Genetics of aging is generally concerned with life extension associated with genetic alterations, rather than with accelerated aging diseases leading to reduction in lifespan.The first mutation found to increase longevity in an animal was the age-1 gene in Caenorhabditis elegans. Michael Klass discovered that lifespan of C. elegans could be altered by mutations, but Klass believed that the effect was due to reduced food consumption (calorie restriction).