Islamist extremism: Green glass ceilings WHY pious and peaceable Muslims turn to ultraconservative and even violent versions of the faith is a subject of great interest for scholars and policymakers. But so far little effort has gone on studying the radicalisation of the clergy. Now Rich Nielsen of Harvard University has examined the books, fatwas (religious rulings) and biographies of 91 modern Salafi clerics, as well as of 379 of their students and teachers. He found that the main factors behind radicalism are not poverty or the ideology of their teachers (as might be assumed) but the poor quality of their academic and educational networks. Such contacts determined the clerics" ability to get a good job as imam or teacher in state institutions. In Saudi Arabia and Egypt, where most of the 91 came from, the government has long co-opted religious institutions. Those who failed to land a job were more likely to avow violence as a tool for political change. The figures are startling. Clerics with the best academic connections had a 2-3% chance of becoming jihadist. This rose to 50% for the badly networked. Mr Nielsen reckons he has proved causation by controlling for other factors - eliminating the chance that those more inclined to extremism shun state jobs, for example. "It's about a glass ceiling," he says. Clerics who don't get positions must compete to appeal to an audience. Jihadist views are a way of making themselves appear credible, since there is often a high cost associated with it, such as prison time. His research may help those seeking to stem the rise of radical preachers. Rather than spending a fortune snooping on them and then jailing them, it would be cheaper to offer them a decent job.