Lewis Thomas. 193 pages. New York: Charles Scribner's Sons; 1992. $20.00.

In The Fragile Species, Lewis Thomas has collected observations on cherished fascinations: bacteria, termites, genes, and language. Upon these wonderments he supports his thesis that the driving force in nature is cooperation, that evolution has favored symbiosis, and humankind's hope for progress depends on cooperation and communication.

Readers of the National Book Award-winning, The Lives of a Cell, will remember that Thomas' explication of evolutionary biology holds that scientific advancement requires an understanding of how biologic systems work and interact. Dr. Thomas grew up in the heyday of microbiology and immunology that spawned antibiotics and vaccines. He posits that molecular biology, through the technology of recombinant DNA and cell fusion, will unlock the age-old secrets of the cell; an underlying single mechanism for each of the chronic degenerative diseases will be discovered.

Although he is quite aware that "most of what is regarded as high science in medicine is actually a set of technologies for diagnostic precision," he still believes that more basic research is the answer to modern medicine's quandaries: "... the chronic disablements of an aging population ... the escalating costs of health care; and ... the most allusive puzzles in all of biology ... all human cancers".

Two essays, "In Time of Plague" and "Aids and Drug Abuse," discuss the acquired immunodeficiency syndrome pandemic. Thomas is direct, optimistic, and convinced

... that AIDS is, first and last, a problem and a challenge for science ... the only sure way out of the dilemma must be by research ... it is as close to a certainty as anything I can think of in medicine that the AIDS problem can be solved.

At the root of the epidemic of drug abuse, Thomas sees the neglect of public education, the subsequent loss of irreplaceable early learning years, "... the power unique in the brain of a young child," and too many children growing up in an environment with a lack of affection and respect.

Lewis is a scientist—he wonders. How did this species, defined by its ability to communicate, obtain the genes for language? How can children learn "difficult" languages (such as Chinese and English), even several at a time, a task almost impossible for an adult? In seeking the origin of language, he examines the neurologic basis of birdsong, the fossil record of Ur-bacteria, and the etymology of words, but there are too many unknowns. After consulting linguists, and Julian of Norwich, he concludes, in "Communication," that language was invented by children at play.

In a central essay, "Obligations," Thomas asserts that "... we are genetically programmed for social living". We have a moral and biologic obligation to do something for the two thirds of the earth's population shortchanged by the inequities of distribution of the globe's economic and natural resources. The population, especially the children, suffers from lack of clean water, nutrition, and vaccines. The health of the Third World can be improved by plumbing and engineering and a little pharmacy.

In the introspective "Comprehending My Cat Jeoffrey," Thomas is concerned with epistemic and linguistic problems. Taking flight from the bedrock of etymology, he muses on "nature". He begins with the origin and the idea of the word. What is at the center of nature and what do we think about nature? How do things come to be and how do they work? We began as bacteria, simple one-celled free-living bugs that evolved into exquisitely complex people by symbiosis—by learning to live with each other.

His thoughts and writing skip about like Brownian movement. Like a bug skimming, he eventually covers a lot of water and goes deeply into questions that have engaged him and now will puzzle us. He admits it:

I can acknowledge openly that my own mind, is at most times, a muddled jumble of notions, most of them in the form of questions, never lined up in any proper order to be selected and dealt with when time allows, most of the time popping into my head unpredictably and jostling against any other ideas that happen to be floating along, each new disturbance amplifying the disorder of all the others, creating new geometric shapes of chaos imposed on chaos.

He is obsessed by questions and the pursuit of answers and anecdotes; nothing escapes his inquiring mind. He finds examples of cooperation in the hindgut of termites, the trench warfare of World War I, and computer games. He lucidly explains complex microbiologic and biochemical processes with examples that reveal his optimism for humankind's genetic instinctual behavior.