From Guns, Germs, and Steel by Jared Diamond, 1999

In 1500, at the beginning of European colonialism, Europe, Asia, and north Africa had metal and were on the verge of industrialization, sub-Saharan Africa had some small states with iron tools, and the Aztec and Incan empires had bronze tools. The rest were Stone Age hunter-gatherers and farming tribes.

All humans were hunter-gatherers until 11,000 BC, the end of the last Ice Age. Then most of Eurasia and much of the Americas and sub-Saharan Africa began to develop agriculture, herding, metallurgy, and complex political organization, based on food surpluses. Each of these new developments appeared first in Eurasia, beginning in the Near East’s Fertile Crescent.

Plant and animal domestication led to food surpluses, which led to complex societies, which led to possession of the means of conquest and germs (originating in domestic animals). This sequence occurred around 8500 B.C. in the Fertile Crescent and a thousand years later in China. It was reached – with imported crops – in the Indus valley in 7000 BC, in Egypt in 6000 BC, in western Europe from 6000 BC to 3500 BC, and in the African sahel in 5000 BC. It didn’t happen in Mesoamerica until 3500 BC, or in the Andes, Amazonia, or eastern United States until 2500 BC.

What gave the Fertile Crescent its head start? To start with, the wild ancestors of its crops were abundant and highly productive, and cultivation required few changes (compared to corn, which took a thousand years to get where it is today). In addition, wheat, the Fertile Crescent’s basic grain crop, has a higher protein content than rice and corn. The Fertile Crescent also had the world’s greatest diversity of wild plant and animal species, including a high diversity of annuals, which make the best food plants. There were many wild grasses with large, heavy seeds, like its earliest important crops: barley, wheat, peas, and lentils. Big mammals available for domestication included goats, sheep, pigs, and cattle, all domesticated earlier than any other animal except the dog. Because of their domesticated animals, people in the Fertile Crescent had a lot more protein in their diet than other early agriculturalists. Large domesticated mammals could also be used for transport (including pulling plows) – another advantage. By 1800 BC horses were being used to pull battle chariots in western Asia. In 1074 BC they enabled the Hyksos to conquer Egypt. In the 1200s and 1300s AD Mongols on horseback conquered Russia and much of Asia. In addition, large domesticated animals provided meat, milk, fertilizer, leather, wool, and germs that could kill previously unexposed peoples.

Second, hunting and gathering were poor in this area, encouraging an earlier switch to agriculture.

Third, the Fertile Crescent’s range of altitudes allowed for staggered seasons and many crops.

In New Guinea agriculture developed in 7000 BC, but there were no large-seeded wild grasses to become cereal crops, and no pulses. Neither were there any domesticable large mammals (New Guineans only got pigs, chickens, and dogs in the last few thousand years). New Guinean highland farmers had a low protein diet of taro and, later, sweet potato.

In Mesoamerica there were only two domesticable animals, the turkey and dog, both with low meat yield and neither useful for transport. Even though corn was being cultivated thousands of years earlier, there were no settled villages here until 1500 BC.

Agriculture didn’t develop in the eastern United States until 2500 to 1500 BC. There were four seed crops: a squash, sunflower, sumpweed (a daisy relative), and goosefoot (a spinach relative), but these were only minor dietary supplements to hunting and gathering. Between 500-200 BC three more seed crops were developed: knotweed, haygrass, and little barley, grasses that have tiny seeds rich in protein and oil. Corn arrived from Mexico around 200 AD, but its role was minor until a variety adapted to North America’s short summers was developed around 900 AD. By 1100 AD, beans had arrived. The dog was the only animal domesticated in this area.

So, because of what was available in their environment, not because they were more intelligent, the peoples of the Fertile Crescent domesticated local plants much earlier than people elsewhere. For the same kinds of reasons, they were able to domesticate many more productive or valuable species, had a much wider range of crops, and developed intensified food production and dense human populations more rapidly. As a result, they entered the modern world with more advanced technology, more complex political organization, and more epidemic diseases with which to infect other people.

North America, sub-Saharan Africa, and Australia had no large domesticated animals. Eurasia had the major five – cow, sheep, goat, pig, and horse – and two kinds of camels, the donkey, reindeer, the water buffalo, and the yak. Southwest Asia had seven of these. South America had the llama and the alpaca.

Dates of domestication

Dog                                           10,000 BC Southwest Asia, China, North America

Sheep, goat                              8,000 BC Southwest Asia

Pig                                             8,000 BC Southwest Asia, China

Cow                                           4,000 BC Southwest Asia, India

Horse                                        4,000 BC Ukraine

Donkey                                     4,000 BC Egypt

Water Buffalo                          4,000 BC China

Llama/alpaca                           3,500 BC Andes

Bactrian (2 humped) camel  2,500 BC Central Asia

Arabian (1 humped) camel   2,500 BC Arabia

Another way that geography affected people around the world was that the axis orientations of the continents affected the rate of spread of crops, livestock, and culture. Eurasia has an east-west axis, where similar latitudes, climates, and types of vegetation allow similar crops to grow. Writing and the wheel spread rapidly (.7 mile a year) from the Fertile Crescent, reaching Europe, North Africa, central Asia, and the Indus Valley by around 3000 B.C.

Africa and the Americas have north-south axes, permitting only slow diffusion. Southwest Asian crops would have had to go through 2,000 miles of unsuitable tropical climates to reach South Africa, for example. Africans south of the Sahara grew sorghum and yams adapted to warm temperatures, summer rains, and constant day lengths. The spread of Fertile Crescent domestic animals to Africa was similarly slowed down by climate and disease, especially trypanosome diseases carried by the tsetse fly. The horse never went further south than west Africa’s kingdoms north of the equator, and cattle, sheep, and goats stopped at the northern edge of the Serengeti Plains. Bantu food production, on the other hand, spread quickly from the Great Lakes region to Natal because the intervening areas are suitable for agriculture and have similar rainfall.

Crops and domestic animals failed to spread between highland Mexico (the turkey) and the Andes (llamas, guinea pigs, and potatoes) because of hot intervening lowlands. Farming in the southwestern United States was similarly prevented from reaching California by intervening deserts. It took several thousand years for Mexican corn, squash, and beans to travel 700 north-south miles to the southwestern United States. In 900 AD hardy varieties of corn adapted to northern climates allowed the flowering of the Mississippian culture, the most complex of North America.

Farmers tend to breathe out nastier germs; own more powerful technology, including better weapons and armor; and live under centralized governments with literate elites able to wage wars of conquest.

The major killers of humanity in recent history – smallpox, influenza, tuberculosis, malaria, plague, measles, cholera, and HIV/AIDS – all developed from infectious diseases of animals. In order to develop and survive, diseases need a large, comparatively dense host population. Agriculture, cities, poor sanitation, and long trade routes allowed many of today’s diseases to thrive. Smallpox, which originated in Egypt in 1600 BC, reached Rome in 168 AD. Mumps developed in 400 BC, leprosy in 200 BC, epidemic polio in 1840 AD, and AIDS in 1959. The bubonic plague first appeared in Europe in 542 AD, but required the regular transit of flea-infested furs from plague-ridden areas of central Asia to hit full force, as the Black Death, in 1346.

Diseases often develop in large, dense populations of domesticated animals. The measles virus came from the rinderpest virus in cattle. Cattle also gave us tuberculosis and smallpox. Pigs and ducks gave us flu, pigs and dogs gave us whooping cough, and chickens and ducks gave us malaria.

Cortez and Pizarro – among the first European colonizers – came to the Americas in ships using the latest in European maritime technology, financed by Spain’s centralized political organization. They conquered the Aztecs and Incas with steel swords and other steel weapons; steel helmets and armor, including chain mail; horses (domesticated on the steppes north of the Black Sea in 4000 BC); and germs to which Native Americans had no immunity: smallpox, measles, and influenza. These epidemic diseases spread in advance of the Europeans, killing 95% of affected populations. One of these, the Mississippian chiefdoms, the most highly organized native society of North America, disappeared before Europeans even entered the area. The San of South Africa, Australian aborigines, and Pacific islanders were also decimated by European diseases at first contact.

The Spanish, who had fairly sophisticated knowledge about much of the world, used writing to transmit information quickly and completely. In contrast, Atahualpa, the Incan emperor, knew nothing about Spain’s conquest of central America, and had no way of understanding that Pizarro’s men formed the spearhead of a force bent on permanent conquest.

Smallpox paved the way for Cortez and Pizarro, killing half the Aztecs and a large proportion of the Inca population. The pre-Columbian New World population was not far below the contemporary population of Eurasia. North America, originally occupied by 20 million Indians, declined by 95% in the 100-200 years after 1492 because of smallpox, measles, influenza, typhus, diphtheria, malaria, mumps, whooping cough, plague, tuberculosis, and yellow fever.

The only New World domestic animal liable to be a disease source, llamas/alpacas, had four strikes against them as a source of human pathogens: they were kept in comparatively small herds, their total numbers were never as large as those of European livestock, people don’t drink llama milk, and llamas aren’t kept indoors.

The critical historical agents – germs, writing (developed in Eurasia in 3000 BC, China in 1500 BC, and Mesoamerica in 600 BC), technology, and government and religion – developed first in Eurasia.

Decision-making is egalitarian in the hunter-gatherer band, starts to veer toward the “big man” in the tribe, and becomes centralized in the hereditary chiefdom (almost always agricultural) and the more modern state. Bureaucracy can appear in the chiefdom. The chiefdom and state monopolize force and information. Conflicts are resolved informally in the band and tribe, in a centralized fashion in the chiefdom, and via laws and judges in the state. Religion is used to justify inequality in the chiefdom and state.

Tribes of a few hundred or less began to emerge 13,000 years ago in the Fertile Crescent with harvests of abundant wild cereals. Chiefdoms of several thousand to several tens of thousands arose in 5500 BC in the Fertile Crescent and in 1000 BC in Mesoamerica and the Andes. Chiefdoms feature hereditary rule and commoner classes and use slaves to do menial work. Reciprocal exchanges continue, but tribute is introduced, morphing into taxes in foodstuffs and labor. States (over 50,000 people) arose in 3700 BC in Mesopotamia, by 1 AD in the Andes, China, and southeast Asia, and in 1000 A.D. in West Africa. In states slavery was seen on a larger scale, there was defined territory, and kings were often divine.

Bands, tribes, and most chiefdoms consist of a single ethnic and linguistic group. States, especially empires formed by the amalgamation or conquest of states, are usually multiethnic and multilingual.