See this stone? I’m going to make a really loud noise with it MPI-EVA PanAf/Chimbo Foundation

All hail the sacred tree. I’ve often wondered aloud in the newsroom about the possibility of finding evidence of a chimp shrine, the discovery of a place where chimps pray to their deity.

This week, my half-whimsical dream almost came true. Biologists working in the Republic of Guinea found evidence for what seemed to be a “sacred tree” used by chimps, perhaps for some sort of ritual.

Laura Kehoe of the Humboldt University of Berlin, Germany, set up camera traps by trees marked with unusual scratches. What she found gave her goosebumps: chimps were placing stones in the hollow of trees, and bashing trees with rocks.


Sign or symbol

The behaviour could be a means of communication, since rocks make a loud bang when they hit hollow trees. Or it could be more symbolic.

“Maybe we found the first evidence of chimpanzees creating a kind of shrine that could indicate sacred trees,” Kehoe wrote on her blog.

Of course it’s not proof that chimps believe in any kind of god, as the Daily Mail would have it, but it is the latest evidence of their extraordinarily rich behaviour.

In recent years we’ve seen chimps using spears to hunt bushbabies, going to war, and seemingly using doll-shaped sticks as toys.

I especially liked this last study, which found that juvenile wild chimps – more commonly females – played with sticks as children play with dolls, cradling them and even making nests for them to sleep in.

Here are a few stones we prepared earlier MPI-EVA PanAf/Chimbo Foundation

Rain dance

But most pertinent to the discovery of the “shrine trees”, we’ve seen evidence of chimps displaying strange ritual-like behaviour in the last few years. First, a “ritual” dance performed during rainfall. Then a peculiar slow-motion display in the face of a bush fire in Senegal.

Jill Pruetz of Iowa State University, who observed the “fire dance” in 2006, said that the behaviour seems to suggest that chimps have a conceptual understanding of fire. Perhaps they are paying respect to it, in some way. I’ve also heard stories of chimps performing dances in front of waterfalls.

Maybe chimps have some understanding of impressive natural phenomena such as rain storms, wild fires and waterfalls and are paying “respect” to them. So I always hoped that we’d find evidence of a “temple” in the forest.

Pruetz, who is involved in the new study, thinks the chimps bang stones to communicate. Many males drum on root buttresses as the noise carries further than the standard chimp cry, the pant-hoot, she says. But often there aren’t any trees with buttress roots, so perhaps they bang stones instead.

Bang if you can hear me

What about chimps storing stones in hollow trees, though?

“It does seem to be a tradition found in some groups,” she says. “If that fits the definition of proto-ritualistic, I have no problem with it.”

“It’s such a cool observation,” says primate cognitive psychologist Laurie Santos of Yale University. “But I worry that we don’t yet know how to interpret it.”

“In my monkey behaviour experience, low noises often serve a communicative function – males trying to act dominant, etc. – so my instinct is that this behaviour might work a lot like that,” she says.

Naturally, it’s way too soon to conclude that this is proto-religious behaviour. For one thing, even pigeons have been described as showing “superstitious” behaviour. “We’d need more observation – and perhaps actual experiments – to know if chimpanzees are using the behaviour as anything like a ritual,” Santos says.

Incidentally, I used to think of stories like these as chipping away at the various claims to uniqueness that we erected to separate us from other animals. For example the creation of musical instruments by wild apes, evidence that chimps show empathy, and intimations of mortality in a range of animals.

I don’t see it quite like that anymore. It’s hard to argue that we’re not unique when asked if chimps could build their own LHC, as one primatologist once asked me.

But I do see these stories as vital for the way they spectacularly illuminate our own roots. The evolutionary origin of religion is profoundly important to understanding human culture, for example. So it’s essential to examine any possible roots of this in other animals. And for their own sake, with all the conservation pressures chimps face, a deeper understanding of our closest relatives can only be a good thing.

Journal reference: Scientific Reports, DOI: 10.1038/srep22219

Read more: Rite reasons: Why your brain loves pointless rituals; Puzzles of evolution: Why aren’t we more like chimps?