Here are the best stories in science this week ⁠ ⁠ Hearing a sound while working on a complex puzzle, and then hearing it again during sleep, helped lucid dreamers better tackle the problem the next day. Humans are the only primates with a chin – now we finally know why. Biologists have debated the reason why Homo sapiens evolved a prominent lower jaw, but this unique feature may actually be a by-product of other traits shaped by natural selection ⁠ Babies in the West commonly lack a gut microbe