How did language begin?

The question

Every human group ever studied has a fully developed language, spoken or signed, and almost every child learns one without being taught. No animal communication system known to science is comparably open-ended: human languages combine a limited set of sounds or signs into an unlimited number of new meanings. How, when and why did this ability appear in our lineage?

The question once seemed so hopelessly speculative that the Linguistic Society of Paris banned papers on it in 1866. It returned to science in the late twentieth century, drawing on linguistics, genetics, archaeology, animal cognition and computer modelling.

What we know

• Language leaves no fossils, and writing is only about five thousand years old, so all evidence about its origin is indirect.
• Homo sapiens appeared in Africa roughly 300,000 years ago. All living populations have languages of comparable complexity, and they began to separate more than 100,000 years ago, so the capacity for language was very likely in place before then.
• The gene FOXP2 is involved in speech: members of a British family with a damaged copy struggle with the fine movements of speaking and with some grammar. Neanderthals carried our version of the gene. But FOXP2 is not “the language gene”: it is one of many, and an early claim of recent strong selection on it in humans was not confirmed.
• Children can create language. Deaf children brought together in new schools in Nicaragua in the 1970s and 1980s developed a new sign language, which became more systematic with each new group of young learners.
• In laboratory experiments, an artificial “language” passed from learner to learner becomes more structured and easier to learn, though nobody intends it.
• Other animals have parts of the toolkit: songbirds learn their songs, apes can learn hundreds of symbols, some monkeys combine calls. None is known to build an open-ended hierarchical system.

Main hypotheses

A single recent change

Noam Chomsky and colleagues argue that the core of language is a computational operation that combines elements into nested structures, and that it may have appeared relatively suddenly in our species. Much of the rest, such as vocal learning, is older and shared with other animals.

Gradual natural selection

Steven Pinker and Paul Bloom argued that language is a complex adaptation for communication, built step by step by natural selection, like the eye, with each step giving its users an advantage.

Gesture first

Language may have begun with gestures and pantomime, with speech taking over later. Ape gestures are far more flexible than ape calls, and new sign languages arise easily.

Culture does most of the work

Perhaps biology supplied only general abilities — shared attention, imitation, a drive to communicate — and the structure of language emerged through cultural evolution, as languages adapted to be learnable by human brains.

Deep antiquity

Dan Dediu and Stephen Levinson argued that the capacity for language is much older, and was shared with Neanderthals and our common ancestor more than half a million years ago.

What would settle it

No single discovery is likely to. Progress would come from:

• Linking specific genetic changes to the brain circuits used for language, and dating them with ancient DNA, including from Neanderthals and Denisovans.
• Knowing how language is implemented in the brain, and so what exactly evolution had to produce.
• Comparative studies of which components other species have, and experiments showing which can emerge from cultural transmission alone.
• Archaeological finds that pin down when complex symbolic behaviour began.