Who is this riddle? #7. She’s best known for her elegant work on insulin signaling and now works with cat colored by its X chromosome. #longevity 
Indeed, this is Cynthia Kenyon, the pioneering microbiologist, aging researchers and entrepreneur. Her work on Caenorhabditis elegans was instrumental in pushing forward our understanding of aging in model organisms.
Back in 1993, Kenyon discovered a single-gene mutation that could significantly impact the lifespan of C. elegans. Moreover, she showed us that the mutation could be reversed.
Kenyon's discovery helped push a new generation of aging researchers (including me) to intensify the search for an evolutionary-conserved program that influences aging in all organisms — a potential single cause.
Have we now identified that cause?
