Illustration by Thomas Porostocky
Language is an innate faculty, rather than a learned behavior. This idea was the primary insight of the Chomskyan revolution that helped found the field of modern linguistics in the late 1950s, and its implications are both simple and profound. If innate, language must be genetic. It is hardwired within us from conception and evolved from structures and genes with analogues existing throughout the animal kingdom. In a sense, language is universal. Yet we humans are the only species with the ability for what may rightly be called language and, moreover, we have specific linguistic behaviors that seem to have appeared only within the past 200,000 years—an eye-blink of evolution.
Why are humans the only species to have suddenly hit upon the remarkable possibilities of language? If speech is a product of our DNA, then surely other species also have some of the same genes required for language because of our basic, shared biochemistry. One of our closest relatives should have developed something that is akin to language, or another species should have happened upon its attendant advantages through parallel evolution.
A quasi-paradox has persisted within the field of linguistics, because the sudden emergence of such a complex, limitless system in a single species is hard to rationalize in terms of standard evolution. Its rapid spread makes language seem more like a viral epidemic that swept through the human population rather than a trait inherited through the typical dynamics of evolution.
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Luckily, two recent advances have made it possible to rigorously address the problem of language's evolution for the first time. Molecular biology (including the publication of the human genome) and the so-called evo-devo paradigm now permit us to establish new and often quite unexpected connections among very different species. In addition, linguists' understanding of syntax—how words are strung together into grammatical sentences—has developed to the point where language can be broken down into its basic procedural components. These components can now be seen to resemble traits observed in other species—with functions that appear to be completely unrelated to familiar thought processes. Language may indeed be unique to humans, but the processes that underlie it are not.
What we are beginning to see is that a set of disparate cognitive traits lends credence to the fact that language is genetic, and arose suddenly. Knot-tying, dancing, and typing, for instance, are all part of the unique equation that gave rise to language. But the genetic underpinnings of speech, and the machinations of its evolution, are best found in its analogues in the nonspeaking animal kingdom. Our closest relative, the chimp, would be the most natural species to look to first, but it can teach us only part of what we need to know. There seems to be a better set of species that can tell us the complete story of human language's evolution: songbirds.
To appreciate why songbirds such as finches, which diverged from mammals over 300 million years ago, will help to elucidate the nature of language, we must first look at the story that brought genetics and language together. In the 1990s, a family was discovered in London with a certain impairment that appeared to be specific to language. Afflicted members had no discernible decrease in intelligence, but there was definitely something askew with their ability to speak. Genetic studies on the family lead to the discovery of a single affected gene responsible for the impairment, referred to as FOXP2, which was soon popularly baptized "the language gene."