After one session, Frans de Waal of Emory University said that as recently as a decade ago there was still no firm consensus on many of the social relationships of chimps. “You don’t hear any debate now,” he said.

In his own studies at the Yerkes Primate Research Center at Emory, Dr. de Waal found that chimps as social animals have had to constrain and alter their behavior in various ways, as have humans. It is a part of ape inheritance, he said, and in the case of humans, the basis for morality. The provocative interpretation was advanced in his recent book, “Primates and Philosophers.”

Other reports shortly before the symposium had elaborated on the abilities of chimps as toolmakers. Jill Pruetz, a primatologist at Iowa State University, described 22 examples of chimps in Senegal making stick spears to hunt smaller primates for their meat. Dr. Goodall was the first to call attention to chimps as hunting carnivores, not strictly vegetarians.

Dr. Pruetz observed several chimps jabbing the spears into hollow tree trunks where bush babies often dwell. Just one attempt was successful. Previously, chimps had been seen using sticks mainly to extract termites from their nests.

A team of archaeologists led by Julio Mercader of the University of Calgary reported finding stones in Ivory Coast that chimps used 4,300 years ago to crack nuts. Today’s chimps have often been videotaped using rocks as a hammer to open nuts. The old stones with starch residues from nuts, the researchers said, were the earliest strong evidence of chimp tool use, and the finding suggested that chimps had learned the skill on their own, rather than copying humans.

Other researchers combine field work showing chimp behavior in natural habitats with laboratory experiments that are created to disclose their underlying intelligence — what scientists call their “cognitive reserve.”

Image From the top, Ayumu, a 6-year-old male, shows foresight in stacking blocks; chimps can outperform humans at some memory tasks; they use simple tools like twigs to dig out ants and termites, and rocks to crack open nuts. Credit... From top, Estuko Nogami/Kyoto University; Tetsuro Matsuzawa; Michael K. Nichols/National Geographic; Estuko Nogami/Kyoto University

For example, chimps on their own would not sit at a computer responding with rapid touches on the screen as a test of their immediate memory. Videos of their doing just that at Kyoto University in Japan especially impressed the symposium scientists.