Human beings are the only animals that cook, and the habit has left marks on the body. Coo breaks do starch a protein out the bo, so f less wo is le for t gut t do. Compared with other primates of similar size, humans have a strikingly short digestive tract and unusually small teeth and jaw muscles. The energy saved appears to have gone elsewhere: our brains consume about a fifth of the body's fuel at rest, a proportion no other primate comes close to.

Type only the missing letters. Each box is one letter, and the number of boxes matches the letters that are missing.