Was the ‘language gene’ FOXP2 key to human evolution?

In the vexing question of what defines humanity, language is a common answer. As thinkers like Noam Chomsky and Steven Pinker argue, humans have a unique, innate capacity to understand grammar and develop language. Evolutionary biologists have argued for years about whether language was key to our evolution, and new research on the FOXP2 gene argues that it wasn’t.

The FOXP2 gene is known as the ‘language gene’ and quickly became famous in 2002. Researchers identified a mutation in two amino acids around 200,000 years ago that was believed to be a selective sweep, meaning that it rapidly spread across all humans due to its selective advantage. The gene was believed to have enabled us to speak by improving vocal learning, as shown by its role in birds and mutations leading to problems with language. This ability to speak became a selective sweep as it’s a competitive advantage for coordinating during activities like hunts.

Evolutionary biologists have argued for years about whether language was key to our evolution, and new research on the FOXP2 gene argues that it wasn’t

However, more research into FOXP2 cast doubts over this conclusion. In 2008, it was revealed that Neandertals retained the same two amino acid mutations. This was important for two reasons; first, it meant it couldn’t have given humans specifically a selective advantage, and second it meant the mutations happened before the lineages of Neandertals and modern humans diverged, thought to be approximately 700,000 years ago. And in 2009, the same researchers that published the original research in 2002 didn’t lead to the evolutionary sweep. Despite this, other mutations in FOXP2 left the possibility open.

Elizabeth Atkinson led a new study to re-evaluate this hypothesis by taking advantage of improved genomics technology and resources. The team conducted a whole genome statistical analysis which included more people, particularly of African descent. Atkinson’s team discovered that the sweep didn’t appear when African genomes were separated from European/Asians. But what does this mean?

The team conducted a whole genome statistical analysis which included more people, particularly of African descent

When individuals migrated outside of Africa, they carried specific alleles of the FOXP2 genes and the remaining alleles remained in Africa. This phenomenon was observed in other regions of the genome that scored at similar levels to FOXP2, meaning that the gene itself didn’t have the selective advantage to cause a selective sweep. Instead, it was a result of a population growth that changed many parts of the genome including FOXP2.

Whilst it doesn’t mean FOXP2 isn’t important for language and its evolution, it challenges the way geneticists think about evolution and whether selective sweeps were common drivers in human reason. Another potential reason for this oversight is assuming FOXP2 is the one gene for developing language. In reality, a majority of human traits are the result of multiple genes and their interactions with each other.

Another potential reason for this oversight is assuming FOXP2 is the one gene for developing language

This was shown in another experiment where the gene was inserted into mice to analyse its impact and, disappointingly, the mice didn’t start speaking. Though it changed the squeak, it also changed neural circuitry to decrease exploratory behaviour showing us that something like language is far too complex to be explained by a single gene. As archaeogeneticist Johannes Krause reminds us, “it was not the one gene to rule them all.”