liv-4 was identified in screens for animals with increased stress resistance and longevity; liv-4 is defined by a single mutation that results in animals that are long-lived (Age), slightly long, uncoordinated, form a small percentage of dauers constitutively at high temperature (Daf-c), and display increased thermotolerance; the liv-4 Age and Daf-c phenotypes can be suppressed by a mutation in daf-16, suggesting that liv-4 functions upstream of daf-16 in regulating lifespan and dauer formation.