In this long history of accelerating development, one can single out two especially significant jumps. The first, occurring between 100,000 and 50,000 years ago, probably was made possible by genetic changes in our bodies: namely, by evolution of the modern anatomy permitting modern speech or modern brain function, or both. That jump led to bone tools, single-purpose stone tools, and compound tools.
The population that I already mentioned as having the world’s lowest recorded salt intake, Brazil’s Yanomamo Indians, also had the world’s lowest average blood pressure, an astonishingly low 96 over 61.
Protein starvation is probably also the ultimate reason why cannibalism was widespread in traditional New Guinea highland societies.
1. Acknowledgment that one is in crisis.
Table 1.1. Factors related to the outcomes of personal crises 1. Acknowledgment that one is in crisis 2. Acceptance of one’s personal responsibility to do something 3. Building a fence, to delineate one’s individual problems needing to be solved 4. Getting material and emotional help from other individuals and groups 5. Using other individuals as models of how to solve problems 6. Ego strength 7. Honest self-appraisal 8. Experience of previous personal crises 9. Patience.
10. Flexible personality 11. Individual core values 12. Freedom from personal constraints.
Larger populations mean more inventors and more competing societies.
I do not mean to imply, however, that the role of disease in history was confined to paving the way for European expansion. Malaria, yellow fever, and other diseases of tropical Africa, India, Southeast Asia, and New Guinea furnished the most important obstacle to European colonization of those tropical areas.
WEIRD: from Western, educated, industrialized, rich, and democratic societies.
The shift from hunting-gathering to farming began only about 11,000 years ago; the first metal tools were produced only about 7,000 years ago; and the first state government and the first writing arose only around 5,400 years ago. “Modern” conditions have prevailed, even just locally, for only a tiny fraction of human history; all human societies have been traditional for far longer than any society has been modern.
The first state arose in the Fertile Crescent around 3400 BC, and others.
Thus, the crops and animals of the Fertile Crescent’s first farmers came to meet humanity’s basic economic needs: carbohydrate, protein, fat, clothing, traction, and transport.
Our modern acorn squashes and summer squashes are derived from those American squashes domesticated thousands of years ago.
Allende had good ideas, but he executed them poorly. Although he correctly recognized Chile’s problems, he adopted wrong solutions to those problems.
A mere dozen species account for over 80 percent of the modern world’s annual tonnage of all crops. Those dozen blockbusters are the cereals wheat, corn, rice, barley, and sorghum; the pulse soybean; the roots or tubers potato, manioc, and sweet potato; the sugar sources sugarcane and sugar beet; and the fruit banana.
Farmers tend to breathe out nastier germs, to own better weapons and armor, to own more-powerful technology in general, and to live under centralized governments with literate elites better able to wage wars of conquest.
Because diseases have been the biggest killers of people, they have also been decisive shapers of history. Until World War II, more victims of war died of war-borne microbes than of battle wounds. All those military histories glorifying great generals oversimplify the ego-deflating truth: the winners of past wars were not always the armies with the best generals and weapons, but were often merely those bearing the nastiest germs to transmit to their enemies.
If we find people virtuous or admirable in one respect, it troubles us to find them no so in another respect. It is difficult for us to acknowledge that people are not consistent, but are instead mosaics of traits formed by different sets of experiences that often do not correlate with each other.
Against other illnesses, though – including measles, mumps, rubella, pertussis, and the now defeated smallpox – our antibodies stimulated by one infection confer lifelong immunity. That’s the principle of vaccination: to stimulate our antibody production without our having to go through the actual experience of the disease, by inoculating us with a dead or weakened strain of microbe.
In an epidemic those people with genes for resistance to that particular microbe are more likely to survive than are people lacking such genes. As a result, over the course of history, human populations repeatedly exposed to a particular pathogen have come to consist of a higher proportion of individuals with those genes for resistance – just because unfortunate individuals without the genes were less likely to survive to pass their genes on to babies.