CHIMP WATCHERS in East Africa have a theory about an odd piece of behaviour
that seems to narrow the gap between chimps and humans still further: the
animals may treat themselves when they feel sick with the same plants that
local people use for the same sort of illnesses.
Over the past decade, a number of reports in scientific journals have
hinted that chimpanzees seek out certain leaves and seeds for their physiological
or pharmacological effects. Although there is still no direct evidence that
a particular plant has a specific effect, three leading primatologists have
found the strongest circumstantial evidence so far that our primate cousins
treat themselves for a range of ailments.
Since the early 1970s, Richard Wrangham, professor of anthropology at
Harvard University, and Jane Goodall, the most famous of the chimp watchers,
have recorded in detail the behaviour of chimps as they foraged in the Gombe
Stream National Park in Tanzania. In the Mahale Mountains National Park,
south of Gombe, Toshisada Nishida, a zoologist at the University of Kyoto,
has made similar observations of chimps’ feeding behaviour. The scientists
recorded what the chimps ate every day, and at what time of day: at Gombe,
they catalogued 146 species in the diet; at Mahale, the chimps ate plants
belonging to 198 species.
The main focus of their studies is one genus of plant, Aspilia, which
chimps eat only rarely. There are several species of Aspilia throughout
Africa’s grasslands. The plants are tall but rather nondescript members
of the sunflower family. They caught Wrangham’s attention because he had
never seen any animal behaving as strangely as the chimps at…
