THE GRAMMAR GENE

By Vineeth Rajan

In 1998, a British family astonished academics around the world with the apparent reconciliation of linguistics and biology that they had brought about. The family, dubbed the KE family, had members that suffered from developmental verbal dyspraxia (DVD), showing severe problems with speech production.

DVD was the first speech disorder that exhibited Mendelian Inheritance or patterns in the family tree that indicated that the disorder was caused not by environmental factors like other linguistic disorders, but genetic factors. Many British institutions, like the Sanger institute and the University of Oxford funded and worked on the genomic analysis of this family.

The research showed that language production, at least in humans, was underpinned by genetics, which was a fascinating discovery of the time. Before this, language was considered to be something rather arcane and its mechanics, not fully explicable by biology or linguistics; there was not much evidence that explained language in humans scientifically. The study not only showed that language was biological in nature, but genomicists could also pinpoint the gene in which mutations occurred and caused the disorder: the FOXP2 gene. This was dubbed ‘the language gene’ or ‘the grammar gene’ and was immediately thought to be the genetic origin of human language.

Genes encode proteins that play roles in the characteristic or function associated with the gene; for example, this gene encodes a protein also called FOXP2, after which the gene was termed. It was found that fetal brains show high levels of expression of the FOXP2 gene, which means the gene is especially active in coding for and producing the FOXP2 protein in the brain. This showed that the disorder was neurological and not to do with muscular paralysis of speech organs, igniting intrigue in contemporary linguists. Here, genomics highlighted the heavy neurological element of linguistic capacity, showing that it was the work of the brain that facilitates human language.

However, academics soon realised that if FOXP2 underlies human language, we should find significant differences if not an absence of the gene in other organisms. What we do see is the presence of the gene in many vertebrates and, according to a 2005 study, ‘extreme conservation of FOXP2 sequences in birds’ and mammals. Although this shows that the gene is not ‘the language gene’ as was thought after the 1998 study, genomic data from the 2005 study suggested that FOXP2 plays a strong and evolutionarily conserved role in the brain of the vertebrates it is active in, having a similar ‘expression pattern in neural tissue’ ‘in birds and mammals’. It was also shown to be important in song-learning in birds and echolocation in bats through analysis of the gene mutation phenotypes or “symptoms”.  All this evidence showed that the gene, while not being specific to human language, was strongly associated with fine vocal control.

The FOXP2 gene was sequenced in 7 different species of birds, in which the sequences were identical to each other, showing strong inheritance of the gene. The study also states that song learning evolved three times among birds in parallel with each other, showing the significance of this gene in birds as a whole.

As to how the gene is evolutionarily conserved, meaning the gene showed unusually few changes across species, the study claimed that ‘population genetic studies of FOXP2 revealed a selective sweep in recent human history’, meaning that a mutation in this gene in humans was so beneficial that it spread across the entire population though natural selection. This strongly suggested to the researchers that this mutation was key to how human language evolved, underlying the complexity of human language that we do not see in other species. These mutations were shown to have nto occurred in any other species, explaining the uniquity of human language.

As pointed out to Mark Pagel in his TED talk on prehistoric language, the FOXP2 gene was shown to be present also in Neanderthals, which goes against the linguistic consensus that language played a significant role in overpowering of Homo sapiens over the Neanderthals. Pagel explains this through pointing out that the FOXP2 gene need not be completely deterministic of language and having the gene doesn’t necessarily implicate use of language. This is interesting, as it shows that, by this point, the popularity of the FOXP2 gene in the linguistic community had diminished, no longer being as important to language as it was seen to be before.

However, in 2008, genomic analysis supplanted the results of the many genomic studies done at the start of the 21st century and proved that no such ‘selective sweep’ occurred in recent human history. The recent analysis used a far more diverse and large sample than the twenty people used in the earlier research, explaining that the lack of diversity in the earlier samples distorted the results. Furthermore, hominids like the Neanderthals, who are widely regarded to have not used human language at all, show presence of the FOXP2 gene. Adherence to the idea of this gene as being the source of human language would go against the general consensus in multiple academic communities.

This is a prime example of science collecting and assessing evidence and reforming its hypotheses accordingly. Often, scientific theories, though very exciting, can be refuted and ruled over by new evidence. The outcome of decades of genomic research into the source of human language has not been futile however, because it shows that complex genetic factors that are actually behind human language, perhaps making this human ability that much more intriguing.

References:

Nudel, R., & Newbury, D. F. (2013). FOXP2. Wiley interdisciplinary reviews. Cognitive science, 4(5), 547–560. https://doi.org/10.1002/wcs.1247

D. M. Webb, J. Zhang, FoxP2 in Song-Learning Birds and Vocal-Learning Mammals, Journal of Heredity, Volume 96, Issue 3, May/June 2005, Pages 212–216, https://doi.org/10.1093/jhered/esi025

The Scientist Magazine®. 2020. Language Gene Dethroned. [online] Available at: <https://www.the-scientist.com/news-opinion/language-gene-dethroned-64608> [Accessed 1 April 2020].

Pagel, M., 2020. How Language Transformed Humanity. [online] Ted.com. Available at: <https://www.ted.com/talks/mark_pagel_how_language_transformed_humanity> [Accessed 15 May 2020].