The Explaining Gnat

Robert Lee Hotz is a science writer for The Times

Consider the new language of science drawn from the tidal word pools of creation: dissatisfaction, pirouette, timeless, ghost, glisten, gang-of-three, methuselah, bizarre and one most newly minted, bubblegum.

Each of these is the name of a mutant gene linking biology and behavior in an infinitesimal way that poses profound questions of free will and the predestination of biological programming, of flesh and the spirit. Culled from the genome of a fruit fly species called Drosophila, these strings of DNA cause abnormal behavior in an otherwise normal body, ranging from sleep disorders and sexual dysfunction to memory problems and neurodegenerative diseases.

There is perhaps no more controversial scientific endeavor, or one more prone to popular misinterpretation and political misgivings, than the search for the biological origins of behavior, to understand how molecular events in our cells translate into actions, thoughts and feelings.

In the superlative "Time, Love, Memory" by Jonathan Weiner, that quest is embodied in the story of Caltech biologist Seymour Benzer, whose pioneering research in the genetic dissection of behavior puts him at the center of a scientific debate over the biology of human nature. It is an irony not lost on Benzer or his colleagues that they are using a uniquely human invention--the scientific method--to uncover the many ways in which the human species is not unique.

By recounting how scientists like Benzer first identified the heredity of behavior in these tiniest of lab animals, Weiner explores the question that has mystified human thinkers since Galen: What are we born knowing and what do we learn? How much of our behavior is inherited? Are we creatures of culture, as Harvard evolutionary biologist Richard Lewontin argues so eloquently, or of social instinct, as Harvard's E.O. Wilson fiercely contends.

Benzer's research essentially took this debate out of the realm of metaphysical conjecture and made it a matter of controlled laboratory experiment. The result was a provocative blurring of the academic boundaries between biology and culture.

Like Benzer himself, Weiner is much concerned with the intimate philosophical implications of this research and its contemplation of what he terms an inward infinity. Weiner writes: "In one way, this is a parable of the strangeness of life: so much millennial science from such tiny and alien creatures. In another way it is a parable of the unity of life, since not only flies and human beings but everything alive springs from even homelier materials: the same genes, the same atoms, the same clay, the same simple beginnings. In the first view, the whole world looks alien to us; in the second view, there is nothing on earth that is not familiar."

This is both lively biography--Benzer is a Brooklyn-born prodigy whose first microscope was a bar mitzvah gift, a scientist whose calling was first as a physicist, then a molecular biologist--and remarkably absorbing science. Weiner has a rare gift for the poetry of experiment. With sparkle and considerable intelligence, he deftly reanimates the husk of technical discourse with the passion, prejudices and emotional outbursts that make scientific research such a fundamentally human enterprise.

Searching for mutant instincts in fruit flies, Benzer became the first to pinpoint the essential anatomy of behavior. He showed how differences in genes can alter the way creatures conduct themselves.

The time, love, memory of the book's title are, among other things, a fruit fly's inherited traits. The gene called timeless encodes an inability to follow regular sleep patterns. The gene dubbed dissatisfaction makes the female unwilling to conduct a successful courtship. Another mutant, called pirouette, "moves at first in big arcs, then in smaller and smaller arcs, like certain problems in science, turning at last on a single point, until it sometimes starves to death," Weiner writes.

Today, the genomes of such inconsequential creatures are the living texts in which the scientists that Benzer inspired routinely read the abecedary of evolution and behavior. As Walt Whitman observed, "The nearest gnat is an explanation."

In attempting to bridge the evolutionary distance between flies and human beings, however, scientists all too often have over-reached. Benzer, Weiner notes, keeps his own clipping file of over-hyped headlines about behavioral research. Between 1965 and 1995, various studies announced with considerable fanfare the discovery of genes linked to violence, to reading disabilities, to manic depression, psychosis, alcoholism, autism, drug addiction, gambling addiction, attention deficit disorder, Tourette's syndrome and post-traumatic stress syndrome. All of the claims had to be withdrawn.

Benzer's own research findings, focused on fundamentals of time, love and memory, are beyond reproach; yet it would be hard to name another researcher who is more prominent in the scientific community and who also is so unknown to the public.

Weiner, however, is more ambitious on Benzer's behalf.

Benzer himself, now approaching 78 years old, is by no means a closed chapter in the history of science. Known for his nocturnal research habits, he still prowls the second floor Fly Room after midnight in Caltech's Church Hall. Not so long ago, he discovered a gene, called methuselah, that made mutant fruit flies live almost half as long as a normal fly, prompting speculative headlines about its import for human aging.

More recently, news of his newest discovery--the genetic mutation called bubblegum--was made public last month in the journal Science. With Caltech colleague K.T. Min, Benzer identified in the fruit fly a gene that seems to cause a neurodegenerative disorder similar to ALD (adrenoleukodystrophy) in humans. The mutant flies, like the human patients, responded favorably to the mixture of unsaturated fatty acids known as "Lorenzo's Oil."

If Weiner errs by lionizing Benzer too much (it is important to note that Benzer is one of a number of major figures in a much broader century-long effort to unravel the heredity of humankind and the chemical unity binding all living things), it is a sin committed on behalf of one who has done so little in his own lifetime to court fame or seek personal profit that it almost seems forgivable.

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