German researchers have discovered Neandertals apparently had the human variant of a gene that is linked to speech and language. A team of scientists, primarily from the Max Planck Institute for Evolutionary Anthropology in Leipzig, made the discovery during efforts to reconstruct a full genome of the extinct hominid.
The findings push back the estimated timing of the FOXP2 gene's selective sweep (rapid spread of a gene mutation due to the survival advantage it conferred) from 200,000 to 350,000 years ago, when the common ancestor of Neandertals and humans roamed the earth.
"From the point of this gene, there is no reason to think that Neandertals did not have language as we do," says Planck Institute geneticist Johannes Krause, a co-author of the study published in Current Biology. "However, many other as yet unknown genes are involved in language, so in the future these will have to be found and looked at in Neandertals."
The human version of the FOXP2 (short for fork-head box P2) differs from that of the chimp (the closest living relative of humans) in two places along the genetic code, causing differences in two amino acids in the protein coded by the gene. FOXP2 was first tied to language in 2001, when a mutation in it was shown to affect a person's ability to speak.
To determine which version of FOXP2 Neandertals carried, the research team extracted DNA from a well-preserved fossil found in the El Sidrón Cave in northern Spain. This marks the first time a particular gene was sequenced from a Neandertal's nuclear DNA. Although DNA taken from the cellular mitochondria (energy centers) is typically easier to access, fossils are often contaminated by human contact.
The team took steps to ensure they were sequencing Neandertal DNA and not modern human residues. Among them: sequencing specific parts of the Y chromosome and comparing them with those of modern human DNA. The samples were distinct, indicating that they were dealing with an authentic specimen.
When the sequencing was complete, the Neandertal FOXP2 showed the same two mutations that the human gene carries (compared with the chimp version). The group did not find any genetic evidence of interbreeding between humans and Neandertals, leading them to conclude this incarnation of the gene must have propagated and spread prior to the genetic split of the two hominid species more than 300,000 years ago.
Simon Fisher, a molecular neuroscientist at the University of Oxford in England, says the new work shows a better method for dating the evolution of certain genes, as opposed to inferring from changes throughout human evolution. He was more cautious about its link to Neandertal's speaking ability. "We do not think of FOXP2 as 'the speech gene,'" he says. "It is instead just one piece of a complicated puzzle, which likely involves many different factors. The FOXP2 gene has been around for a very long time, found in similar form in distantly related vertebrate species, and it may be important not only for brain development and function but also in other tissues."
Krause says the Planck team will continue to cobble together the Neandertal genome and chart the evolution of other genes by comparing Homo sapiens with Neandertal DNA. Some other candidates include ASPM, which is tied to microcephaly (a condition when the head is disproportionately smaller than the body), and MC1R, implicated in skin pigmentation.