jamie writes: "It seems the Campbell's monkey has a vocabulary with at least six types of basic call, but they combine them and string them together to communicate new meanings. For example, the word for 'leopard' gets an '-oo' suffix to mean 'unseen predator.' But when that word is repeated after 'come over here,' the combination means 'Timber!' — a warning of falling trees. Scientists have known for some time that vervet monkeys have different warning calls for different predators — eagle, leopard and snake — but unlike the Campbell's monkeys, vervets didn't combine those calls to create new meanings, a key component of syntax. The researchers plan to play back recordings to the monkeys to test their theories for syntax errors."