In Genome Research this week, Adam Ewing and Haig Kazazian at the University of Pennsylvania report their technique, using high-throughput sequencing "to determine the insertion sites of virtually all members of the human-specific L1 retrotransposon family in any human genome." In assaying 25 individuals at 1,139 sites, and using diagnostic nucleotides, the pair was able to locate "the approximately 800 L1Hs copies corresponding specifically to the pre-Ta, Ta-0, and Ta-1 L1Hs