By JOHN TIERNEY
ATLANTA -- The chimpanzees, after spotting the humans at the corner of their compound, came over to us with their arms outstretched and their palms turned upward. This was the chimps' way of asking for a banana -- and a lot more, as researchers here at the Yerkes National Primate Research Center have discovered.
That simple gesture, the upturned palm, is one of the oldest and most widely understood signals in the world. It's activated by neural circuits inherited from ancient reptiles that abased themselves before larger animals. Chimps and other apes, notably humans, adapted it to ask not just for food, but also for more abstract forms of help, creating a new kind of signal that some researchers believe was the origin of human language.
If that's true, if human eloquence can be traced from a primal message signifying "Gimme," I'm not sure what conclusion to draw about our species. Maybe that we are inherently social creatures who survived and prevailed against mightier animals by learning to enlist the cooperation of others. Or maybe just that, in our heart of hearts, we are all slackers.
The meaning of the gesture is clear whether it's with one upturned palm, the "Brother, can you spare a dime" stance of beggars around the world, or with the two-palm version favored by preachers who reach out to beseech divine assistance. Or by exasperated Hollywood directors who rise from their chairs with upturned palms to implore their actors, "Work with me, people!"
The upraised palm is the automatic accompaniment to an apology or an alibi. As you try blaming the computer for eating your homework, you shrug your shoulders and expose your palms as a show of helplessness. What could I do? How could I know?
The palm-up gesture is what the anthropologist David Givens, director of the Center for Nonverbal Studies in Spokane, Wash., calls a "gestural byproduct" of the circuits in the brain and spinal cord that protected vertebrates hundreds of millions of years ago.
Confronted with a threat, ancient lizards would instinctively bend their spine and limbs to press their bodies closer to the ground, protecting the neck and head and signaling submission to a larger animal. This crouch display is the opposite of the high-stand display, the aggressive posture of a stallion or a gorilla raising its chest and head to appear larger.
The human remnant of the crouch display is a shrug of the shoulders, which lowers the head and rotates the forearms outwards so that the palms face up. Conversely, the high-stand display persists in humans as a rotation of the forearms and palms in the opposite direction, producing the domineering palm-down gesture used by a boss slapping the conference table or an orator commanding quiet from his audience.
Most of these gestures are performed unconsciously, but the palm-up was adapted long ago for conscious gestures by humans and other apes. Chimps and bonobos have been observed using it in the wild and in captivity. In a recent study, Amy Pollick and Frans de Waal, of Emory University, found that chimps here at Yerkes and bonobos in California used gestures in different ways depending on the situation and the group.
A chimp would use the palm-up gesture to ask other chimps to share food, for help in a fight, for sex or, most frequently, to request a grooming session. Bonobos used it most often as an invitation to play. The chimps and bonobos also sent signals through vocalizations and facial expressions, but these didn't vary much. They seemed to be more closely tied to emotions and weren't used as flexibly.
"These observations," Dr. Pollick said, "led Frans and me to speculate that gestures may have served as the steppingstone for early hominid communication and, possibly, language."
The primatologists at Emory note that gestures are controlled by the same part of the brain that controls speech. But it is also possible, they said, that gestures and speech evolved jointly to create language, as suggested by David McNeill, a psychologist at the University of Chicago.
Synchronizing gestures and speech was essential, Dr. McNeill believes, because what we see humans do today could not have arisen from a system of gesture-first pantomime.
As language evolved, humans used the palm-up for more complex ideas. They could signal, "I don't know," by holding both palms face up -- or cradling one upturned palm inside the other, a gesture North Africans use to mean, "I don't understand."
They could use the open palm metaphorically, as if it were holding an idea, to accompany an announcement like, "Here's my plan."
Chimps are not so subtle, but they can understand "Gimme" even when it's coming from nonchimps. Dr. Pollick found that that she could get a chimp to give her something by pointing to the object and making the palm-up gesture.
Even when the desired object wasn't visible, the chimps sometimes responded. When Dr. de Waal made the palm-up gesture to a chimp that had stashed some uncracked macadamia nuts inside her mouth, she knew exactly what he meant. She obliged him by gently spitting the nuts into his hand.
Watching the chimps at Yerkes, I began thinking of the palm-up as a sort of linguistic missing link, and it was comforting to think we still had some way to talk with our relatives. But this gesture has its limits for interspecies communication, as I realized when I tried making the palm-up gesture from the corner of the compound.
None of the chimps responded in any way. That wasn't surprising, if only because they don't normally respond to strangers. But even if they had wanted to, they would have been hard pressed to continue the conversation. They didn't have anything to give me, and they lacked a vital human skill: the ability to counter one palm-up with another.
They didn't know how to helplessly shrug their shoulders and hold out their empty upturned palms to send a sympathetic reply: I'd love to help you, buddy, but I'm all tapped out. Hominids learned to ask for favors early in their evolution. It took longer to figure out how to say a polite no.