Genes and how they work may be the hottest dispute in biology right now, and since most other questions in biology cannot be settled until the gene question is resolved, everybody is marking time just now. I'm reminded of this point by a paper just published in the online journal¸ Biolinguistics. The paper ("[Eric] Lenneberg's Views on Language Development and Evolution and Their Relevance for Modern Biolinguistics") is by Cedric Boeckx and Victor M. Longa, both are linguists making a biological argument.
Eric Lenneberg was a lasting influence on this blog. I read his book in the early 1970s and ever since then have taken for granted that language has a biological and evolutionary history. This blog has staked its reputation on an evolutionary approach and I owe that confidence to Lenneberg. However, I confess that while I still have my copy of his book close to hand, I haven't read it in decades. It's nice to return to it. The book is, as the authors say, "a body of work of the highest interdisciplinary quality" [p. 254]
A basic question of biology has long been how a new generation acquires its traits. There are two basic answers:
Preformation – the next generation already exists in potential form. In the eighteenth century naturalists spoke of a homunculus, or tiny being that lived in the seed of the present generation. That idea proved wrong, but it exists in a more modern form, information controlling the formation of an individual is passed through the generations. Differences in individuals arise from changes to the information.
Development – a series of developmental interactions between genes, environment, and the rest of the organism's body. Differences in individuals arise from differences in interactions.
For the past half-century and more the preformation explanation has dominated. Genes are viewed as causative agents, the major element selected in evolutionary processes. Thus, if modern humans and Neanderthals share a gene, they share the trait as well. This point is especially important in the FOXP2 gene, associated with language. If the form of the gene supports language in us, it supported it in Neanderthals as well—or so the preformative theory insists.
The authors add, "that Generative Grammar has traditionally embraced the preformationist perspective by means of its defense of the need for a genetic program for language" . The Universal Grammar is assumed to be built into the brain whose modules are determined genetically.
More recently the emphasis has shifted. There is ample talk about Evo-Devo and epigenetics, but, suggest the authors, language scholars have not paused to absorb the full implications of the change. Genes, of course, still matter, but they are only one part of an interactive process. An abnormal gene, for example, may result in an abnormal organism, but it does not follow that the normal version of the gene causes the normal form of the organism. Similarly, breaking a wire in an automobile engine may mean the car won't move, but that doesn't mean the wire is what causes the car to move. This analogy has obvious implications for the FOXP2 gene, which was discovered in an abnormal form in a family with abnormal language difficulties. We cannot argue from that connection that the normal form of the gene causes normal language.
So if genes are not the causative agents shaping the organisms, what are they? They are part of the story, contributing to the probability of the organism attaining a particular state. We've already seen that the genetics of a population can determine the probability that the population speaks a tonal language, so the idea of genes shaping probabilities rather than serving as causes is not new to this blog. (See: Was the First Language Tonal?)
What does this tell us about the evolution of language? The authors don't say, but they seem to imply that the process is statistical and the result is statistical. Developments depend on interactions and it is quite arbitrary to pick one part of the interaction (such as the gene) and to say it is the key.
It is well known, for example, that children who are raised without human contact (there are a few wretched cases) do not develop language. Traditionally we say that this is an environmental effect that overcomes the genetic process. But if you think more broadly, it might be that human interaction doesn't just permit the genes to do their work. They might contribute to the development of language. In that case, there should be many examples of children acquiring language at different paces, depending on their interactions with speakers. It sounds doubtful, although every nursery school teacher knows that their children show a great range in language abilities. Identifying the sources of all this variety is plainly an impossibility and is unlikely to be attempted.
The paper's authors write that "innate traits are due to … any factor influencing development. Genetic factors are just one of them, but in no sense can they be regarded as the main or unique factors" . Yet the difficulty of identifying all the other factors leads me to suspect that for a long time to come the focus is going to remain on genes.