Charles G. Sibley advanced a very controversial methodology to compare the DNA of differing species. Sibley initially attempted to determine the extent of genetic differences between bird species--but his work was ultimately expanded to characterize the differences between chimps, gorillas, and humans. In contrast to previous studies that indicated that chimps, gorillas, and humans were all equally distant from each other (each was a genetically distinct line from a common ancestor) within phylogenic classifications. Sibley's methodology indicated that humans were closer to chimps in terms of DNA or gene content.

Sibley initially developed a genetically based system of bird taxonomy. In conjunction with Jon Ahlquist, he pioneered a new technique to create DNA-DNA hybridizations in order to determine the evolutionary relationships among birds. Sibley's objective was ultimately to devise a methodology to determine how similar the DNA of one species is to that of another species. The more...