Too much testosterone and "good, bad luck" may have helped create "Western Civilization." I suggest increases in testosterone separated hominids from other primates and directly participated in producing "human" characteristics, that is, human evolution. (This is identifiable today; human males and females produce more testosterone than chimpanzee males and females.) Notwithstanding testosterone's positive influence, testosterone's effects periodically produce negative consequences when levels become extraordinary in a population. Too much testosterone adversely affects the brain and immune system and civilizations.

For example, I think too much testosterone triggers early puberty, which interrupts final maturation of the frontal lobes of the brain. This part of the brain creates hypotheses: "What happens if I do this?" Reduced hypothetical thinking reduces the ability to "do" science and art and control impulses. As humans advanced with increasing testosterone, brains increased in size and function. Therefore, as humans began to migrate out of Africa, advancements in thinking and better impulse control (being civilized) formed civilizations in Northern Africa, the Mid East, then more distant places. Eventually, however, these civilizations experienced the adverse effects of too much testosterone. These civilizations emerged, produced significant accomplishments, then stagnated.

Civilizations evolve from groups of people living where conditions are good for reproduction; this is called "feed and breed." These groups eventually increase in testosterone because people of higher testosterone produce babies faster than those of lower testosterone. I suggest human migrations occurred because aggressive, high testosterone people push less aggressive, low testosterone people away from the group. Following periodic increases and declines in testosterone, groups pushed north and west from the Mid East eventually became "Europe." Europeans produced intellectual accomplishments, again, as occurred in the Mid East, until their testosterone increased excessively. When this happened, the "Dark Ages" occurred. The entire populations, on average, lost the abilities of the advanced frontal lobes. Europe became stagnant.

Fortuitously for Europe and the West, another, consequential, negative aspect of too much testosterone occurred, that is, increased vulnerability to infections. Therefore, populations of that time were at increased risk of infections. Where infectious agents gained entry into high testosterone populations, pandemics occurred. These epidemics of Europe accomplished something "beneficial," the epidemics removed most of the people of high testosterone. The surviving people of lower testosterone produced the intellectual accomplishments known as the "Renaissance." Since the epidemics did not occur in the "East," there was not a large removal of people of high testosterone; the Renaissance was limited to Europe. "Western civilization" is the result of the "good luck" of having epidemics remove the majority of people of high testosterone.