SHRINKING THE CAT, by Sue Hubbell, Houghton Mifflin Co., Boston, Mass., 2001, 175 pages, $25.

In “Shrinking the Cat,” naturalist Sue Hubbell offers more of what her loyal readers have come to expect, and less. It’s a book that raises more questions than it answers and may set a record for use of the verb “fiddle” in a nonmusical context.

Think genetic engineering is something new? Hubbell shows that humans have, by their very nature, been “fiddling” with plant and animal species for millennia, long before the existence of genes was known. But, she observes, “What we have never been good at is figuring out the impact, the consequences, of what our skills have allowed us to do.”

The author, a part-year resident of coastal Maine, is beloved for her homey, first-person nature books including “Waiting for Aphrodite,” “A Book of Bees” and “A Country Year.” Her forte is soothing, rocking-chair prose and simple explanations of hard science, colored with a healthy skepticism about scientific progress and an indignant take on the “primacy” of humankind.

In fact, this latter subject is one of the few topics in “Shrinking the Cat” that gets Hubbell’s dander up, in a strangely heated riff about how arrogant and silly it is that humans have named themselves Homo sapiens. “How wise” of our “fine selves” to “define intelligence by holding up other animal minds to ours and to our way of understanding, then dismiss their ways by giving them a lesser name,” she writes.

The impetus for her new book was the beginning in this country of the furor over genetic engineering of food, specifically the introduction of Bacillus thuringiensis into the DNA of corn plants. This natural pesticide kills corn borers, the most destructive insect pest of our largest food crop. Critics of “Bt” corn challenged its safety for human consumption and its potential environmental effects, including toxicity to the caterpillars that become monarch butterflies.

By and large, Hubbell keeps her distance from this and other debates about genetic engineering. Her goal appears simply to put things into perspective by tracing the history of human fiddling with corn and three other common species: cats, silkworms and apples. We learn through these four examples that “the plants and animals we have made or rearranged have given human history a push here and a nudge there and sent it off in new directions.”

The title, “Shrinking the Cat,” refers to one consequence of the domestication of today’s kitties. Around 2000 B.C, humans began selecting for genetic traits such as smaller size to create felines more suited to pethood. And smaller cat bodies meant smaller cat brains. Tabby now has a brain 10 percent smaller than his wild ancestors and is a species unto himself.

The book’s highlights include Hubbell’s wonderful explanation of basic genetics in Chapter 1 and her infectious delight about the surprising genetic similarity of diverse species that has been revealed by modern molecular biology: “All of us – corn, humans, dogs, yeasts, fish, tobacco, and bacteria – are fellows one to another. We are together in this matter of life.”

What interesting tidbits do we learn about corn? Well, beginning about 7,500 years ago, it was developed through careful breeding from a species of grass into a prodigious food plant that is raised to the tune of 10 billion bushels a year in the United States.

Silkworms? One of the most highly engineered species ever, steadily improved to produce more and better-quality silk filaments. The silk trade fueled commerce along the 5,000-mile “Silk Road” between the Mediterranean and China and helped shape the ancient world. Until the advent of rayon and other man-made fibers, the U.S. government promoted the raising of silkworms as a cottage industry, an effort that failed miserably from coast to coast.

Apples? Perhaps the first apple orchard in America was planted in 1604 on St. Croix Island between Maine and New Brunswick. And Johnny Appleseed was a devotee of a religious sect known as Swedenborgianism, whose beliefs in the divine essence of all natural things precluded him from embracing the essential orchardist tools of pruning and grafting.

Among the “unintended, unimagined, and even unknown consequences” of human intervention with these species are corn grown in huge monoculture stands that concentrates pests and diseases and requires extensive chemical treatment; apples that have no taste; and the voracious gypsy moth, a European species imported into the United States in a botched attempt to breed a better silkworm.

Modern corn, silkworms and the hybrid apple varieties available in our supermarkets cannot exist in nature independent of their human cultivators. Cats are another matter, which should surprise no one. “Maybe their famous independence came about because cats met us halfway in the domestication process,” Hubbell writes. “They came to us for the mice … and then allowed us to admire them and take them into our homes.” In other words, cats chose to be shrunk?

None can doubt Hubbell’s sincerity or fail to admire her beautiful and intelligent writing. But, after all is said and done, she dodges the hard issues, including the “problem of limits,” or how 6 billion humans can populate this planet without destroying it. The “Frankenfood” debate about bt corn is addressed in a series of questions such as, “Is this genetic pollution, and if so, what are the implications of that?”

Early in the book, Hubbell asks, “Does the modification of species in the past have anything instructive to tell us about the moral and ethical questions concerning modern genetic engineering?”

Well, maybe. But don’t look for hard answers in “Shrinking the Cat.”

Luther Young, a scientific grant writer at The Jackson Laboratory, is a former science journalist for the Baltimore Sun and co-author of the 1996 book, “Dinosaurs of the East Coast.”