Mutants

Starred review from September 22, 2003
In a book that's as disturbing as it is enlightening, as unsettling as it is compelling, Leroi examines all sorts of genetic variability in humans and explains how that variability helps scientists understand the processes associated with human growth and development. Leroi, recipient of a Scientist for the New Century medal from the Royal Institution of Great Britain, demonstrates, in both text and pictures, that an enormous amount can go wrong as humans develop from fertilized eggs and progress toward old age. The missteps can result from genetic or environmental causes, with the latter occasionally responsible for the former. Although the subjects Leroi presents—conjoined twins, individuals with cyclopia (a single eye), deformed or missing limbs, abnormal height, supernumerary breasts, an overabundance of body hair, piebald coloring—often appear grotesque, he approaches all of his topics and each of his human subjects with great respect. Leroi uses each example to demonstrate the developmental lessons they illustrate: e.g., the role of fibroblast growth factors in the formation of limbs, the pituitary's impact on body size. By explaining that each of us carries hundreds of mutations within us, he asserts that we are not all that different from those who, on first glance, appear very disparate. Similarly, he effectively dismisses the belief that human races are anything more than a convenient social construct, establishing that there is no biological basis for such categorization. While the graphic pictures might deter some, they add immeasurably to the text.