One of the animals generated recursive sequences in around half of the trials. Three- to four-year-old children, by comparison, formed recursive sequences in approximately 40 percent of the trials.

This result suggests that the ability to identify recursive sequences, often considered a defining feature of language, may have initially evolved for other purposes.

A multi-institutional research team found the cognitive ability to represent recursive sequences occurs in humans and non-human primates across age, education, culture and species.

A contested study suggests the ability to embed sequences within other sequences, a skill called recursion and crucial to grammar, has ancient roots.