The uncertainty and confusion over the origin of modern cultural behavior stem from what appears to be a great time lag between the point when the species first looked modern and when it acted modern. Perhaps the first modern Homo sapiens emerged with a capacity for modern creativity, but it remained latent until needed for survival.

''The earliest Homo sapiens probably had the cognitive capability to invent Sputnik,'' said Dr. Sally McBrearty, an anthropologist at the University of Connecticut. ''But they didn't yet have the history of invention or a need for those things.''

Perhaps the need arose gradually in response to stresses of new social conditions, environmental change or competition from nonmodern human species. Or perhaps the capacity for modern behavior came late, a result of some as yet undetected genetic transformation.

Dr. Mary C. Stiner, an archaeologist at the University of Arizona, said those contrasting views, or variations of them, could be reduced to this single question: ''Was there some fundamental shift in brain wiring or some change in conditions of life?''

Sudden Genetic Advance

The foremost proponent of the traditional theory that human creativity appeared suddenly and mainly in Europe is Dr. Richard G. Klein, a Stanford archaeologist. He describes his reasoning in a new book, ''The Dawn of Creativity,'' written with Blake Edgar and being published next month by John Wiley.

''Arguably, the 'dawn' was the most significant prehistoric event that archaeologists will ever detect,'' the authors write. ''Before it, human anatomical and behavioral change proceeded very slowly, more or less hand in hand. Afterward, the human form remained remarkably stable, while behavioral change accelerated dramatically. In the space of less than 40,000 years, ever more closely packed cultural 'revolutions' have taken humanity from the status of a relatively rare large mammal to something more like a geologic force.''

In that view, 40,000 years ago was the turning point in human creativity, when modern Homo sapiens arrived in Europe and left the first unambiguous artifacts of abstract and symbolic thought. They were making more advanced tools, burying their dead with ceremony and expressing a new kind of self-awareness with beads and pendants for body ornamentation and in finely wrought figurines of the female form. As time passed, they projected on cave walls something of their lives and minds in splendid paintings of deer, horses and wild bulls.