Page 304 - Earth's Climate Past and Future
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280     PART V • Historical and Future Climate Change



          IN SUMMARY, the overall outline of human evolution
          has gradually fallen into place, but the sparse fossil
          record makes it difficult to test hypotheses about
          the cause or causes of human evolution. As a result,
          the degree to which climate has affected human
          evolution is unknown.



        The Impact of Climate on Early Farming
        In almost 2.5 million years, hominins had moved only
        slightly beyond the most primitive level of Stone Age life,
        adding control of fire and gradually more sophisticated
        stone tools to a meager repertoire of skills. But once our  FIGURE 15-10 Early human buildings Humans living in
        species appeared, near 200,000 to 150,000 years ago, the  northern Asia during the last glaciation constructed domed
        pace of change quickened. By the time of the most recent  dwellings of hides draped over mammoth bones. Other bones
        glaciation, our ancestors painted amazingly lifelike por-  served as anchors.
        trayals of animals on the walls of caves and rock shelters
        (Figure 15–9). They also made small statues of human
        and animal figures and created jewelry by stringing  and colder near-Arctic latitudes. There they built dome-
        together shells, and they buried their dead with food and  shaped houses with large mastodon bones supporting
        possessions for use in a future life. In these changes, we  the superstructure and animal hides draping the roof
        can recognize the early origins of a true human “culture.”  for protection from rain and snow (Figure 15–10).
           More sophisticated stone tools designed for specific  People also learned how to make rope from naturally
        functions also appeared, and, for the first time, people  available fibers and used the rope to make snares and
        began to use bone, a much more “workable” substance  lines and nets to catch small animals, birds, and fish. The
        than stone, yet hard enough for many uses: as needles,  hunting-gathering life became a hunting-gathering-
        awls (hole-punchers), and engraving tools. Needles  fishing life. People shaped bone into spear throwers that
        made possible sewn clothing that fit closely, rather than  held stone spear points and used rope to help bind the
        loosely draped animal hides. With greater protection  spear points to the shafts. This new technology pro-
        from the elements, people pushed northward into higher  duced a lethal and revolutionary new way of hunting
                                                            that combined a weapon that could kill efficiently with a
                                                            hand that could grasp it and an arm with the natural
                                                            range of motion to throw it. Hunters could now bring
                                                            down larger game—even mammoths—from a safer dis-
                                                            tance, as cave paintings show. By the start of the present
                                                            interglaciation, an explosive alteration of basic human
                                                            existence was underway.

                                                            15-4 Did Deglacial Warming Lead to Early
                                                            Agriculture?
                                                            The first evidence of agriculture dates to just over
                                                            12,000 calendar years ago in a region of the Middle East
                                                            called the Fertile Crescent, encompassing present-day
                                                            Syria, Iraq, Jordan, and Turkey. The people living in
                                                            this region (called Natufians) abandoned the hunting-
                                                            and-gathering way of life and began to cultivate wheat,
                                                            rye, barley, peas, and lentils rather than harvesting
                                                            grains growing in the wild. Because agriculture elimi-
        FIGURE 15-9 Cave painting of the glacial era Despite the  nated the need for seasonal migrations to search for
        harsh glacial climate, our ancestors left beautiful, almost  food, these people took up residence in permanent
        modern-looking paintings on the walls of caves in southern  dwellings. Within 1000 years, the dwellings began to
        Europe. (Ferrero/Labat/Auscape International.)      cluster into permanent village settlements.
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