Our genus Homo has been around for more than a couple of million years, and archaic forms of Homo sapiens for half a million or so.

The rapid expansion of anatomically modern humans out of Africa apparently corresponds in time with the invention of new techniques of stone tool making.

Besides the production of long, narrow flake tools, called blades, which can be fashioned into a variety of handy small tools, the new technology includes artifacts of bone and ivory, and eventually, clothing-often sewn together and decorated with beads.

These innovations, which especially define the Upper Paleolithic period, differentiate the stone tool culture of H. sapiens sapiens from the heretofore-similar cultures of the contemporary Neanderthals and other "archaics."

The Upper Paleolithic Period, the third and last subdivision of the Paleolithic or Old Stone Age, dates very broadly to between fifty thousand and ten thousand years ago, roughly coinciding with the appearance of behavioral modernity and before the advent of agriculture.

It is characterized by the emergence of regional stone-tool industries, such as the Perigordian, Aurignacian, Solutrean, and Magdalenian of Europe, as well as other localized industries of the Old World and the oldest known cultures of the New World.

Principally associated with the fossil remains of such anatomically modern humans as Cro-Magnons, Upper Paleolithic industries exhibit greater complexity, specialization, and variety of tool types and the emergence of distinctive regional artistic traditions.

We moderns were the only humans left standing by about 33,000 BCE, the red-haired Neanderthals having been replaced by our Cro-Magnon ancestors, who either absorb the former or defeat them in the competition for survival.

According to an study led by Dr Rosalind Harding, of the Institute of Molecular Medicine at the John Radcliffe Hospital, Oxford, the melanocortin 1 receptor gene for red hair was present one hundred thousand years ago-at least seventy thousand years before Homo sapiens' migration into Europe from Africa. Harding maintains that the gene could not have originated in the sweltering heat of Africa, because natural selection would not have allowed the survival of a trait that predisposes humans to skin cancer. Harding believes that the prevalence of the so-called "ginger gene" in so many of today's population provides evidence that early Homo sapiens bred with the Neanderthals and that many of today's humans are descended from unions between the two species.)

Evidence from a few sites indicates that Neanderthals coexisted for several thousand years with the modern humans (i.e., Cro-Magnons) that were living in Europe by thirty-five thousand years ago.

The nature of the Neanderthals' demise is no better understood than that of their evolutionary origins.

They were certainly replaced by Cro-Magnons, but whether they were absorbed by the Cro-Magnons or simply died out in competition with them is unknown.

Moderns live on six of the seven continents by 28,000 BCE, and have learned to make beautiful paintings and engravings.

The continents are essentially in their twenty-ninth century position, but larger, as global sea levels are lower, presumably due to locked-up water in the ice sheets.

The bow and arrow, which allows hunters to attack their prey from a secure distance, has probably been invented by the twelfth millennium, and our successful domestication of dogs marks the first instance of human cooperation with another species.