Haiti's gang crisis takes a dark turn, plus the mother of all languages

Beset by years of gang violence, the Haitian government has enlisted the assistance of the ex-CEO of the defunct private military firm Blackwater, notorious for its role in the death of civilians in Iraq. Plus, the science journalist Laura Spinney traces the ancient origins of English, Russian, Hindi, Greek and more - back to a linguistic origin known as "PIE" (Proto-Indo-European).