At Home With an Evolutionist

THINK BACK to elementary school and that time when your teacher loaded you and your classmates on a schoolbus for a field trip to the Museum of Natural History. You all gathered around some billion-year-old fossil or stood dwarfed beneath a terrifying representation of a brontosaurus, or marvelled at a taxidermist's conception of an extinct dodo bird perched in an artist's conception of its natural habitat while your teacher recited something about the Jurassic Period. And you trotted from exhibit to exhibit, awed and thrilled by them all.

In The Panda's Thumb. Stephen Gould combines a feeling of childlike wonderment with pedagogical earnestness and leads his readers on a fascinating and entertaining field trip through the largest natural history museum of them all--the world. Instead of exhibits, though, Gould presents us with a collection of essays that bring to life the subjects of natural history better than any reconstructed dinosaur of stuffed dodo.

The essays, which Gould selected from among those he has written for Natural History magazine, discuss such far-flung topics as Anglerfish and Mickey Mouse, Lamarckism and tides. The purpose of bringing these diverse subjects together in one volume. Gould tells us in his prologue, is to teach us something about evolutionary theory--no surprise to those who know Gould, professor of Geology, through his course Natural Sciences 36.

The theme, as Gould notes in the prologue, is inherently fascinating; evolutionary theory holds a special appeal for the curious non-specialist. While the field is "sufficiently firm to provide satisfaction and confidence," it is also "fruitfully underdeveloped enough to provide a treasure trove of mysteries." As a science, it encompasses a huge range of approaches and styles from the most abstract to the most particular--"what, if anything, did Tyrannosaurus do with his puny front legs, anyway?" And most importantly, evolutionary theory affects all our lives by addressing where we came from and how we got here.

Gould has selected uniformly amusing and informative illustrations for his theme. In the essay that gives the book its title, he describes a thumb-like appendage on a panda's paw that helps it strip the leaves from bamboo shoots, a panda's favorite meal. The depiction of the panda in its natural habitat typifies the light yet information-filled passages that make this book eminently readable for the non-scientist:

Giant pandas are peculiar bears, members of the order Carnivora. Conventional bears are the most omnivorous representatives of their order, but pandas have restricted this catholicity of taste in the other direction--they belie the name of their order by subsisting almost entirely on bamboo. They live in dense forests of bamboo at high elevations in the mountains of western China. There they sit, largely unthreatened by predators, munching bamboo ten to twelve hours each day.

Moving from bears to mice. Gould devotes one of his essays to an assessment of Mickey Mouse's physical transformation over the 50 years since he first appeared on film. Mickey has not merely failed to age during that time, he has gotten younger-looking. Through intricate scientific analysis--using a pair of precision calipers--Gould determined that Mickey's eyes, head and forehead all became larger as he aged, making him appear younger because large eyes and a bulging cranium are features common in infants. Gould extrapolates from the Mickey Mouse illustration to observe that human beings maintain much of their childlike appearance throughout later life, unlike most other mammals, making us, like Mickey, unique in that respect.

THE SUBJECT MATTER of the book--which includes essays on relative brain size, Down's syndrome, and a mite that dies before it is born, in addition to discussions of cartoon characters--remains entertaining throughout in large part because of Gould's style. He allows us to share his feelings of excitement and wonder about the world of natural history. In "The Panda's Thumb" essay, for example, Gould tells us of his childhood adoration of pandas and how delighted he was "when the first fruits of our thaw with China went beyond ping pong to the shipment of two pandas to the Washington zoo. I went and watched with appropriate awe."

Later in the book, in an essay called "Were Dinosaurs Dumb?," Gould takes us back to third grade and quotes from his textbook, the 1948 edition of Bertha Morris Partker's Animals of Yesterday, which the author admits he stole from P.S.26. Presenting the prevalent view of the huge reptiles, Gould writes.

The discovery of dinosaurs in the nineteenth century provided, or so it appeared, a quintessential case for the negative correlation of size and smarts. With their pea brains and giant bodies, dinosaurs became a symbol of lumbering stupidity. Their extinction seemed only to confirm their flawed design.

But then Gould launches into a spirited detense of the much-maligned creatures, suggesting that their brains, albeit small for their body sizes in most cases, were quite adequate for the kind of life they led.

While Gould the awe-struck and eager little boy serves as the inquisitive force in these essays, Gould the professor steps in to provide scholarly, though never didactic, explanations. In fact, Gould is so careful to avoid sounding technical that he seems more a well-read humanist with a strong interest in evolutionary theory than a scientist who is well-educated in other fields. He refers in almost every essay to such non-scientists as Odysseus, Rabelais, Shakespeare, George Eliot, Alexander Pope, and even Muhammad Ali as bridges to lesser-known scientists like Richard Goldschmidt, Baron Georges Cuvier, Paul Broca, Randolph Kirkpatrick, and Thomas Henry Huxley.

Despite his literary and historical allusions. Gould never comes across as a pedant. Rather, he seems to be a well-rounded scientist with a genuine desire to communicate scientific ideas as effectively as he can--and he succeeds. If Gould had led that elementary school field trip, We'd probably all be studying paleontology today.