Researchers taping calls of the putty-nosed monkey in the forests of Nigeria may have come a small step closer to understanding the origins of human language.

The researchers have heard the monkeys string two alarm calls into a combined sound with a different meaning, as if forming a word, Kate Arnold and Klaus Zuberbühler report in the current issue of Nature.

Monkeys are known to have specific alarm calls for different predators. Vervet monkeys have one call for eagles, another for snakes and a third for leopards. But this seems a far cry from language because the vervets do not combine the calls into anything resembling words or sentences.

The putty-nosed monkeys have a "pyow" call meaning there are leopards about and a hacklike sound to warn of the crowned eagle. The "pyow" calls attention to a leopard on the ground.