ความคิดเห็นที่ 10
Let's next examine whether this scheme, derived from the collision of Europeans with Native Americans, helps us understand the broadest pattern of African history, which I'll summarize in five minutes. I'll concentrate on the history of sub-Saharan Africa, because it was much more isolated from Eurasia by distance and climate than was North Africa, whose history is closely linked to Eurasia's history. Here we go again:
Just as we asked why Cort?s invaded Mexico before Montezuma could invade Europe, we can similarly ask why Europeans colonized sub-Saharan Africa before sub-Saharans could colonize Europe. The proximate factors were the same familiar ones of guns, steel, oceangoing ships, political organization, and writing. But again, we can ask why guns and ships and so on ended up being developed in Europe rather than in sub-Saharan Africa. To the student of human evolution, that question is particularly puzzling, because humans have been evolving for millions of years longer in Africa than in Europe, and even anatomically modern Homo sapiens may have reached Europe from Africa only within the last 50,000 years. If time were a critical factor in the development of human societies, Africa should have enjoyed an enormous head start and advantage over Europe.
Again, that outcome largely reflects biogeographic differences in the availability of domesticable wild animal and plant species. Taking first domestic animals, it's striking that the sole animal domesticated within sub-Saharan Africa was [you guess] a bird, the Guinea fowl. All of Africa's mammalian domesticates ? cattle, sheep, goats, horses, even dogs ? entered sub-Saharan Africa from the north, from Eurasia or North Africa. At first that sounds astonishing, since we now think of Africa as the continent of big wild mammals. In fact, none of those famous big wild mammal species of Africa proved domesticable. They were all disqualified by one or another problem such as: unsuitable social organization; intractable behavior; slow growth rate, and so on. Just think what the course of world history might have been like if Africa's rhinos and hippos had lent themselves to domestication! If that had been possible, African cavalry mounted on rhinos or hippos would have made mincemeat of European cavalry mounted on horses. But it couldn't happen.
Instead, as I mentioned, the livestock adopted in Africa were Eurasian species that came in from the north. Africa's long axis, like that of the Americas, is north/south rather than east/west. Those Eurasian domestic mammals spread southward very slowly in Africa, because they had to adapt to different climate zones and different animal diseases.
The difficulties posed by a north/south axis to the spread of domesticated species are even more striking for African crops than they are for livestock. Remember that the food staples of ancient Egypt were Fertile Crescent and Mediterranean crops like wheat and barley, which require winter rains and seasonal variation in day length for their germination. Those crops couldn't spread south in Africa beyond Ethiopia, beyond which the rains come in the summer and there's little or no seasonal variation in day length. Instead, the development of agriculture in the sub-Sahara had to await the domestication of native African plant species like sorghum and millet, adapted to Central Africa's summer rains and relatively constant day length.
Ironically, those crops of Central Africa were for the same reason then unable to spread south to the Mediterranean zone of South Africa, where once again winter rains and big seasonal variations in day length prevailed. The southward advance of native African farmers with Central African crops halted in Natal, beyond which Central African crops couldn't grow ? with enormous consequences for the recent history of South Africa.
In short, a north/south axis, and a paucity of wild plant and animal species suitable for domestication, were decisive in African history, just as they were in Native American history. Although native Africans domesticated some plants in the Sahel and in Ethiopia and in tropical West Africa, they acquired valuable domestic animals only later, from the north. The resulting advantages of Europeans in guns, ships, political organization, and writing permitted Europeans to colonize Africa, rather than Africans to colonize Europe.
Let's now conclude our whirlwind tour around the globe by devoting five minutes to the last continent, Australia. Here we go again, for the last time.
In modern times, Australia was the sole continent still inhabited only by hunter/gatherers. That makes Australia a critical test of any theory about continental differences in the evolution of human societies. Native Australia had no farmers or herders, no writing, no metal tools, and no political organization beyond the level of the tribe or band. Those, of course, are the reasons why European guns and germs destroyed Aboriginal Australian society. But why had all Native Australians remained hunter/gatherers?
There are three obvious reasons. First, even to this day no native Australian animal species and only one plant species (the macadamia nut) have proved suitable for domestication. There still are no domestic kangaroos.
Second, Australia is the smallest continent, and most of it can support only small human populations because of low rainfall and productivity. Hence the total number of Australian hunter/gatherers was only about 300,000.
Finally, Australia is the most isolated continent. The sole outside contacts of Aboriginal Australians were tenuous overwater contacts with New Guineans and Indonesians.
To get an idea of the significance of that small population size and isolation for the pace of development in Australia, consider the Australian island of Tasmania, which had the most extraordinary human society in the modern world. Tasmania is just an island of modest size, but it was the most extreme outpost of the most extreme continent, and it illuminates a big issue in the evolution of all human societies. Tasmania lies 130 miles southeast of Australia. When it was first visited by Europeans in 1642, Tasmania was occupied by 4,000 hunter/gatherers related to mainland Australians, but with the simplest technology of any recent people on Earth. Unlike mainland Aboriginal Australians, Tasmanians couldn't start a fire; they had no boomerangs, spear throwers, or shields; they had no bone tools, no specialized stone tools, and no compound tools like an axe head mounted on a handle; they couldn't cut down a tree or hollow out a canoe; they lacked sewing to make sewn clothing, despite Tasmania's cold winter climate with snow; and, incredibly, though they lived mostly on the sea coast, the Tasmanians didn't catch or eat fish. How did those enormous gaps in Tasmanian material culture arise?
The answer stems from the fact that Tasmania used to be joined to the southern Australian mainland at Pleistocene times of low sea level, until that land bridge was severed by rising sea level 10,000 years ago. People walked out to Tasmania tens of thousands of years ago, when it was still part of Australia. Once that land bridge was severed, though, there was absolutely no further contact of Tasmanians with mainland Australians or with any other people on Earth until European arrival in 1642, because both Tasmanians and mainland Australians lacked watercraft capable of crossing those 130-mile straits between Tasmania and Australia. Tasmanian history is thus a study of human isolation unprecedented except in science fiction ๗ namely, complete isolation from other humans for 10,000 years. Tasmania had the smallest and most isolated human population in the world. If population size and isolation have any effect on accumulation of inventions, we should expect to see that effect in Tasmania.
If all those technologies that I mentioned, absent from Tasmania but present on the opposite Australian mainland, were invented by Australians within the last 10,000 years, we can surely conclude at least that Tasmania's tiny population didn't invent them independently. Astonishingly, the archaeological record demonstrates something further: Tasmanians actually abandoned some technologies that they brought with them from Australia and that persisted on the Australian mainland. For example, bone tools and the practice of fishing were both present in Tasmania at the time that the land bridge was severed, and both disappeared from Tasmania by around 1500 B.C. That represents the loss of valuable technologies: fish could have been smoked to provide a winter food supply, and bone needles could have been used to sew warm clothes.
จากคุณ :
Darksingha 
- [
29 มี.ค. 50 13:50:29
]
|
|
|
