The DAF-16 gene in nematode worms such as C. elegans is thought to be the fulcrum of a metabolic feedback loop that switches between long-lived stress resistant and short-lived reproduction focused states. "Ageing is a process that all organisms experience, but at very different rates. We know that, even between closely related species, average lifespans can vary enormously. We wanted to find out how normal ageing is being governed by genes and what effect these genes have on other traits, such as immunity. To do that, we looked at a gene that we already knew to be involved in the ageing process, called DAF-16, to see how it may determine the different rates of ageing in different species. ... Researchers compared longevity, stress resistance and immunity in four related species of worm. ... They also looked for differences in the activity of DAF-16 in each of the four species and found that they were all quite distinct in this respect. And, importantly, the differences in DAF-16 corresponded to differences in longevity, stress resistance and immunity between the four species - in general higher levels of DAF-16 activity correlated with longer life, increased stress resistance and better immunity against some infections."