Why apes can’t talk

The fossil record can also provide insight. Speech itself clearly does not fossilise, so researchers have searched for proxy evidence in the skeletal remains of extinct human relatives. For example, some researchers have argued that the position and shape of the hyoid bone (the only bone in the vocal tract) can tell us something about the origins of speech.

Similarly, other have argued that the diameter of the thoracic canal (which connects the thorax to the nervous system), or the hypoglossal canal (through which the nerves travel to the tongue), can tell us something about breathing, or speech production. And the size and shape of the tiny bones in the middle ear may be able tell us something about speech perception. But, in general, the fossil record is simply too limited to draw any strong conclusions.

Finally, comparing genetics of humans and other species has provided insight into the origins of speech. One much-discussed gene, that seems to be relevant for speech, is the FOXP2 gene. If this gene mutates it leads to difficulties with learning and producing complex mouth movements, and wide-ranging linguistic dificiencies.

It was long thought that the DNA sequence changes in the human FOXP2 gene were a unique trait, related to our unique ability to use speech. But more recent studies have shown that these mutations are also present in some extinct human relatives, and the changes in this gene (and, perhaps language itself) may be much more ancient than previously thought.

Technological developments, such as further ancient DNA sequencing of extinct species, and increased knowledge of the neurobiology of language, are certain to provide further giant leaps. But the future of this contentious and complex field will likely depend on large-scale, multi-disciplinary collaboration. Comparative studies like ours, comparing traits across a range of species, was the primary tool used by Darwin. No doubt such studies will continue to provide important insights into the evolution of this incredible aspect of our behaviour.

Jacob Dunn is Senior Lecturer in Zoology, Anglia Ruskin University