{"id":1086584,"date":"2026-07-13T13:09:20","date_gmt":"2026-07-13T13:09:20","guid":{"rendered":"https:\/\/www.europesays.com\/uk\/1086584\/"},"modified":"2026-07-13T13:09:20","modified_gmt":"2026-07-13T13:09:20","slug":"chimpanzees-have-been-throwing-stones-at-the-same-trees-for-years-and-scientists-still-dont-know-why","status":"publish","type":"post","link":"https:\/\/www.europesays.com\/uk\/1086584\/","title":{"rendered":"Chimpanzees have been throwing stones at the same trees for years, and scientists still don’t know why |"},"content":{"rendered":"

\"Chimpanzees In a stretch of savanna woodland inside Bo\u00e9 National Park in Guinea-Bissau, certain trees look strangely different from the rest. Small piles of rocks sit scattered around their base, and their bark carries the marks of repeated impact, evidence of a behaviour that has puzzled primatologists for years. Wild western chimpanzees, mostly adult males, return to these same trees again and again to hurl stones at them, a ritual known as accumulative stone throwing. Researchers recently spent time at one such field site trying to understand what this strange, noisy display actually means, and whether it could reveal something deeper about how communication and tool use evolved in our closest living relatives.<\/p>\n

The unusual stone throwing ritual of wild chimpanzees <\/p>\n

Accumulative stone throwing is exactly what it sounds like, chimpanzees repeatedly throwing rocks at specific trees over long stretches of time, sometimes for more than a decade. Video footage has captured chimpanzees hurling stones at particular trees and returning to the same spot to do it again, a behaviour first documented in a 2016 study<\/a> that helped bring wider attention to this unusual ritual. The displays are anything but subtle, chimpanzees often pant-hoot loudly while throwing, a call known to carry over long distances<\/a> through the forest, and some also slap and stomp on the tree trunk in a behaviour called buttress drumming.<\/p>\n

Why scientists think this behaviour is cultural<\/p>\n

What makes this ritual so interesting to researchers is how limited it seems to be. The behaviour has only been recorded in four chimpanzee communities across West Africa, and simply having rocks and trees nearby does not guarantee a group will start this practice. Because it shows up in some populations and not others despite similar surroundings, researchers believe accumulative stone throwing is likely a learned, cultural behaviour rather than pure instinct. Earlier work has suggested the ritual may serve a communicative or even symbolic purpose, with these sites possibly marking meaningful spots within a chimpanzee group’s home range.<\/p>\n

Studying stone-throwing sites in Guinea-Bissau<\/p>\n

To dig deeper into this mystery, researchers travelled to the remote Bo\u00e9 chimpanzee territory in Guinea-Bissau, setting up base in a small village called B\u00e9li before hiking and cycling around 22 kilometres into the bush to establish a research camp. Since the chimpanzees at this site are unhabituated and simply run off at the sight of humans, the team could not observe them directly and instead relied on camera traps and audio recorders placed at known stone throwing sites. Each day involved visiting several of these sites to swap out memory cards and batteries, check equipment, and record measurements of the trees along with 3D scans of the stones piled beneath them.<\/p>\n

What the camera trap data could reveal<\/p>\n

The video and audio collected during this fieldwork will help researchers examine details like the age and sex of the chimpanzee doing the throwing, along with how other nearby chimpanzees react to it. This kind of detail matters because pant hooting and buttress drumming are already known parts of typical male chimpanzee displays, which raises the possibility that accumulative stone throwing might simply be an extension or modification of behaviour chimpanzees already use to communicate. Interestingly, the team also found that most of the sites first documented years earlier through the Pan African Programme<\/a> were still actively being used by chimpanzees during this latest visit, showing just how long-lived these traditions can be within a single group.<\/p>\n

Why chimpanzee culture matters for conservation<\/p>\n

\"WhyBeyond satisfying scientific curiosity, understanding rituals like this ties into a much bigger conversation around animal culture and conservation. Researchers argue that cultural behaviours can help primate populations adapt to environmental change<\/a> and can even strengthen the broader case for protecting their habitats<\/a>. Losing behaviours like accumulative stone throwing would not just mean losing an odd quirk of chimpanzee life, researchers describe it as the erasure of a genuine form of primate heritage, since these are physical, durable traces of chimpanzee tradition passed down over generations.<\/p>\n

The growing threat from bauxite mining<\/p>\n

Unfortunately, this same landscape faces a real and immediate threat. Chimpanzee habitat across Guinea-Bissau is increasingly at risk from industrial mining, particularly bauxite extraction, and researchers came across active mining exploration boreholes during their time in the field. While bauxite mining could bring genuine economic growth to the region, it also carries the risk of habitat destruction and pollution, effects already visible in neighbouring Guinea. Given the added complications of unstable governance in Guinea-Bissau, researchers are calling for stronger environmental oversight to protect both the chimpanzees and the wider ecosystem they depend on.<\/p>\n

A window into deep evolutionary history<\/p>\n

Since chimpanzees are among our closest living relatives, understanding why they choose specific trees, why stones pile up at these locations, and how the ritual fits into their social lives could offer real clues about the evolutionary roots of communication and tool use in general. By continuing to study and document behaviours like accumulative stone throwing, researchers hope to support chimpanzee conservation efforts while also preserving a rare piece of primate cultural history for future study, before mining, habitat loss or other pressures have the chance to erase it completely.<\/p>\n","protected":false},"excerpt":{"rendered":"In a stretch of savanna woodland inside Bo\u00e9 National Park in Guinea-Bissau, certain trees look strangely different from…\n","protected":false},"author":2,"featured_media":1086585,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":"","_share_on_mastodon":"0"},"categories":[3847],"tags":[297091,297093,297094,297098,297092,198444,297095,70,297097,16,15,297096,1717],"class_list":["post-1086584","post","type-post","status-publish","format-standard","has-post-thumbnail","category-wildlife","tag-accumulative-stone-throwing","tag-bauxite-mining","tag-chimpanzee-communication","tag-chimpanzee-conservation","tag-chimpanzee-culture","tag-guinea-bissau","tag-primate-heritage","tag-science","tag-tool-use-evolution","tag-uk","tag-united-kingdom","tag-wild-chimpanzees","tag-wildlife"],"share_on_mastodon":{"url":"https:\/\/pubeurope.com\/@uk\/116912835290365998","error":""},"_links":{"self":[{"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/posts\/1086584","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/comments?post=1086584"}],"version-history":[{"count":0,"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/posts\/1086584\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/media\/1086585"}],"wp:attachment":[{"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/media?parent=1086584"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/categories?post=1086584"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/tags?post=1086584"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}