A few years ago, biochemist Cynthia Kenyon boldly predicted that much of what we think we know about growing older will turn out to be wrong. The field of aging science, she said, had become resistant to new thinking.

Cynthia Kenyon, professor and director of the UCSF Hillblom Center for the Biology of Aging, did not begin her career with any illusions about changing the world. And yet, she could well succeed in reversing assumptions about how, when, and why we age.

“What I want to understand is why there are differences in life expectancy between organisms,” she says. All organisms started from essentially the same point, but through evolution, the life spans of some increased far beyond others. “Why, for example, do we live longer than worms? If we figure that out, we’ll have enormous power.”

In the early 1990s, Kenyon and her colleagues shook up the field of aging research by demonstrating - through the genetic model Caenorhabditis elegans, a roundworm - that there is a crucial metabolic pathway that influences aging, and that this pathway can be altered, and longevity increased, by manipulating the hormone receptors, signaling proteins, and transcription factors controlling the pathway. Kenyon and others have since proven that the same effect can be achieved in fruit flies and mice.

In 2000, Kenyon cofounded a biotech company called Elixir Pharmaceuticals, hoping to develop a drug that will slow the onset of the aging process, or at least the onset of age-related diseases.

Thanks in part to Kenyon’s research on C. elegans, scientists are beginning to question many widely accepted views on aging.

It was believed, for instance, that aging was not genetically regulated. Common wisdom also held that reduced caloric intake extended the lives of laboratory animals in a passive way; the reproductive system negatively influences aging; and tweaking the genes to alter the process is a zero-sum game in which one biological function is destroyed in the process of boosting another.

By manipulating a few genes, Kenyon and her UCSF colleagues were able to extend the life span of the worm sixfold. And the nematodes suffered no ill effects, contrary to what many of her critics had predicted - they remained vigorous and healthy until late in life. She also found that there is no simple trade-off between reproduction and aging, and that the reproductive system even produces hormones that can extend life.

Kenyon, 52, is not shy about pointing out the differences between her findings and the received scientific wisdom. Nor is she bashful about discussing gonads in mixed company. She has argued that if her male critics were just “brave enough to cut off some gonads” - those of lab animals, that is - they might discover, as she has, that anatomically sound organisms age in the same fashion as those that have been “altered.”

“From the moment I started looking at the data and assumptions about aging, I thought: This just can’t be so,” Kenyon recalls. Unlike, say, Cambridge University geneticist Aubrey de Grey, Kenyon is not necessarily out to crack the aging code so humans can live for hundreds of years. Nor is she keen to take her fight to Washington, DC, to politicize issues of aging and aging research, as some advocates in the field have done. She is, however, eager to explain to lawmakers and healthcare officials that this work deserves more respect and funding. In particular, she says that if certain model organisms can be made to have longer, more disease-resistant lives, there might well be enormous health benefits for humans. She had hoped to join out spoken University of Chicago demographer S. Jay Olshansky on a trip to Washington last year to argue that taxpayers need to spend more on aging research, but her teaching schedule prevented it. (Olshansky testified in September that an investment of $3 billion could produce answers that boost life expectancy by seven years on average.)

Olshansky says Kenyon has played a key role in revealing one or more of the fundamental mechanisms of aging in invertebrates.

“Cynthia’s work has already led to pioneering breakthroughs,” he says. Kenyon’s work and the growing number of contributions from other researchers on aging - many of whom have been inspired by her - have scientists saying something that was barely thinkable just a few years ago: It is conceivable to quadruple, quintuple, even sextuple the life span of certain organisms by tweaking the right genes. Though the influence on the field of longevity in humans is “uncertain,” Olshansky says, “the mechanisms they have identified involve biologically conserved attributes of living things, most probably including humans.”

Critics argue, on a more fundamental level, that Kenyon still has a lot to prove. To that she quickly responds: “Anybody who says that hasn’t seen my worms.”