Chimpanzees at four different sites in Africa have been observed practising rituals which look eerily like the idol or God worship and shrine-building that humans have been doing for thousands of years. They were seen throwing stones at specific trees and building stone piles at their bases.
The international team of zoologists, animal psychologists and evolutionary anthropologists explained in the journal Scientific Reports that these ritualistic behaviours observed in chimpanzees were not at all linked to foraging (searching for food in the wild).
What these animals appear to be doing looks like a ritual, with the tree as the idol – an object of worship or reverence. If this is the case, Chimpanzees must be much higher up the evolutionary ladder than previously thought.
Chimpanzees were seen picking up large stones and hurling them at specific trees, which also had stone piles at their base. (Image: Max-Planck-Gesellschaft)
Some of our readers, after looking at the video and reading about the ritualistic behaviours, have suggested it might be a sport-related activity – the equivalent of target practice or shoot the hoops (practice basketball) in the world of chimpanzees.
Experts say chimpanzees are skilled users of tools, which they commonly use to get food. What type of tools they choose to utilize generally varies depending on the region where they live.
Scientists from the Max Planck Institute for Evolutionary Anthropology in Leipzig in Germany said it was during their activities within the Pan African Programme: The Cultured Chimpanzee (PanAf) that they witnessed these mysterious and fascinating behaviours.
The researchers say they cannot explain what the purpose of the stone hurling and making piles might be. They believe the behaviours probably have some cultural elements.
For the past sixty years, chimpanzees have been studied extensively at several long-term field sites, most of them in East and West Africa.
We have known for a long time that chimpanzees use tools for a variety of purposes. Studies have shown that they also design and make them. (Image: thecuriousape.com)
Chimpanzees are probably the most proficient tool users after humans. They use tools for getting at termites, fishing, scooping ants out of cracks and holes, and extracting honey. They have also been observed using wooden and stone hammers to crack open nuts.
They have also been seen using tools in non-foraging contexts. Males will sometimes throw branches and stones during displays, or leaf-clip as a way of communicating to females that they want sex. Nature photographers have had chimpanzees throw stones at them.
In order to better understand the evolutionary and ecological drivers of behavioral diversification in chimpanzees, the PanAf project was established by the Department of Primatology at the Max Planck Institute for Evolutionary Anthropology.
Hjalmar Kuehl, from the German Centre for Integrative Biodiversity Research and the Max Planck Institute for Evolutionary Anthropology, said regarding the PanAf project:
“The PanAf project represents a new approach to studying chimpanzees and will provide many interesting insights into chimpanzee demography and social structure, genetics, behavior and culture.”
“The Pan Af is only possible due to the numerous collaborations with chimpanzee researchers, field workers and national wildlife authorities in 14 countries across Africa.”
As the chimpanzees were not accustomed to humans, the researchers used several non-invasive sampling methods, including hidden camera traps.
This image was taken by a hidden camera at Boé, Guinea-Bissau, Africa. The ritual was accompanied by loud vocalizations. What drives them to do this? (Image: nature.com)
Stone piles revealed by cameras
Some cameras at the Chimbo Foundation in Guinea Bissau filmed footages that clearly showed what the scientists had suspected – the chimpanzees were regularly visiting the trees with piles of stones at their bases and throwing stones at them and adding to the piles, i.e. the chimps were the culprits.
Ammie Kalan, from the Max Planck Institute for Evolutionary Anthropology, said regarding what they saw on the video recordings:
“The PanAf cameras filmed individual chimpanzees picking up stones from beside, or inside trees, and then throwing them at these trees while emitting a long-distance pant hoot vocalization.”
They noticed that the males were the main throwers and hurlers of stones, although in some instances females and juveniles were also seen taking part.
Flow chart describing the behavioural elements observed in chimpanzee accumulative stone throwing. (Image: adapted from nature.com)
Stone hurling not foraging-related
No animal expert or local residents in West Africa had ever seen this type of behaviour before. It was clear that what they were doing had nothing to do with searching for food, the authors wrote.
Christophe Boesch, director of the Department of Primatology at the Max Planck Institute for Evolutionary Anthropology, said regarding our closest living relative:
“This study reports a new chimpanzee behavior not known previously and highlights the potential of the PanAf project to uncover unknown facets of the life of chimpanzees, our closest living relative.”
“As the stone accumulation behavior does not seem to be linked to either the abundance of stones or the availability of suitable trees in an area, it is likely that it has some cultural elements.”
Are chimps doing what we used to do?
Researchers frequently use chimpanzees as models of hominins. After finding these mysterious stone piles linked to their newly discovered behaviours, the authors wonder whether we might gain any insights into how stone accumulations in archaeological sites were made.
The authors believe that ritualistic behaviours of modern chimpanzees might shed some light on the origin of ritual sites in human evolution.
In an Abstract in the journal, the authors wrote:
“This represents the first record of repeated observations of individual chimpanzees exhibiting stone tool use for a purpose other than extractive foraging at what appear to be targeted trees.”
“The ritualized behavioural display and collection of artefacts at particular locations observed in chimpanzee accumulative stone throwing may have implications for the inferences that can be drawn from archaeological stone assemblages and the origins of ritual sites.”
Citation: Ammie K. Kalan, Hjalmar S. Kühl, Christophe Boesch et al. “Chimpanzee accumulative stone throwing.” Scientific Reports. 29th February, 2016. DOI: 10.1038/srep22219.
Video – Mysterious chimpanzee behaviour
Are the chimpanzees in this video performing ‘sacred’ rituals – building shrines like humans have done for thousands of years?