"Todd: Of course, one can placate the people with bread and money, but only for a while. Revolutions usually erupt during phases of cultural growth and economic downturn. For me, as a demographer, the key variable is not the per capita gross domestic product but the literacy rate. The British historian Lawrence Stone pointed out this relationship in his study of the English revolution in the 16th and 17th centuries. He saw the critical threshold at 40 to 60 percent.
SPIEGEL: Well, most young Arabs can now read and write, but how is the birth rate actually developing? The population in Arab countries is extremely young, with half of its citizens younger than 25.
Todd: Yes, but that's because the previous generation had so many children. In the meantime, however, the birth rate is falling dramatically in some cases. It has fallen by half in the Arab world in just one generation, from 7.5 children per woman in 1975 to 3.5 in 2005. The birth rate among female university graduates is just below 2.1, the level needed to maintain a population. Tunisia now has a birth rate similar to that of France. In Morocco, Algeria, Libya and Egypt, it has dropped below the magic threshold of three children per woman. This means that young adults constitute the majority of the population and, unlike their fathers and mothers, they can read and write, and they also practice contraception. But they suffer from unemployment and social frustration. It isn't surprising that unrest was inevitable in this part of world.
SPIEGEL: Is that why angry young men are taking the revolution into the streets, while there is a lack of recognized older forward-looking thinkers and leaders?
Todd: That isn't surprising. Young men led the revolutions in England and France. Robespierre was only 31 in 1789, and he was 36 when he was sent to the guillotine. His adversary Danton and his ally Saint-Just were also young men, one in his early 30s and the other in his mid-20s. Although Lenin was older, the Bolshevik shock troops were made up of young men, as were the Nazi storm troopers. It was young men who faced off against the Soviet tanks in Budapest in 1956. The explanation is banal: Young men have more strength and more to gain."