Quotes from Peter Turchin

We know that, over the past 10,000 years, larger polities consistently outcompeted smaller ones, with the result that 99.8 percent of people today live in countries with populations of one million or more.

It takes at least 100 human generations for agricultural societies to develop into states

But while Ashoka is unusual in his exceptional degree of care for the wellbeing of his subjects, he is not unique. In fact, he represents a new trend: all across Eurasia, rulers were getting interested in what today we would probably call social justice. In

Our oversized brains evolved, in large part, to detect and resist manipulation by those who want to get ahead at our expense.

We also know, of course, that human beings are not perfectly rational calculators. Our behavior and decisions are based on a mixture of calculation, emotions, and internalized norms, with calculation often a minor component of the cocktail.

The first cities and states arose 5,000 years ago. One of these archaic states, the Old Kingdom of Egypt (2650–2150 BCE), the one that built the Great Pyramid of Giza, had a population of between one and two million, which is beginning to approach the social scale of the most complex social insects, ants and termites. The

In other words, the important statistic is the risk of violent death for each person. To illustrate this point, there were 49 homicides in Denmark in 2012 (population: 5.6 million), so the chance of any particular Dane being murdered that year was less than one in 100,000. But in a typical small-scale society, with a population of, say, 1,000, 49 homicides would translate into one chance in 20 of being murdered. As

Such perfection endures. For more than two millennia after horse-riding was invented, the warhorse remained the most important military technology bar none. A plentiful supply of horses was critical even in the 19th century, well after firearms had replaced the bows and arrows. Have you ever wondered why Napoleon, who won all of his battles until 1812, lost one battle after another in 1813 and 1814, leading to defeat and abdication? The surprising answer is: horses.

Humans are uniquely good throwers. No other species even comes close. Monkeys and apes can throw branches, rotten fruit, and excrement (I still remember an encounter with an irate troop of howler monkeys in Costa Rica . . .), but they do not use projectiles as lethal weapons in hunting or combat. Our closest relatives, chimpanzees, are quite pathetic at throwing.94 Imagine

Malthusian-Ricardian theory predicted that an increasing population would result in a specific progression of effects. Rents would rise first, with grain prices lagging behind rents, the price of industrial goods lagging behind grain prices, and workers' wages bringing up the rear. The evidence showed that this was precisely what happened (until the whole system was dramatically changed in the nineteenth century).

Mathematical theory tells us that when a dynamical system has two kinds of nonlinear feedback loop with different periods, these two mechanisms are likely to interact nonlinearly and may generate erratic, unpredictable-looking behavior known as mathematical chaos (Gleick 1987).

These four mechanisms, (1) competition between groups, (2) competition within groups, (3) cultural distance between competing groups, and (4) cultural homogeneity within groups are not the only processes that can affect the spread of cooperation norms.

science is not only about building carefully-constructed theories that explain general phenomena. It is also, and primarily, about distinguishing good explanations from bad ones. This is where traditional history has been deficient. Historians have created, and continue to create, new explanations, but they are not in the business of testing them with data.

During disintegrative trend reversals, these processes work in reverse. Abatement of elite overproduction decreases intraelite competition. Additionally, there is another curious dynamic that tends to increase intraelite homogeneity, the "closing of the patriciate", in which the established elites close their ranks to newcomers and dramatically reduce, or even reverse upward social mobility.

Gradually, human societies started extricating themselves from the worst forms of oppression. Human sacrifice and deified rulers went out of fashion. Slavery was outlawed, and privileges were taken away from nobles. Human societies regained much of the lost ground. We are still not as egalitarian as hunter-gatherers --there are the poor and the billionaires-- but we are much better off than we were during the days of god-kings.

External war often played an important role in increasing or sustaining cooperation among the elites, as well as cooperation between the elites, the state, and sometimes even commoners. During integrative phases, governments in collaboration with the elites often used external war to bring about periods of national consolidation. Additionally, successful wars of conquest yielded abundant rewards to be shared between the state and the elites.

As a result, periods of intense conflict tend to recur with a period of roughly two generations (40–60 years). These swings in the social mood may be termed "bi-generation cycles" because they involve alternating generations that are either prone to conflict, or not.

the dynamical pattern characterizing sociopolitical instability in historical societies (see, for example Figure 1.1) is more complex than just a sequence of secular integrative (relatively stable) and disintegrative (relatively unstable) phases. The jagged, "saw-toothed" nature of the trajectory suggests that there is another, shorter cycle superimposed on the longer multi-century oscillations.

Why was cultural group selection the key to the transition from forager to farmer? Because you cannot switch to farming when everybody else in your community is foraging. The whole group needs to shift together. It requires a new set of cultural norms and institutions shared by all. The most important such institution would have been property rights over the food that you have grown.157 The

Evidence is overwhelming that, after switching to agriculture, human stature decreased, a very reliable indicator of a decline in overall wellbeing. People fell sick more often because of higher population density and because pathogens jumped from domesticated animals to humans. The quality of nutrition declined, as is abundantly documented in ancient bones and teeth.

in a struggle between two groups of people, the group with stronger norms promoting cooperation and the most people following such norms has a greater chance of winning.

It is much easier for equals to achieve the unity of purpose and to develop a common course of action. Egalitarianism enables cooperation.

one of the most reliable predictors of state collapse and high political instability is elite overproduction (Turchin and Nefedov 2009:314).

In other words, theorists like van der Leeuw envision that a switch from hunting and gathering to agriculture creates a virtuous circle between problem-solving capacity and societal size, gradually leading to an increase of the scale of cooperation. I