Scientific discoveries are not only cumulative but a bit haphazard. They emerge in reaction to wrongheaded hypotheses as well as from moments of sudden insight. Often they occur inadvertently or by sheer dumb luck. Almost always, despite the genius of their discoverers, they are the product of the long, stubborn investigation of other scientists who remain obscure. Neither James Watson nor Francis Crick would have arrived at an understanding of the double helix without the prior work of Rosalind Franklin at Cambridge, for instance, but their names, and not hers, will forever be associated with that breakthrough.

And there are other even more obscure collaborators. The fruit fly, the evening primrose, and the guinea pig would seem to have little in common. And yet, along with a few other unassuming creatures, they have a just claim to be considered the unsung heroes of biology. As Jim Endersby notes in his fascinating “A Guinea Pig’s History of Biology” (Harvard, 499 pages, $27.95), progress in biology owes as much to the hawkweed and the humble corncob as it does to the brainstorms of scientists. Mr. Endersby has had the happy idea of tracing the successes of modern biological research through the subjects which have made it possible. Each of his chapters focuses on a particular plant or animal, from the now extinct quagga, a cantankerous relative of the zebra, to microscopic bacteriophage, or “bacteria eaters,” and culminating in the genetically engineered OncoMouse®, one of the first rodents with a full-fledged patent all its own. As he points out, “the history of biology has, in part, been the story of finding the right animals or plants to aid the search.”

That search was twofold. It drew on practical considerations: to improve breeding lines, beginning with racehorses but extending to livestock; to develop cash crops with higher yields, culminating in our current, and controversial, genetically modified crops (of which Mr. Endersby provides a cautious and very balanced assessment), and, most crucially, to understand and find cures for devastating diseases. But it was also a search for something fundamental and far more elusive. In Mr. Endersby’s account, the history of modern biology is a story of challenged assumptions, of refusing to accept easy explanations, of a willingness to ask apparently silly questions and to pursue the answers to them with astonishing doggedness.

As Mr. Endersby rather mischievously suggests, certain questions may unwittingly reflect the preoccupations of those who posed them. Why, Darwin wondered, were two sexes needed for reproduction? Certain animals, such as barnacles — as well as most flowering plants — are hermaphroditic. Isn’t self-fertilization safer, less random, and more efficient? Since flowers contain both male and female parts, why is pollination advantageous? Mr. Endersby notes that while he was pondering such tantalizing questions — which led eventually to his theory of natural selection — Darwin was also contemplating marriage. And in 1838, he drew up a list of the pros and cons. He worried about falling prey to “fatness and idleness,” and fretted that matrimony would crimp his book budget. In the end, he decided in favor of marriage; having “a constant companion,” he decided, was “better than a dog anyhow.” One gets the distinct impression that the great man had spent far too much time in the company of barnacles.

Mr. Endersby’s history is enlivened throughout by such anecdotes. One of the most striking involves Francis Galton (1822–1910), one of Darwin’s cousins and the inventor of anthropometry. Galton had a passion for measurement. So overpowering was this obsession that once, while traveling in South Africa, he decided “to determine the precise dimensions of a Hottentot woman’s buttocks.” Since he was reluctant to approach her, he observed his hapless subject with a surveyor’s instruments and then, in his own words, “I boldly pulled out my measuring tape, and measured the distance from where I was to the place where she stood, and having thus obtained both base and angles, I worked out the results by trigonometry and logarithms.”

Whether he is discussing Robert Koch and the development of germ theory or the intricacies of Gregor Mendel’s lifelong research on the genetics of peas, Mr. Endersby presents an admirably lucid explanation of both the scientific issues at stake and of the human and social factors that influenced the course of the research. In his narrative, the scientists, from the explosive J.B.S. Haldane to the flamboyant Barbara McClintock, come to life in all the grandeur of their genius as well as their quite considerable wackiness. At the same time, he never loses sight of the fact that these remarkable figures worked among a throng of silent and involuntary collaborators. Without the primrose, the guinea pig, the zebra fish, and the ear of corn, even the least of life’s secrets might have slipped from our grasp.

eormsby@nysun.com