Despite the obvious complexity of science, its deepest discoveries come from the simplest questions. The question Christine Kenneally explores in The First Word is so simple that for a long time scientists did not even consider it a legitimate question: How did we learn to speak?

That question has always fascinated the curious. As Kenneally tells it, a pharaoh once imprisoned two babies in a cave without human contact to see what sorts of things they would say, believing they would speak the “”original”” human language. (One of them eventually came out with something that sounded like the word for “”bread.””)

What interests Kenneally, however, is not what the first language was but how we even developed the ability to come up with languages. She begins her story in the 1950s, when the science of linguistics was completely in thrall to B. F. Skinner, the “”behavioral”” scientist who believed that all human activity was basically predictable. In the view of Skinner and his followers, humans were little more than very intricate machines.

This view was overthrown by the young MIT student Noam Chomsky, who virtually invented modern linguistics with his 1957 book “”Syntactic Structures.”” Chomsky laid the foundations of his argument on the simple fact that children learn to speak quickly – too quickly, given how incredibly difficult and subtle languages are.

Given that children enter the world knowing nothing at all, it is nothing less than mindboggling that within a few years they will not only learn thousands of words but grasp, in many ways unconsciously, how to put them together. Humans, Chomsky concluded, must be born with the innate ability to learn languages.

Chomsky’s great insight had such profound and far-reaching implications that he became the most famous linguist in the world, hailed as a new Einstein in some quarters and damned as a “”cult”” leader with “”evil side effects”” in others. But his discovery still didn’t answer a nagging question: How did humans learn to speak in the first place?

Kenneally’s search for the answer to that question reveals the vast gulf between what we think we know and what we actually know. Did the ability to speak evolve along with the rest of us? If so, could animals learn to use language, too?

That rather frightening question haunts Kenneally’s book, which relates stories of chimpanzees that could follow complex commands, a parrot with an enormous vocabulary, and a seal that barked coherent sentences in such a humanlike way that it could fool its keepers.

Humans once believed that it was the ability to make and use tools that set them apart from the “”lowly”” animals. That fond thought ended in 2001, when a researcher studying crows videotaped one of them bending a wire into a hook in order to grab food.

Kenneally often seems to be searching for a coherent way to tell this marvelously incoherent story. Still, her book is a superb introduction to a forbiddingly complex yet fiercely important subject.

– Justyn Dillingham