| 2. Co-existence of multiple human species |
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KOBAYASHI: As I understand, human species that evolved in Africa eventually migrated all over the earth. The reason for that migration lay, in my opinion, in the strong sense of curiosity innate to human species. For instance, when a baby is born, it gives out a loud birth cry. But hardly has the cry subsided before the baby starts looking around its environment. Don't you think that humans are born information seekers? Couldn't you say that perhaps humans might have migrated, driven by sheer curiosity, rather than by climatic fluctuations, to find out what was going on where the sun rose? BABA: Well, your sunrise theory intrigues me, but I'm afraid that humans migrated not only to the east, but also to the west. First, bipedalism facilitated locomotion. Second, perspiration innate to humans dissipated heat like a cooling system to facilitate locomotion over a long distance. Finally, though humans are naked, they can withstand cold fairly well by storing subcutaneous fat. In other words, humans are better equipped to control body temperature than other animals. Such environmental adaptability was possibly a factor that helped humans extend their scope of activities. KOBAYASHI: So early Homo moved around far more extensively than we assume. BABA: Until about 10 years ago, it was believed that Homo erectus originating in Africa migrated all over the world and eventually evolved into Homo sapiens in each region they went to. Today, such a hypothesis is nearly extinct. The fact is, not only Australopiths, but also Homo erectus, archaic Homo sapiens or Neanderthals as well as late Homo sapiens, all originated in Africa, and each of them individually spread worldwide. As it took them several thousands of years to migrate, by the time they finally reached the land's periphery, a new human species might have arisen in Africa, replacing the old ones. |
