The New Chimpanzee
The new chimpanzee in the world turns out to be one we've known all along.
Posted Mar 12, 2018
There’s a new chimpanzee in the world, and it turns out to be one we’ve known all along. Jane Goodall’s pioneering study in Gombe National Park, Tanzania, began in 1960, well over a half-century ago. She made historic discoveries about tool use, meat-eating, mother-infant bonds, reproduction, and violence in chimpanzee society. As the research stretched from years into decades, Goodall’s work provided the kind of key information on chimpanzee society that only comes with long-term longitudinal research. Other multi-decade field studies followed: in the nearby Mahale Mountains, led by Toshisada Nishida and in Bossou in the Republic of Guinea, established by Yukimaru Sugiyama. In 1979, Christophe Boesch observed chimpanzees in West Africa collecting stones and sticks from the forest floor, carrying them to the foot of large nut trees, and using their tools to hammer open hard-shelled fruits. He observed hunting behavior just as researchers at Gombe and Mahale had, but with more cooperation among the hunters.
As observations on wild chimpanzees accumulated from many sites over many years, a picture of rich cultural variation emerged. As researchers established new field studies, they also discovered new chimpanzee cultures, each with its own unique set of traditions. Today, the cultural behavior exhibited by Gombe chimpanzees is just one of many cultural variants observed in other long-term studies across equatorial Africa. There has been a tidal wave of awareness of cultural behavior since the late 1990s. Most cultural behaviors in chimpanzees seem quite trivial. Two Mahale chimpanzees clasp right hands above their heads while their left hands groom their partners. At Gombe, the grooming partners grasp branches instead of hands. In some forests, chimpanzees use small sticks to probe into tree bark for ants; in other forests they don’t, even though the same ants are readily available. As the number of long-term field studies of chimpanzees grew, so did the scope of cultural diversity across Africa. In the fourth decade of chimpanzee field research, Andrew Whiten of St. Andrews University compiled the full complement of cultural variation across Africa, using information contributed by co-authors from each of the seven longest-term studies. They identified 39 behaviors across seven sites that appeared to be culturally and not ecologically induced. These included both foraging and social traditions.
There are now seven field studies of chimpanzees that have stretched beyond 25 years. It takes many years and enormous effort to maintain a field study of chimpanzees for enough years to get a payoff of new observations. It’s a tremendous achievement by a small number of very dedicated individuals that so many studies have been carried out, despite hardships of funding, local political turmoil, and the general difficulties of field research. Each study offers new frontiers of research. At Fongoli in southeastern Senegal, a team led by primatologist Jill Pruetz of Iowa State University has recorded chimpanzees doing things that we had not suspected they would do. They sit in pools of water to cool off in hot weather (chimpanzees normally avoid even knee-deep water) and sleep in caves to avoid the baking heat. The Fongoli chimpanzees also invented a new use for stick tools: They ram them into holes in trees to bludgeon and disable unwitting bush babies, tiny primates which then become lunch.
Over the past 20 years, scientists have made dramatic discoveries about chimpanzees that will change the way we understand both human nature and the apes themselves. Although there is a rich history of chimpanzee field research going back nearly 60 years, exciting new findings have been made since the turn of the millennium. From mating to violence to cultural traditions, we now consider our closest kin in a new light and have exciting new information to improve our understanding of human nature.