Most scientists who study our ancestors on the evolutionary ladder place the advent of truly modern human beings a few tens of thousands of years ago, during the last ice age. It was then that prehistoric Homo sapiens displaced their larger, brow-ridged cousins, Homo neanderthalis, throughout Europe. The rationale for equating this event with the ascendance of modern humans—and the modern human intellect—rests, in part, on the quantity and sophistication of paintings found in certain grottoes. Impressive examples of these ice-age art collections adorn such places as the Lascaux, Cosquer and Chauvet caves in southern France.
Surely such accomplished naturalistic artwork must represent the final flowering of the human mind. Surely it demonstrates the attainment of mental faculties comparable to those of people today. Surely it signals the evolution of a culture, with its rites, symbols and language, all perhaps as complicated as our own. Or perhaps not, according to Nicholas Humphrey in a controversial article that appeared last year in the Cambridge Archaeological Journal.
Humphrey, an evolutionary psychologist at the New School for Social Research in New York City, based his challenge to the accepted wisdom of anthropology on an observation he happened to make while examining the roots of expressionism (artwork that aims to reproduce the subjective emotions of the artist rather than to depict objective reality). For that study, Humphrey had pulled from his shelf a two-decade-old book about Nadia, a well-known autistic child with extraordinary drawing ability. Examining the young girl's renderings of horses and cows, "I suddenly thought 'I've seen these before,'" recounts Humphrey. So from a different part of his library, he grabbed a copy of the lavishly illustrated Dawn of Art, which describes the Paleolithic drawings of animals discovered in the Chauvet cave in 1994.
Humphrey quickly discovered that both Nadia and the paleolithic painters at Chauvet were fond of drawing horses, that both drew in perspective and that both exhibited certain odd peculiarities of style. For example, one picture is often blithely overwritten by another. Nadia and the Chauvet painters also shared a willingness to let their starting subject morph into a different animal, producing what appear to be pictures of chimera.
The similarity of Nadia's sketches and the ice-age murals of Europe inspired Humphrey to point out the correspondence in the pages of the scholarly journal. There he argued that well-executed naturalistic art should not be used as evidence of high-level conceptual thought, sophisticated symbolic communication or well-developed language. Young Nadia, he noted, hardly spoke at all and showed little interest in communicating with those around her. Yet her drawing ability, even as a small child, rivaled that of the best ice-age Picassos.
Humphrey also proposed that the realism displayed in the Paleolithic cave paintings might, in fact, indicate that the ice-age artists lacked the ability to speak as well as people do today. Competition in the brain between spatial and language aptitude could mean that devoting fewer neurons to language in the ancient past gave our ice-age forebears greater skills in drawing.
Following this line of reasoning, Humphrey supposes that the ice-age artists had only primitive language, employing it largely as a means of maintaining social bonds, a notion that others have suggested before. But Humphrey claims to see evidence for this limited scope: Using language only to talk about people would, he posits, have interfered with the artists' ability to draw people—neatly explaining why these cave paintings rarely show human forms as anything other than stick figures.
The publication of Humphrey's thesis sparked plenty of criticism, some of which was published alongside the original article. (According to Chris Scarre, editor of the Cambridge Archaeological Journal, contentious papers are routinely given such elaborate treatment.) Some of Humphrey's detractors said that it was dangerous to base a general conclusion about human nature on a single child. Others had difficulty imagining that language could have evolved to the point that people talked about one another but not about all subjects. Still others pointed out that Humphrey's analysis neglected the existence of archaeological artifacts showing symbolic notation.
Perhaps the most pointed assault on Humphrey's idea comes from quarters not well represented in the published critique. For example, Terrence Deacon, a neurobiologist at Boston University, says that any argument about the evolution of language that depends on archaeological evidence alone is flawed. The only place to find a record of the emergence of language abilities, Deacon asserts, is in the evolving anatomy of the brain and larynx. After all, he notes, many primitive communities in existence now leave little evidence behind that their members can speak and think every bit as sharply as people in highly developed societies.
Humphrey is happy to entertain such criticism: "The absence of evidence isn't evidence of absence, I agree." And he fully accepts that his ideas about language at the end of the ice age are quite speculative—expressing some reservation about whether he really believes them himself. But even if nothing can be proved either way, this psychologist is happy just to have stirred things up within the archaeological community with his playful musings. He quips, "I'm flying a kite here."—David Schneider