Dr. Ruvkun has shown that insulin-like pathways regulate longevity and metabolism in C. elegans. His genetic analysis indicates that the keys to longevity in C. elegans insulin-like signaling are the targets of the transcriptional factor DAF-16, a factor that has human homologues. Additionally, Dr. Ruvkun performed what he described as the first reported comprehensive functional genomic screen for longevity genes. By screening 5,690 C. elegans genes using RNA interference (RNAi), he found that genes important for mitochondrial function appeared critical for determining C. elegans lifespan. A concurrent classical genetic screen also identified a mutation affecting mitochondrial function that increased lifespan. The animals with impaired mitochondrial function and extended lifespan had reduced ATP content and oxygen consumption rates, which indicate altered metabolism. This suggests that there is a complex relationship between metabolism and longevity.