Scientists have not stopped wonderinghow and when human beings begin to be able to speak. Well, a recent analysis of our DNA has revealed a number ofevolutionary changes that were key to modifying the shape of our faces and larynxand what should have turned outdecisive to create the conditions that allowed the appearance of complex speech.
These alterations were not due to large massive mutations in our gene bundle. Rather,a series of small changes occurred in the activity of genes that already existed and that we shared with our immediate ancestors, the hominids.
These changes in the activity and expression of genes appear to be due to the fact thatour faces have become flatter compared to the more prominent jaws of the apes and hominids that preceded us. Genetic alterations tooresculpted the larynxand made it move further into the throat, which allowed those early humans to producemore complex, varied and subtle sounds.
The study, carried out by Liran Carmel and his colleagues from the Hebrew University of Jerusalem, offers an unprecedented look at the alterations and evolutions that our faces and vocal tract suffered at the genetic level and thatpaved the way for developing the sophisticated spoken language that we take for granted today. However, for another stream of anthropologists,as important or more important than genetic variations were changes in the brain. And it is possible that some of our most primitive ancestors could in some way speak, but in a more rude way, until those facial physical changes allowed to qualitatively improve the characteristics of human speech.
Liran Carmel, who is a geneticist, evolutionary biologist, and bioinformatician, and his team at the Hebrew University of Jerusalem analyzed DNA from people from two current populations and from four humans who lived about 50,000 years ago . They also studied some extinct humans, specifically two Neanderthals and a Denisovan , and genetic material from six chimpanzees and data from a database of people alive today. They focused on those genes that became more or less active throughout evolution. They looked at whether the genes had associated methyl groups to identify epigenetic changes. And it is that normally the methylated genes tend to become inactive while the unmethylated ones are activated, so changes in the methylation patterns are an indicator to track genetic activity and its alterations.
Image: “Changing the face. Our face and oral tract changed throughout evolution, giving us the ability to form complex language.” In pink, the tongue; in yellow, the hyoid bone; in orange, the epiglottis and in green, the vocal cords.
In modern humans there were drastic alterations in the activity of genes associated with the shape of the face and the structure of the larynx , compared to our ancestors. Specifically, the genes linked to the vocal cords and the development of the larynx were the ones that had changed the most in relation to the ancient hominids and primates. For example, the NFIX gene is much less active in humans. This gene is involved in the protrusion of the jaw and the development of the larynx, which suggests that it has been decisive for the human face to flatten and allow us to obtain the optimal facial configuration for speech , since the horizontal and vertical components of the vocal tract have the same length, as seen in the diagram.
References and Image:
Gokhman, D. ‘Recent Regulatory Changes Shaped Human Facial and Vocal Anatomy’. (2017). Doi: https://doi.org/10.1101/106955
