ABSTRACT In 1929 and 1934–1935, the physical anthropologist Harry L. Shapiro voyaged in the South Seas on the Mahina-I-Te-Pua and the Zaca, measuring mixed-race islanders, including the descendants of the Bounty mutineers on Pitcairn Island. His research in Polynesian hybridity reflects the growing cultural and scientific investment of the United States in the Pacific during this period. Shapiro's oceanic adventures and intimate encounters prompted him to discount typological speculation and emphasize instead the liberal Boasian program in physical anthropology, giving him (...) the confidence to refigure his evaluations of racial difference. The seaborne investigatory enterprise came to influence U.S. racial thought, adding impetus to the condemnation of racism in science. On his return from the South Seas, Shapiro tried to get his fellow physical anthropologists to issue a manifesto opposing the harnessing of their science to racial discrimination and prejudice. (shrink)