Humans are the only species, that we know of, that has been capable of verbal language, until perhaps now. Okay, just so we know, I’m setting the bar pretty high so that Dolphins don’t make the cut, but maybe our closest extinct relative could have made it over that bar. Yes, maybe Neanderthals had language.
While CNN and other regular news agencies are all having a blast talking about Neanderthals with red hair, sciencedaily.com reports that scientists at the Max Planck Institute for Evolutionary Anthropology have been doing some very interesting research on a gene called FOXP2, which is involved in language. Humans with sub-functional copies of this gene lack speech abilities, and humans and chimps differ in two key parts of the sequence - evidence of adaptive change that may have contributed to our ability to have language. Well now, it seems, the Neanderthals, who shared a common ancestor with us about 300,000-400,000 years ago, also have the human version of those adaptive changes.

A new study in Current Biology reveals that adaptive changes in a human gene involved in speech and language were shared by our closest extinct relatives, the Neandertals. The finding reveals that the human form of the gene arose much earlier than scientists had estimated previously. It also raises the possibility that Neandertals possessed some of the prerequisites for language.

The gene, which is called FOXP2, is the only one known to date to play a role in speech and language, according to the researchers. People who carry an abnormal copy of the FOXP2 gene have speech and language problems.

“From the point of view of this gene, there is no reason to think that Neandertals would not have had the ability for language,” said Johannes Krause of the Max Planck Institute for Evolutionary Anthropology. He noted, however, that many as-yet-unknown genes might underlie the capacity for language. Once found, those would have to be examined in Neandertals as well.

Previous analyses indicated that a very recent rise in the human FOXP2 variant had occurred as a result of strong selection, less than 200,000 years ago, added Svante Pääbo, also of the Max Planck Institute. “Because we know that Neandertal and modern human populations diverged more than 300,000 years ago, we would have guessed that these changes in FOXP2 would have happened after we separated from Neandertals,” Pääbo said, noting that the human version of FOXP2 differs from that of chimps in two places.

Here’s the abstract from the paper:

Although many animals communicate vocally, no extant creature rivals modern humans in language ability. Therefore, knowing when and under what evolutionary pressures our capacity for language evolved is of great interest. Here, we find that our closest extinct relatives, the Neandertals, share with modern humans two evolutionary changes in FOXP2, a gene that has been implicated in the development of speech and language. We furthermore find that in Neandertals, these changes lie on the common modern human haplotype, which previously was shown to have been subject to a selective sweep. These results suggest that these genetic changes and the selective sweep predate the common ancestor (which existed about 300,000-400,000 years ago) of modern human and Neandertal populations. This is in contrast to more recent age estimates of the selective sweep based on extant human diversity data. Thus, these results illustrate the usefulness of retrieving direct genetic information from ancient remains for understanding recent human evolution.

A few caveats before we continue:

  • The Neanderthal gene is not necessarily identical to the human version. There could be other differences. But what they did, since there was so few DNA to work with, was test whether or not the ‘thals had the human version of the gene at the two positions where humans and chimpanzees differ. It would be very unlikely to find any other differences, but they could be there and this paper did not eliminate that possibility.
  • FOXP2, although it is called “The Language Gene” is probably not the only gene that is involved in the difference in linguistic abilities between humans and chimps. It’s the only one we know about. So therefore,
  • The paper did not conclude that Neanderthals could speak - but since the ‘thals had the human version of the only gene known to be involved in language, rather than the chimpanzee version, it suggests that they might have been able to. To put it another way, they probably could, and there’s no evidence, so far, that they couldn’t.
  • This research is still awesome.

The human diversity data that exists suggested a selective sweep - an evolution of the genetic code in our population, about 260,000-200,000 years ago, lasting for 50,000-80,000 years. This sweep included FOXP2. But if the Neanderthals have the same version of FOXP2 as modern humans, and we split from each other between 300k-400k years ago, how did we each get the same copy?

The authors split it up into three possibilities. (I think there are four.)

  1. Gene flow - the pro-language version originated after the Human-Neanderthal split, and passed from humans to ‘thals (or vice-versa) through interbreeding. (uh oh!)
  2. Earlier origin and sweep - the pro-language version of FOXP2 originated before the Human-Neanderthal split AND was advantageous for survival (used for language). This means that the selection sweep of many genes may have occurred earlier.
  3. Earlier origin not sweep - the pro-language version of FOXP2 originated before the Human-Neanderthal split but was not selected for strongly. Then, it became involved in language in the human line and was strongly selected for, while it was merely present in the Neanderthal line.
  4. (mine) Evolution is more complex than simple hypotheses often are….and if you want to play pseudoscientist on this one:
  5. Some nameless or named, natural or supernatural, disembodied or not, Designer (or designer, designers) put the pro-language version of FOXP2 in both Humans and Neanderthals. Just for kicks. Maybe to hear the Neanderthals’ cries not to be wiped off the face of the Earth. And we predicted it first! With our testable model, sho’nuff.

The authors dismissed that Humans and Neanderthals cross-bred. Most researchers in the field doubt that it occurred, I also doubt it. However, it is still a tantalizing hypothesis that may come into play in the coming years. They noted that studies of mitochondrial and Y-chromosome DNA are not common enough between the two species (again, using modern humans, not humans that lived at the time) to suggest cross-breeding. Wasn’t there a paper last year on anatomical features that suggested that the two species interbred? How about a gene that could have scooted over from one species to the other through breeding? Maybe they didn’t just co-habit.

I would also like to add that these are the parts of our genome that don’t recombine very much at all. So using them as a standard for whether or not genes flowed through interbreeding isn’t the best, but it’s what we’ve got.
The authors are right, however, to say that there isn’t enough evidence to conclude that there was introgression of this one gene between the species, all by itself. But when the Neanderthal genome is sequenced, that will be a much more interesting topic.

The second hypothesis, (third on their list, I thought it made more sense to list them this way) which is the one they accept, seems to be the more parsimonious. As in, an earlier origin for the modern version of the gene neatly explains its presence in both populations, and would suggest usefulness.

The third hypothesis, suggesting that the modern allele was in the common ancestor but not positively selected for by natural selection, is tenuous. Why, in absence of selection, would it get high enough in frequency to be present in Neanderthal DNA at a high enough frequency for us to pick it up, and only it up?

The fourth hypothesis should always accompany studies like this, IMO. Perhaps it introgressed with a few genes, and not huge chunks of DNA. Perhaps it was part of an earlier selective sweep, and the previously dated sweep at 260k years ago is still correct, just not for this gene? Perhaps like some genes in the Stickleback fish, it was present in the common ancestor, and wasn’t selected for until a later date, simultaneously in both species? Could environmental conditions have triggered a use for the rudimentary speech abilities in both hominids at the same time?

We’re bound to run into problems when we oversimplify. There’s no need to complicate things at this point, but as more evidence comes in, there may be a need to revise conclusions about the evolution of speech. And maybe add a few monosyllabic grunts to the new Neanderthal documentaries?
I simply cannot wait for the draft sequence of the Neanderthal Genome! It could be a year or so until it comes out, and when it does it’ll be better than the chimp genome. There are so many amazing discoveries waiting around the corner, that if you answered #5 for the explanation above, I’m speechless.

Oh, not every news source passed it over. Nicholas Wade, who’s work I quite enjoy, wrote a NY Times article about it.