If you think it’s been a hot summer in America, try living in southeast Senegal, especially in the dry savannah area of Fongoli where temperatures rise to 110 degrees Fahrenheit. Then try being a chimpanzee, an animal covered in hair but one that is smart enough to turn on a cold shower if only there was any running water around. But researchers have observed that Senegalese chimps do have a natural way to beat the heat — they duck into a series of cool caves when the temperature is unbearably hot.
The chimps of Senegal have been under observation for 20 years by primatologist Jill Pruetz of Texas State University and colleagues specifically because these apes have adapted to a harsh climate.
Most of the sites where chimps have been observed long term are forested areas in Central and West Africa. For example, Gombe Stream, the place where Jane Goodall first began her observations in 1960, is a forested ravine that slides into Lake Tanganyika. From Goodall and many others, we have come to understand how smart chimpanzees are, and how their social interactions echo human behaviors. The main reason primatologists have spent all these years observing chimps is to get a handle on what happened about seven million years ago when some chimpanzee-like line separated into two paths that eventually became today’s distinct lines of humans and chimpanzees.
Anthropologists know that for most of human history humans were hunters and gatherers and much of that happened on the wide savannahs of Africa. And so, the Senegalese chimps have risen in academic importance because they might provide clues about what it takes to survive and thrive in a savannah environment with its lack of trees, flat endless distances, and more arid climate.
Years of observation have shown that savannah chimpanzees lead hard lives; they are always searching for food and water, and they try to deal with the heat. During the rainy season, the chimps are attracted to natural pools and spend time lazing around in the water. Pruetz’s colleague Boyer Ontel, a professor at Ball State University, was also interested in their penchant for visiting a series of stone caves. Turns out when it’s 110 degrees outside, it’s about half as hot in the caves, as if someone had installed air conditioners. Ontel set up a camera at the mouth of one giant cave and took pictures on 365 days over a three-year period. He captured chimps going in and out of the cave on 45 occasions. More surprising, most of the visitors were adult females carrying infants. Males were hardly ever there and only a smattering of young chimps took advantage of the cool space.
But what makes this story so endearing, and eerily familiar, is that the mother chimps arrived with snacks and they let the babies play with each other while the mothers socialized. A play date, in other words, and one that gave a chilly respite for mothers and babies alike. But their particular tot spot was not without dangers. Ontel also recorded a leopard chasing chimps away on one occasion, but the mothers came back later and took over the space once the big cat was gone.
Just like human mothers who gather at the library or a coffee shop to claim some comfortable territory for themselves, female chimpanzees have been finding a place where they can comfortably mingle while letting their babies hang out with their peers.