The Dawn of Modern Culture

70,000-50,000 YEARS AGO

A fierce and sudden volcanic winter descended upon the earth sometime around 71,000 years ago, when Mt. Toba, an enormous volcano on the island we know as Sumatra, in the Andaman Sea, exploded in the largest surface eruption that the earth has known for the past 400 million years. The mountain's ash and debris shot at least twenty miles into the air and were eventually scattered worldwide: 480 square miles of ash, it is reckoned, settled over the earth, burying all of the Pacific islands and the Indian subcontinent under a coat of as much as 10 inches of heavy sediments and darkening the skies around the globe with more than an incredible 1.1 billion tons of stratospheric dust and sulfuric acid aerosols. All that remained behind was a huge caldera, the largest natural lake in southeast Asia, 60 miles long and 36 miles wide.

Temperatures plunged. Michael Rampino, a geologist at New York University, has figured that the drop must have been about 15 to 25 degrees Fahrenheit worldwide, maybe 75 degrees in higher latitudes, wiping out many plants in the tropics and as much as two-thirds of them in some temperate climates, and resulting in summers at least 15 degrees cooler and winters even worse. Minute ash particles raining from the sky would have penetrated the lungs of many animals, impairing breathing, and settled in the feathers of birds, making flight impossible. Ice core records show that the sulfuric acid haze persisted in the atmosphere for six years, reflecting the sun's rays and keeping the earth in a perpetual winter. It was followed by a severe mini-ice age that lasted for as long as a thousand years, probably the coldest period of any during the final 60,000-year Ice Age that it ushered in. Northern forests became treeless moss-and lichen-covered tundra over permanently frozen earth or semiarid grasslands dotted with stunted shrubs, while tropical rainforests turned into dry open savanna, and grasslands into wind-swept deserts.

The results for the hominid species then on earth would have been catastrophic. Some remnant populations of Homo erectus were living in Indonesia and China, and a certain number of those not in the immediate vicinity of the ignimbrite lava flow would have survived, especially in the more tropical areas, but their populations, also affected by ash particles and now dependent mostly on a diminished animal supply and cold-water shellfish, would have dropped severely. The Neandertals of Europe and the Levant, with bodies already adapted to the cold and millennia of experience with cold-weather survival, would have fared better, but their food supplies would have dwindled too and the northern populations were probably hit far harder than the Mediterranean ones. And in Africa, where modern Homo sapiens populations lived, only those in a few favorable pockets not made unlivable by the extremely cold and dry conditions—such as in coastal southern and eastern regions and along the Mediterranean, where water was available and marine food supplies adequate—could have resisted the volcanic winter.

An increasing number of new fossil finds suggest that it was at this point, and most likely in response to these sudden extreme conditions, that the surviving Sapiens populations began to develop, or more aggressively adapt, both cultural and psychological mechanisms that turned them into fully modern beings.

Homo sapiens had been modern in body for maybe 90,000 years by then: the earliest fossils of what are called "anatomically modern humans" have been found at some two dozen sites in Africa and two in the Levant (southwestern Asia but then geographically and climatologically an extension of Africa), the earliest at the Kibbish Formation in Ethiopia, dated to about 195,000 years ago. Whether this speciation process creating Homo sapiens was a relatively rapid event, as some paleontologists of the Stephen Jay Gould school argue, or a more gradual development out of Homo erectus and what is sometimes called "archaic Homo sapiens," as I am inclined to think the record shows, there is no doubt that some time around 150,000 years ago modern humans, fully erect, gracile in form and face, existed in Africa, with braincases in the range of 1,400-1,550 cubic centimeters (living human brains average about 1,350-1,400 cc.).

But it has been difficult to determine if these early Sapiens were modern in culture — that is to say, in day-to-day behavior, in artifacts, in social units that would be generally recognizable to us today—or rather still used the tools and thought the thoughts of their ancestors. The general record (which is not very replete in Africa and difficult to date in the range of 250-127,000 years ago) indicates that for the most part the kinds of tools associated with these modern people were old-fashioned ones that had been in use, both in Africa and Europe, for the preceding 100,000 years. In a few places, it is true, as recent discoveries are showing, there were flashes of modern culture of the kind that would come to characterize the later fossil record. In Katanda, for example, a site in the eastern Congo on the Semliki River, eight whole or partial barbed stone harpoons and four worked bone artifacts have been dated to 90-80,000 years ago (though with a range of probable error that could extend the most recent date forward to 71,000 years), providing the first clear evidence of Africans fishing in a concerted way and one of the earliest examples of the use of bone, and not just stone, to create weaponry. (Two earlier sites, Mumbwa and Broken Hill caves in Zambia, have bone fragments "puta-tively," but not convincingly, suggested as tools.) And in two sites in Tanzania, pieces of obsidian dated to 130,000 years ago have been found that originally came from the Rift Valley in Kenya, nearly 200 miles away, suggesting either a long-distance trading network or long-distance transport of valuable materials, both hallmarks of the later modern culture. But these exceptions only serve to underscore that for the most part these early Sapiens were a people, as the anthropologist Richard Klein of Stanford University has put it, "similar to their precursors but very different from their successors."

Then, about 70,000 years ago, something changes. A modern culture begins to emerge.

It is my thesis that under the pressure of trying to survive the sudden and harsh volcanic winter, these Sapiens had to expand their means of wresting a living from nature in a dramatic way, leading to the kind of practices that would afterwards mark the species for the rest of the Stone Age—and indeed, in most ways, down to the present. Or, to put it another way, it was those humans who either developed or adapted in this modern way, with a culture centered on the regular hunting of a great variety of species, crafting better tools, creating new weapons from a wider set of materials, and developing rituals for tribal cohesion, who were able to survive in these harsh conditions. It is after all a basic principle of...