"In his Prae-Adamitae, published in Latin in 1655 and in English as Men Before Adam in 1656, La Peyrère argued that Paul's words in Chapter 5, verses 12-14 of his Epistle to the Romans should be interpreted such that "if Adam sinned in a morally meaningful sense there must have been an Adamic law according to which he sinned. If law began with Adam, there must have been a lawless world before Adam, containing people". Thus, according to La Peyrère there must have been two creations: first the creation of the Gentiles and then that of Adam, who was father of the Jews. The existence of pre-Adamites, La Peyrère argued, explained Cain's life after Abel's murder which, in the Genesis account, involved the taking of a wife and the building of a city. This account of human origins became the basis for 19th century theories of polygenism and modern racism. This polygenesis of the Gentiles was his method of explaining the existence of the Negroes, Chinese, Eskimos, American Indians, Malays and other people groups being discovered.
"La Peyrère's contentions were soundly refuted by Protestant, Jewish and Catholic authorities. In 1656 after a storm of indignation the Prae-Adamitae was publicly burned in Paris and La Peyrère was imprisoned briefly during a visit to the Catholic Spanish Netherlands, but was released after he supposedly recanted.
"In 19th-century Europe polygenism and Pre-Adamism were attractive to those intent on demonstrating the inferiority of non-Western peoples, while in the United Statesthose attuned to racial theories who found it unattractive to contemplate a common history with non-Whites, such as Charles Caldwell, Josiah C. Nott and Samuel G. Morton, also rejected the view that non-whites were the descendants of Adam. Morton combined pre-Adamism with cranial measurements to construct a theory of racial difference that justified slavery" (Wikipedia article on Isaac La Peyrere, accessed 03-2018).
Digital facsimile from Google Books at this link.