The following are excerpts from some key points in this chapter:
○?This chapter will tell you that the continental axis has far-reaching influence and is even the source of human tragedies. The direction of the continental axis is related to the speed of the spread of crops and livestock, and also indirectly affects the spread of inventions such as writing and the wheel. The vastly different experiences of Native Americans, Africans, and Eurasians over the past 500 years are due to this basic geographical feature.
○?To understand the geographical differences and the relationship between guns, germs and steel, we must start with the spread of food production. There are at most 9, or maybe only 5, regions in the world that can develop their own food production industries. The main routes of spread of food production means are: from Southwest Asia to Europe, Egypt, North Africa, Ethiopia, Central Asia and the Indus River Basin, from the Sahel and West Africa to East and South Africa, from China to tropical Southeast Asia, the Philippines, Indonesia, Korea and Japan, from Central America to North America. Moreover, the origins of food production not only spread outward but were also enriched by the import of crops, livestock, and technology from outside.
○? The influence of geography on the difficulty of communication can be seen from what scholars call preemptive domestication. Most wild plants that later become crops will be genetically different from place to place, because wild populations in different areas accumulate different genetic mutations. Likewise, the transition from wild plants to crops could theoretically be triggered by different new mutations and different selection processes, resulting in crops that are more or less the same.
○?If we conduct genetic analysis on the major crops of the New World, we will find that many crops have two or more wild varieties. This indicates that the crop was domesticated independently in at least two places, and that some crop varieties have developed local characteristics.
○?The rapid spread of a certain crop may cause the crop’s wild ancestors elsewhere, as well as wild plants related to the ancestor species, to lose the chance to be domesticated again.
○?We can draw the same conclusion from various phenomena: food production spread out from Southwest Asia faster than the Americas, and probably faster than sub-Saharan Africa.
○?Why did crops spread so quickly in the Fertile Crescent? Part of the reason lies in Eurasia's east-west continental axis, the situation discussed at the beginning of this chapter. East and West, located at the same latitude, have the same day lengths and seasonal changes, similar diseases, similar temperatures and rainfall, and similar habitats and biomes.
○? The germination, growth and disease resistance of plants are closely related to the local climate. Phenomena such as day and night length, temperature and rainfall all affect seed germination, seedling growth and the flowering and fruiting of plants as they mature. Natural selection shapes the genetic code of every plant, and plants evolve under certain climatic conditions.
○? Part of the reason why domesticated animals in the Fertile Crescent spread rapidly east and west: These domesticated animals have long adapted to the climate of the introduced areas.
○? The spread of crops and livestock in the Fertile Crescent is comparable to that of the subtropical crops and livestock in southern China. These crops and livestock spread eastward, reaching tropical areas of Southeast Asia, the Philippines, Indonesia and New Guinea, with new crops and animals added along the way. Within 1600, this assemblage of crops (bananas, taro, and yams) and livestock (chickens, pigs, dogs) spread an additional 5,000 miles eastward, into the tropical Pacific and into Polynesia.
○? Latitude has been emphasized repeatedly, because at a glance at the latitude of a place on the map, you can know the climate, the growth environment of animals and plants, and the difficulty of agricultural spread. However, latitude is not everything. Two adjacent places located at the same latitude may not have the same climate pattern (although the length of the day is exactly the same). Topography and ecological barriers have a particularly pronounced impact on certain continents, thus making local spread difficult.
○?Although China is at the same latitude as the Fertile Crescent, it has developed its own food production industry and grows completely different crops. The barrier between China and western Eurasia was broken through in the penultimate millennium BC, when wheat, barley, and horses from West Asia were finally introduced to China.
○? Unlike crops, wheels and writing systems are not so directly related to latitude and day length.
These inventions are the product of the food production system and its influence, which can be said to be indirectly affected by latitude: the earliest wheels were part of oxcarts (oxcarts were used to carry agricultural products); the earliest writing was the patent of aristocrats (nobility dependent on farmers for support).
○? These reflect the differences between the Eurasian continental axis and the Americas and Africa, and the direction of the continental axis has long foreshadowed the fate of human history.
*Book information: [US] Jared Diamond, Wang Daohuan, translated by Liao Yuejuan, Guns, Germs and Steel [M]. Beijing: CITIC Press, 2022.