission of light by a living organism. Several animal, plant, and fungi species have adapted the ability to produce their own light, and it serves many important functions. I actually had a chance to learn a lot about bioluminescence at an amazing exhibit at the American Museum of Natural History in New York over the winter break.

It is easy to see why the native Congolese would have started to call this bioluminescent fungi chimpanzee fire. Modern science has only started to understand how bioluminescence functions and evolves. And it is kind of counterintuitive to think of organisms that have the ability to produce their own light. In the early modern era or pre-modern era, I think I would have been far more convinced by the chimpanzee fire hypothesis.

But this little anecdote about chimpanzee fire from the Congo reminds us of something more interesting: people in many areas of sub-Saharan Africa likely realized chimpanzees were behaviourally similar to humans for tens of thousands of years. Positing that chimpanzees had the ability to ignite fire across the forest floor is laden with symbolic meaning about our connection with them. And it is not hard to see why they would have attributed the glow to chimpanzees. In fact the name chimpanzee is derived from Tshiluba (a Congoloese language), and translates roughly as ‘mockman.’ This further supports the idea that we didn’t necessarily need modern science to reason that chimpanzees were human-like. Just like the Ancient Greek philosophers didn’t need telescopes to reason that the stars could be just like our Sun, only further away.

But let’s turn our attention back to fire. Sure the bioluminescent fungi were not chimpanzee fire, but can any populations of chimpanzee control and use fire? After all, most behavioural differences between chimpanzees and humans are really best thought of as gradient differences. Do any chimpanzees gather around a little campfire for warmth? Or light a torch to get through the forest at night?

Recent research at Fongoli in Senegal has revealed some interesting findings. Populations of chimpanzees at Fongoli behave a lot differently than many other populations studied to date. They are the only non-human organisms on the planet known to hunt other animals with weapons. They also periodically live in caves and travel at night. And unlike most other chimpanzee populations, they seem to have developed a fondness for water. But do they use and control fire?

Primatologist Jill Pruetz claims that the Fongoli chimps are confronted with fire more than other chimpanzee populations. They live in a savanna-mosaic environment and as a result wild fires spread more frequently than in the habitats of other chimpanzee populations. When confronted with these fires they seem to be able to “predict the movement.” (Pruetz & LaDuke, 2009). Pruetz says that in such situations she chooses to follow the chimpanzees rather than find her own path out of the woodland.

Despite this, no Fongoli chimp, or any other chimp, has ever been observed to control and use fire. That appears to be an ability acquired after our split with chimpanzees and bonobos. However, this leads to an interesting question: when did we start using fire? And what benefits did using fire have?

The question is harder to answer that it seems. The beginnings of most distinctively human behaviours leave little-to-no trace in the archaeological record. When it comes to understanding the origin of things like language or tool construction, theory has less testable evidence than would be ideal. In the case of fire, traces of fire use are easily and quickly destroyed by wind and rain, so acquiring direct evidence of early campsites may be impossible. That being said, we have uncovered some answers regarding the origin of the control and use of fire. This evidence is indirect, but reliable.

Paleoanthropologists believe they have pushed the origin of fire control and use to approximately 1.7 million years ago. The evidence comes from Wonderwerk Cave in South Africa, where stratified deposits have produced burned cryptocrystalline stones, charred-calcined bones, and traces of ash, which indicate repeated burning events (Beaumont, 2011).

These deposits are associated with the remains of Homo ergaster, the African sister species to Homo erectus. Evolutionary anthropologists have known for a while that Homo erectus controlled and used fire, but the deposits at Wonderwerk push back its origin by hundreds of thousands of years.

Researchers have hypothesized that Homo ergaster regularly constructed campfires as they would have had considerable protection benefits on the southern savannas against a formidable array of carnivores. From my own research on chimpanzee nesting patterns, I believe that fire may have been a necessary behavioural adaptation to successfully migrate into a terrestrial niche. If my hypothesis is accurate, we should expect the origin of fire to be pushed back several millions of years. Alas, we don’t have evidence for that… yet.

Either way, fire may have provided our ancestors with an even greater benefit than protection from predators: cooking. Fire allowed our ancestors to prepare and cook meals (Wrangham, 2009). British primatologist Richard Wrangham recently wrote an entire book on the origin of fire and how it changed our species. He posits that cooking increased food efficiency, which enabled larger brain growth. His hypothesis is largely supported by current theory and evidence. It is also interesting to note that modern humans are highly evolved for eating cooked food, and if not prepared properly, raw food can be lethally poisonous to our digestive tract.

As human-like as chimpanzees can be, they do not control and use fire in the wild (even though they can be taught by humans). The original discovery that fire can be controlled and used for our benefit may have been the product of one ancient genius, or it may have been stumbled upon several hundreds of times. It seems that we will never have precise knowledge of how it exactly happened. However, we do have important knowledge of where it was made, when it was made, and what species discovered it. Future research should help us better understand how this happened, and consequently, it will help us reconstruct our current story of how we became human.  And you can help make future primatological discoveries possible by helping the Jane Goodall Institute of Canada continue field research throughout AfricaThe next big discovery is only one field season away.

References

Beaumont, P.B.  2011.  The Edge: More on Fire-Making by about 1.7 Million Years Ago at Wonderwerk Cave in South Africa.  Current Anthropology, 52: 585-595.    

Pruetz, J.D. & LaDuke, T.C.  2009.  Brief communication: Reaction to fire by savanna chimpanzees (Pan troglodytes verus) at Fongoli, Senegal: Conceptualization of “fire behavior” and the case for a chimpanzee model.  American Journal of Physical Anthropology, 141: 646-650.

Wrangham, R.  2009.  Catching Fire: How Cooking Made Us Human.  New York: Basic Books.

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