Joe Biden lands in Saudi Arabia this morning, having spent two unremarkable days in Israel and the West Bank. As president, he has been unusually disengaged from the Middle East, and will probably return home with little to show for his peregrinations. We survey the state of sex education in Latin American schools, and explain why dinosaurs outcompeted other species.For full access to print, digital and audio editions of The Economist, subscribe here www.economist.com/intelligenceoffer
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