On a grassy slope above the shore of Lake Tanganyika in the east African nation of Tanzania, two male chimpanzees spot a hole in the ground, into which a long column of ants is marching. The chimps pause for a moment beneath the light drizzle of an early morning rain and then amble to the hole—the entrance to the ants' nest—for a closer inspection. The chimpanzees, lifetime residents of Tanzania's Gombe Stream National Park, expertly select several long sticks and sit down beside the nest. Slowly, each of them extends a stick into the hole and watches as some of the ants swarm up the probe. As soon as either of the chimps gauges that the lower half of the stick has become covered with ants, he extracts it from the nest. He then quickly gathers the tasty insects from the stick with his free hand and pops them into his mouth.

Across the continent in the Tai Forest of western Africa's Ivory Coast, two other male chimps have also discovered a nest of ants. They each find a suitable tool—a short stick, rather than the long probes favored by the Gombe chimps-and begin dipping it into the nest entrance to fish for a meal. After the ants guarding the nest climb up the sticks, the chimps sweep the sticks directly across their smacking lips and, without using their hands, draw the ants into their mouths.

At the same time that the chimps are enjoying their morning snacks, two other mealtime rituals are being played out by other primates (the order of mammals that includes humans, apes, and monkeys) far to the west. In St. Louis, Missouri, two human families—one whose ancestors came from Asia and the other whose forebears originated in Europe—sit down to dinner at separate tables in a Chinese restaurant. Both families order their favorite dish of spicy orange chicken. When the food is served, the Asian family begins eating its meal with chopsticks, while the other family picks up forks.

Since the dish could be eaten with either chopsticks or forks, the preference for one type of utensil over another is simply a reflection of cultural differences between the two families. There's nothing unusual about that. But what about the differences in the ways the Gombe and Tai chimpanzees perform ant fishing? Could those individual preferences also reflect differences in culture? Since all of the chimps are of the same species, it is unlikely that genetic differences could account for the variations in behavior. Thus, the different approaches to a similar task, ant fishing, are likely to be learned behaviors within the Gombe and Tai social groups. That means that knowledge may have been passed from one chimp to another. In other words, the chimps seem to be exhibiting behavior that could be called culture.

Social scientists have long maintained, however, that only humans are capable of possessing culture. Are they wrong? Do chimpanzees—and perhaps even other animals, such as monkeys, whales, and birds—also possess a form of culture? Many scientists in 2000 believed that the answer to that question is yes. But others insisted that culture is a purely human phenomenon.