Remember the Savannah chimps I wrote about last week, who use spears to hunt bush babies? I was reading up on these chimps to prepare myself for their inevitable uprising and found research showing they do something else often associated with human evolution: cave dwelling.
Despite the name Savannah chimps don’t live in the classic grassland Savannah. They actually inhabit nearby forests, which is still a unique chimp environment. Most prefer to live much deeper into the jungle. However, even though they don’t live on the open plains the temperatures there can still reach scorching heights. 38 degrees is the point at which heat becomes a problem for chimps and the forests can reach this during the hottest months (May & June). However, the nearby Sakoto cave stays much cooler at a balmy 29 degrees or so.
In 2007 a researcher found hair, faeces and other evidence of chimp presence in this cave during the hottest period of the year. They put 2 + 2 together and concluded that the chimps were likely seeking refuge from the heat. Evidence of chimp occupation was found for nearly half the weeks of May and June. However, no direct observations were made. Without more data its difficult to figure out just how regular or important this behaviour is.
I do not envy the job of the researcher who has to go looking for spear-wielding chimps in dark caves to gather this extra data.