Humans have language and other animals don’t. That’s obvious, but how it happened is not. Since Darwin’s time, scientists have puzzled over the evolution of language. They can observe the present-day product: People today have the capacity for language, whether it be spoken, signed or written. And they can infer the starting state: The communication systems of other apes suggest abilities present in our shared ancestor.
But the million-dollar question is what happened in between. How did we transition from ape-like communication to full-fledged human language?
Most scientists think this happened in stages, as our ancestors evolved the adaptations needed for language. In earlier stages, human ancestors would have used a kind of protolanguage — more complex than ape communication, but lacking elements of modern language.
But what exactly was this protolanguage like? That’s where we hit considerable debate. Some researchers argue that our ancestors sang before they spoke. Others claim protolanguage was dominated by pantomimed gestures — a society built on charades.
Here, I’ll do my best to summarize prevailing models for language origins, drawing largely from a 2017 academic review by evolutionary biologist W. Tecumseh Fitch.
What Makes Language, Language
Before trying to explain how language evolved, we need to clarify exactly what evolved. We must define what language is and how it differs from the communication abilities of our closet evolutionary relatives, the great apes.
In human language, arbitrary sounds and signs represent specific words, which can be learned, invented and infinitely combined within grammatical structures. We can talk about anything we can think — plans, pancakes, politics — including what is not the case: “I have no plans to make pancakes or enter politics.” And many statements have specific meanings that are context dependent. For instance, “How are you?” can be a greeting, not a genuine inquiry. Language allows us to bond with others, or to deceive them. And although our native tongue is not innate, toddlers pick it up without conscious effort.
These qualities make language an extraordinary communication system found exclusively in humans. But the system can be dissected into components, or traits necessary for language. And these emerged at different times in our evolutionary past. Traits shared with other apes likely existed millions of years ago in our common ancestor. The traits we don’t see in other apes probably only emerged in hominins, the evolutionary branch that includes humans and our extinct relatives.
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