Fossil remains and genetic data suggest that modern humans come from Africa, and in the last decade anthropologists, archaeologists, linguists, and other scientists have tended to identify our species' biological origin with the origin of modern intelligence. The idea is quite simple. The process that produced our species in Africa granted it a number of advantages - syntactical language, advanced cognition, symbolic thinking - that favored its spread throughout the world and determined its eventual evolutionary success.
If, however, such advantages were dramatic and mainly determined by biological change, we should expect to find them reflected in the material culture produced by these early, anatomically modern populations. Complex technologies, regional trends in the style and decoration of tools, use of pigments, abstract and representational depiction, burials, grave goods, and personal ornaments are among the more common long-lasting creations that attest to the complex symbolic nature of ethnographically recorded human cultures.
Specifically, we should find such archeological evidence at sites in Africa from between 200,000 and 100,000 years ago. But what we see instead is a gradual emergence of behavioral innovations in and outside Africa between 300,000 and 20,000 years ago. Moreover, anatomically modern populations shared a number of these innovations with Neanderthals, which many anthropologists and geneticists consider a different species, or a human type inherently incapable of reaching our cognitive level.
For example, elongated stone blades are found not only at Neanderthal sites in Europe and the Near East, but also at sites inhabited by Moderns in the Near East and Africa since at least 100,000 years ago. Blade technologies then disappeared and reappeared cyclically in these areas, and in some regions, such as Australia, they only appeared a few thousand years ago.
Similarly, standardized tools produced by both Neanderthals and Moderns appeared 80,000 years ago. Pigments, probably used in symbolic activities such as tattooing or body painting, are found at Southern African sites since 300,000 years, but also at contemporaneous and more recent Neanderthal sites in Europe.
The intentional character and symbolic significance of burials prior to 30,000 years ago, especially those of Neanderthals, remain the subject of intense debate. But there is enough evidence to believe that both anatomically modern humans and Neanderthals began burying their dead 100,000 years ago - and probably before, as suggested by the recent dating at 160,000 years of a Neanderthal burial site at Tabun, Israel.
To be sure, sophisticated bone tools, such as harpoons, spear points, and awls, seem to have appeared in Africa 90,000 years ago, much earlier than in the rest of the world. This also applies to such artifacts of modern humans as personal ornaments, with recently discovered shell beads dated at 75,000 years ago.
But these innovations do not seem to have been widespread. Bone tools and beads are virtually absent from sites in Africa and the Near East inhabited by modern humans beginning 100,000 years ago, and few abstract engravings on bone and on fragments of ochre are found at African sites dated to 75,000 years ago. Depictions of animals, human beings, and other natural features do not occur in the three records - Africa, Europe, and the Near East - before 40,000-30,000 years ago, and they appear much later in some areas than others.
In sum, certain behavioral innovations seem to appear in Africa between 10,000 and 30,000 years before Neanderthals express them. But I doubt that this gap is evidence of different cognitive abilities. After all, it took 7,000 years for agriculture to arrive in England from the Near East, and nobody would argue that the cognitive abilities of Mesolithic hunter-gatherers from England were inferior to those of early agriculturalists.
This suggests that the trajectory of we "moderns" in our transformations since the end of the Ice Age has varied enormously in material culture. Future archaeologists would do well not to seek an explanation of this variation in terms of visible differences in our skeletal biology! "Modern" behavior may have appeared in different regions and among different groups of humans, much as would happen later in history with the inventions of agriculture, writing, and transport.
More fundamentally, behavior is certainly a significant component in determining a species' adaptation, geographic range, and mate-recognition system - all of which contribute to the maintenance of species boundaries. But this does not imply that modern behavior must have developed in a single species. Very close species may have similar behavioral systems and, in the case of our close predecessors, the shared features probably included many traits we have preferred to consider the monopoly of our species, including symbolic behavior.
The most important implication of believing that cultural modernity emerged in more than one species is that it largely eliminates the dichotomy that Western thought has traditionally detected between the natural world and human culture. The archaeology of early modern and Neanderthal populations suggests that we are not the chosen people who received from God the light, the divine mandate to go forth, multiply, and eliminate their subhuman neighbors.
This is a liberating, as well as a humbling, prospect. If the fact that we are the only human species left on earth is the result of an historical accident rather than Darwinian competition, we can open our minds and accept that we share some of our "culture" with both our living and no longer living relatives. Our modernity is probably a part of their legacy as well.