THE UNPREDICTABLE SPECIES

Lieberman (Emeritus Linguistics/Brown Univ.; Toward an Evolutionary Biology of Language, 2006, etc.) examines the unique creative potential of the human brain.

While fully supporting natural selection, the author argues against a narrow approach that overemphasizes genetic determination, a shortcoming that he attributes to evolutionary psychologists such as Steven Pinker and Richard Dawkins. Lieberman seeks to establish the basis for the superiority of human cognitive abilities over those of chimpanzees, although 99 percent of their genes are similar to our own. “The human brain has evolved in a way that enhances both cognitive flexibility and imitation, the qualities that shaped our capacity for innovation, other aspects of cognition, art, speech, language, and free will,” he writes. In his zeal, the author sometimes creates straw men out of his chosen opponents, exaggerating and misrepresenting their points of view. Describing himself as an evolutionary biologist rather than a psychologist, Lieberman deconstructs the complex nature of human speech, which depends on unique biological features. A fascinating example is the human tongue, which descends into our throat in the first years after birth, allowing us to enunciate clear vowel sounds while also conferring the disadvantage that we are at risk of choking on food. Offering evidence from CT scans, Lieberman dismisses the notion that language ability is localized in the brain. He calls attention to the role of neural circuits and basal ganglia buried deeply in the brain, which link cortical areas “that act as the brain's sequencing and switching engine.” These circuits, controlled by a specific gene, are present in other primates. Lieberman suggests that it may be the specifically human variant (the FOXP2Human gene), that “supercharg[es] the circuits that confer [our] cognitive flexibility.”

A fascinating though occasionally crotchety scholarly presentation of the relationship among biology, genetics and culture. May be difficult going for some general readers.