[
Nature,
1999]
Life is based on social contract, genes work for the good of the organism, and they are reproduced. But certain rogue genes, called transposons, wantonly reproduce at the expense of the organism, inserting new copies of themselves all over the genome. Reporting in Cell, Tabara et al., and Ketting et al. now show that organisms have systems to hold transposons in check. They suggest that one of the clues that organisms use to detect illicit activity is double-stranded RNA, and their results could explain the reason for the mysterious phenomenon of RNA interference.