Widely considered as the hardest problem in science, the origins of human language have been searched for by researchers for thousands of years. Yet, in spite of relentless efforts, the beginnings of language remain a mystery. The difficulties with this inquiry stem from the lack of direct evidence. Researchers can only draw inferences from fossil records, archaeological evidence, contemporary languages, language acquisition research, and comparative studies of human language systems. From these inferences, theories have been developed that try to make sense of why, when, how, and where humans started to communicate linguistically.

The many theories that have been proposed can be generally categorised by their underlying assumptions as either continuity theories or discontinuity theories. Continuity theorists hold the belief that because language is so complex, it must have evolved from earlier pre-linguistic systems of communication among primate ancestors. Thus, language would have appeared gradually over time. Discontinuity theories, on the other hand, are based on the opposite idea. They hold that language is a unique trait that is incomparable to anything found among non-humans, and thus must have appeared suddenly during the course of human evolution. Further distinction could be made between theories that claim language is an innate ability and those that suggest language is socially constructed. But the continuity versus discontinuity categories provide a much clearer overview of the different schools of thought.

The vast majority of scholars support continuity theories. The earliest of these were what we broadly refer to as vocal theories, which suggest that the changes around 100,000 years ago in the mouth and the pharynx, in addition to increased brain volume, gave humans voluntary control over vocalisation. But there are many variations of vocal theories. For example, one theory suggests that language originates from primates imitating natural sounds, and then using those imitations to refer to the things associated with the relevant sound. Other vocal theories attribute language development to involuntary sounds such as shouts of joy, cries of pain, and laughter. However, vocal theories have been widely discredited as naive by modern scholarship.

Another school of thought supports gestural theories, which suggest that the physical evolution of the human body lent itself to the use of sign language and then later vocal language. The generally agreed-upon assumption is that the transition to walking on two legs versus four freed the upper limbs to participate in gestural communications. Then, eventually, vocal language developed as a way to further free up the arms and hands for other uses. In other words, vocal language was the “cheapest” form of communication, requiring the least expenditure and allowing the limbs to be used for important activities such a gathering food, mobility, self-defense, and other such essential needs. Proponents of gestural theories estimate that the gradual transition to spoken languages was completed about 50,000 years ago.

There are also social origin theories that point to the usefulness of language in more complex social worlds as the causative factor in its emergence. Robin Dunbar’s gossip theory is the most well known from this school of thought. From his perspective, the majority of conversations are gossip; in other words, people gather news and information about other people. Rather than seeing such exchanges as pettiness, Dunbar argues that gossip provides information vital to establishing trust and distinguishing allies from enemies. In larger, more complex societies, this is an essential survival mechanism. Thus, he argues that this exchange of information about one’s social environment is the primary function of language. This theory is favored by sociolinguists who see the development of language as rooted in the political nature of humans and their inherent need to form alliances and exclusive groups.

In comparison to the large number of continuity theories, there are relatively few ideas about the origins of human language identified as discontinuity theories. Perhaps the most widely held belief is in a divine source. Several religions and spiritual sects around the world see language as originating from deity, such as a god or Sun spirit. Most traditions that hold this belief have tales built into their oral or written histories that explain how language was transmitted from the divine to the human.

However, not all discontinuity theories have religious roots. In recent years, genetic theories, otherwise known as innateness theories, have gained in popularity. Noam Chomsky, a major proponent of a discontinuity theory, argues that the capacity for language is genetically hardwired in human offspring and not in other animals. He posits that a single chance mutation occurred in one individual around 100,000 years ago, instantaneously producing language faculty in near-perfect or perfect form. Chomsky further argues that there is evidence of a universal grammar being hardwired in the brain, and which precedes language variants. While many scholars are highly critical of Chomsky’s ideas, mounting evidence of the interrelatedness of all languages lends support to his claims.