From opposable thumbs to the curse of ticklishness, humans and chimpanzees have a lot in common. So perhaps it’s no surprise that both species cultivate unique behaviors and intricate traditions that vary between communities are passed down through the generations.
In other words, we both have culture. But that might not be the case for much longer. According to a study published today in the journal Science, the culture of chimpanzees is vanishing alongside their habitats—and we’re to blame.
“It’s amazing to think that just 60 years ago, we knew next to nothing of the behavior of our sister species in the wild,” Andrew Whiten, a zoologist at the University of St. Andrews in the UK who was not involved in the study, told Ed Yong at The Atlantic. “But now, just as we are truly getting to know our primate cousins, the actions of humans are closing the window on all we have discovered.”
Thanks to decades of habitat destruction, poaching, and the spread of disease—all at the hands of humans—chimpanzees haven’t budged from their spot on the endangered species list since they joined it in 1990. But even when acreage itself isn’t at stake, human interference can take its toll on the wellbeing of these great apes, the study shows.
By cataloguing the activities of 144 chimpanzee communities in Africa, a team of researchers led by Hjalmar Kühl and Ammie Kalan, primatologists at the Max Planck Institute, found that 31 culturally ingrained behaviors, including nut cracking, termite collection, and bathing, tended to be stifled in the vicinity of human establishments. Across populations, the chimpanzees influenced most by humans had an 88 percent lower probability of displaying these distinctive behaviors.
As is the case with humans, culture for chimpanzees is more than a set of whimsical quirks. Some traditions have evolved within regional communities, outside of which they might not exist, reports Sarah Wells at Gizmodo. And many form the basis of key adaptations that, in several environments, could have a huge impact on survival.
How exactly humans are censoring chimpanzee culture is still being investigated, but the researchers already have some ideas. For instance, culling chimpanzee numbers could limit the opportunities individuals have to pass skills on to others. Alternatively, chimps might be hesitant to perform conspicuously noisy behaviors in an effort to avoid attracting human attention. Humans might even be sapping chimpanzee traditions indirectly by depleting key resources, like the tree nuts frequently cracked in certain communities.
All this goes to say that, when it comes to the urgency of conservation, more is at stake than once thought. “We need to pay attention to the social and cultural knowledge that these species use to survive” when trying to protect them, Kalan told Gretchen Vogel at Science.
And culture, once curbed, might be a difficult thing to reinstate. “An event might only have a small impact on the total population of chimpanzees, but it may wipe out an entire community—an entire culture,” Cat Hobaiter, a primatologist at the University of St. Andrews who was not involved in the study, told Yong at The Atlantic. “No matter what we do to restore habitat or support population growth, we may never be able to restore that culture.”