One point that emerges from the studies of programmed cell death in C. elegans and other organisms is the striking similarity of genes and gene pathways among organisms that are as superficially distinct as worms and humans. Many studies over the past 10 or so years involving C. elegans, yeast, the fruit fly Drosophila melanogaster and other simple organisms have repeatedly led to analogous findings concerning evolutionary conservation and have established one of the most striking themes of modern molecular biology. I like to refer to this theme as “The principle of biological universality,” and it underlies my strong conviction that the rigorous, detailed and analytic study of the biology of any organism is likely to lead to findings of importance in the understanding of other organisms, including ourselves.