In groundbreaking work from the University of Warwick, researchers have found that wild orangutans vocalise with a layered complexity previously thought to be unique to human communication, suggesting a much older evolutionary origin. Consider the phrase – ‘This is the dog that chased the cat that killed the rat that ate the cheese’. It is a simple sentence comprised of repeated verb noun phrases - ‘chased the cat’, ‘ate the cheese’ - and is an example of layered complexity called recursion. Recursion is the repetition of language elements in an embedded way so that they form a comprehensible thought/phrase. Like Russian nesting dolls, the power of recursion mean we can combine a finite set of elements to deliver an infinite
