Imagine a person so exuberant &mdash; all the time &mdash; that nothing gets her down. </p><p>Though this 23-year-old woman comes from war-torn Algeria, where her family has been killed in the civil war, she is perpetually happy.</p><p> Imagine her as a student in a creative nonfiction class at Mesquakie College of Art in Chicago, where she immediately lifts the mood of her instructor and classmates.</p><p> Wouldn&rsquo;t science go to town on her, anxious to discover her difference &mdash; and whether it&rsquo;s marketable? Does any outcome other than driving her to extinction seem possible in our knee-jerk popular culture? In his 10th novel, Richard Powers is again preoccupied with contemporary science&rsquo;s unyielding promise of mastery over human fate.</p><p> Thassadit Amzwar is the happy person in question; hyperthymia, a state of constant happiness, is her condition; and Russell Stone &mdash; who once published a few essays to acclaim but stopped writing after feeling guilt about exploiting his subjects &mdash; is her instructor. </p><p>Stone consults Mesquakie psychologist Candace Weld, a single mother with a 10-year-old son. Soon Candace falls under Thassa&rsquo;s sway, and Thassa becomes the glue binding Russell and Candace&rsquo;s emerging relationship.</p><p>The ingredients of a typical Powers novel, where humanity gets another glimpse at the transcendent, are all in place. In this character-driven novel, Powers&rsquo; empathy extends not only to Thassa, but to the entire frenzied culture, including the geneticist Thomas Kurton who isolates in Thassa what the media quickly dub &ldquo;the happiness gene&rdquo;; the almighty Chicago talk show host Oona (need we identify her?), who helps project Thassa&rsquo;s celebrity worldwide; the well-meaning TV science documentarian Tonia Schiff, who struggles to remain objective; and even the blogosphere&rsquo;s passionate commentators, who turn on Thassa to make her life miserable. </p><p>Rare among our writers, Powers seeks to bridge the science-humanities divide, so that specialists in each sphere become more conversant with the other. Our writers are generally preoccupied with &ldquo;dramatic revelation,&rdquo; as Powers calls it, rather than discursive narration, yet technology drives material conditions, and to a great extent our character. Powers again brilliantly succeeds in incorporating huge chunks of contemporary material experience in his fiction, without sacrificing emotional intensity. </p><p>Powers depicts science&rsquo;s hubris &mdash; exemplified by Kurton &mdash; without condemning its motive; our progress depends on science&rsquo;s idealism. There cannot, of course, be a happiness gene. (&ldquo;The Alzheimer&rsquo;s gene, the alcoholism gene, the homosexuality gene, the aggression gene, the novelty gene, the fear gene, the stress gene, the xenophobia gene, the criminal-impulse gene, and the fidelity gene have all come and gone.&rdquo;) </p><p>The nature-versus-nurture controversy appears in full complexity, the plot shifting around to shed light on different strands of the debate. Both Kurton&rsquo;s utopianism, and the realism of his opponents, are even-handedly presented, to let the reader distinguish between hype and sense in genetics.</p><p>Why do we as readers &mdash; like Russell, Candace and others who touch her &mdash; feel so protective toward Thassa? Do we recognize the power to be happy as too fragile for exposure or analysis? The neatest turn in the novel is toward the end, when new circumstances make us wonder how much of Thassa&rsquo;s happiness is due to sheer force of will; hence the &ldquo;generosity&rdquo; of the title, rather than happiness as a genetic trait.</p><p>Powers has bravely tried to keep up with the enormous pace of change in human civilization. &ldquo;How much are we programmed?&rdquo; Russell asks Candace. &ldquo;Generosity: An Enhancement&rdquo; is yet another thought-provoking stab at the question. Creative nonfiction, in the textbook sense, is rightfully stalled; what we need is bolder fiction, which includes elements of nonfiction in its purview. This is what Powers excels at. </p><p><hr class="infobox-hr-separator" /> <div class="infobox"> <strong>&ldquo;Generosity: An Enhancement,&rdquo; </strong>by Richard Powers (296 pages; Farrar Straus; $25)</p><p></div>