National Geographic : 1958 Aug
How Old Is It? of oxygen-18 when the climate is warm than when it is cool. Dr. Emiliani's cores give striking evidence of strong oscillations in world temperature. And the curves he has drawn to show these fluctuations closely parallel the picture of glacial retreats and advances sketched by radiocarbon, varve, and pollen studies. Man Becomes a Farmer A second contribution of the new dating techniques is to extend our knowledge of the beginning of agriculture back an additional 2,000 years. For this we can thank Dr. Robert J. Braidwood, of the University of Chicago's Oriental Institute, who has exca vated, in the Kurdish hills of northern Iraq, the earliest known agricultural village. Its name is Jarmo, and its radiocarbon age is about 9,000 years, determined just a few months ago by Washington's Geological Sur vey laboratory. "Some 4,000 years before historic times, Jarmo's people grew barley and two kinds of wheat," says Dr. Braidwood. "They made flint sickles with which to reap their grain, milling stones on which to crack it, and ovens in which to parch it. We are sure they had the domesticated goat, and possibly also sheep, pigs, dogs, cattle, and horses. They left behind an astounding variety of brace lets, magnificent stone bowls, and figurines." Why should a forgotten mud town like Jarmo be important to us today? Because civilization was not possible until man gave up hunting and the gathering of wild food as a way of life, settled on the land, and learned the time-saving skills of agriculture. The time at which man first became a farmer is therefore regarded by scientists as the first truly crucial period in history, even greater in its impact than the industrial revolution. Only after this development do we see the appear ance of political organization, architecture, temples, public works, monumental art, and writing-the hallmarks of civilization. Early Man Comes to America The third major contribution of radiocarbon is the light it throws on the history of man in the New World. The first creatures who could be called human presumably lived in Africa or south eastern Asia. There we find a few crude stone tools and extremely old fossil remains esti mated to be roughly half a million years old. Apparently it took a very long time for Early Man to discover the bridge between Asia and the Americas and to cross the Bering Strait. Skeletal remains of ancient men in the Americas are so rare that it used to be a common notion that the Indians had been in the New World only a few centuries before Columbus. As recently as the 1930's, so well known an anthropologist as Ales Hrdlieka scoffed at scientists who suggested that the In dians might have been here much earlier than the beginning of the Christian Era. If Dr. Hrdlicka were alive today, he would be forced to revise his views substantially. Radiocarbon says that men armed with stone tipped spears were hunting mammoth, bison, horse, and tapir in Arizona at least by 10,000 B. C., and quite possibly earlier. These early Americans were inhabiting Illinois's Modoc Rock Shelter by 8000 B. C. and Alabama's Russell Cave by 7000 B. C. They had pushed all the way to the Strait of Magellan, near the tip of South America, by 6700 B. C.* The dim beginnings of agriculture in the New World seem to go back beyond 4000 B.C., for primitive maize appears in New Mexico's Bat Cave with charcoal of that age. Ancient Copper Mines on Isle Royale How old is America's copper industry? Few would guess the answer: nearly 4,000 years. That long ago, charred wood tells us, aborig ines worked thousands of pits on Isle Royale, Michigan, in Lake Superior, now a national park. For at least a millennium these pre historic miners, who threw water on heated rock to crack loose the pure metal, traded their product as far south as Florida. Benjamin Franklin may well have known of the ancient mines when he arranged at the Treaty of Paris in 1783 for the boundary of the new United States to include Isle Royale. One somewhat controversial radiocarbon date suggests an antiquity for aboriginal Americans of 35,000 B. C. and beyond. After recent excavations for a Trinity River dam at Lewisville, Texas, near Dallas, a number of "hearths" came to light. These consisted of circular patches of fire-reddened clay, which yielded quantities of charcoal and animal bones and a beautifully worked flint spear head. Two samples of the charcoal, tested at the Humble laboratory in Houston, showed so * See "Ice Age Man, the First American," by Thomas R. Henry, NATIONAL GEOGRAPHIC MAGAZINE, December, 1955.