Heinsohn demonstrated that when 30 percent or more of a population is aged 15-29, you have too many young men with bad attitudes, and the result is a jump in crime, terrorism and civil unrest. Heinsohn showed that in 90 percent of the 67 of the countries that have the 30 percent “Youth Bulge” (as demographers put it) you have massive unrest. Moreover, 13 of the 27 nations with the largest Youth Bulge are Moslem. In fact, most of the Youth Bulge is found in Africa and in Moslem nations.

Heinsohn also points that many historical upheavals were attributable, at least in part, to the Youth Bulge. These would include the American and French Revolutions and many other uprisings in places like Ireland and Latin America. The current growth of Youth Bulge can largely be blamed on Western efforts to improve the lives and health of people in the developing world. No good deed goes unpunished.

This “youthquake” problem is taken for granted by many experienced terrorism and criminology experts. But the pattern is not generally recognized as the main cause of unrest. However, historically it appears to be the case. In pre-industrial societies, 5-10 years of favorable weather would create an abundance of food, and a population explosion. There would follow a period of civil unrest and wars as these kids came of age. Zoologists note the same pattern in animal populations. Humans are more complex beasts, but just as the American crime rates began to plunge in the 1990s, as the Youth Bulge disappeared, so will the civil disorders and terrorism now causing so much misery.

I guess that’s good news, in a way, though it’s certainly ominous with regard to countries that are stable now but that face an excess of young males, like China and India.