Compositionality

In a new study published on Thursday in Science, researchers report that bonobo communication is rich in a feature that linguists call compositionality. 

This refers to the way we string words together to compose larger structures with more complicated meanings. 

Linguists divide compositionality into two categories, a simple version and a more sophisticated one, and researchers have long thought human language stands alone in the higher tier. 

Previous studies have found that some primates and birds are capable of “trivial” compositionality, in which words that each have a specific meaning on their own can be added together to create a fuller, more meaning-rich picture (“bake pie”).

But the new study shows that bonobos, like us, seem to do something a bit more advanced than that. 

In “nontrivial” compositionality, certain parts modify others. An example is the sentence “they baked a pumpkin pie.” Here “pumpkin” and “pie” join to form a new composite idea. 

This strategy gets more bang for your communicative buck, according to the new paper’s co-senior author Simon Townsend, who studies comparative communication at the University of Zurich. 

“That’s what we've evolved it for,” he says, “to add this important nuance and complexity to the meaning that we convey.”