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Cover The stealth model of Alu amplification. It has become widely accepted that the majority of Alu retrotransposition activity in primate genomes has been driven by a relatively small number of high active "master" or source Alu sequences. To date, however, concrete examples of these master elements have proved elusive. In this issue, it is suggested that overactive source alleles play a reduced role in the perpetuation of Alu lineages as compared to "stealth driver" elements that occasionally spawn highly active elements. The basic strategy of these stealth driver elements leaves them less vulnerable to negative selection at the population level. The stealth Alu element, represented by the shadow of the Stealth Fighter aircraft, generates proxy active source elements (represented by yellow Alu RNA secondary structures). These sources in turn generate many additional copies of Alu elements (represented by the blue Alu RNA secondary structures), which typically have little, if any, retrotranspositional capacity. Only the active elements are conspicuous to the "genomic radar" of selection (depicted as blips on the radar screen) and, thus, are purged from the population. In contrast, the stealth driver element and nonactive Alu elements remain undetected and exist under the genomic radar. (Cover illustration by Bang Wong, ClearScience, www.clearscience.info , with concept contributions from K. Han, J. Xing, D.J. Hedges, and M.A. Batzer. [For details, see Han et al., 655–664.])