ABSTRACT
As immunological distances are a rough measure of protein (and, therefore, genetic) similarity, the first use of these data involved primate phylogeny and established that the African apes (chimpanzee and gorilla) are more closely related to humans than to orangutans. Another method that became available in the 1960s was the direct sequencing of the amino acids composing specific proteins, a more direct reflection of the genetic material. Protein-sequence data not only confirmed the immunological results, but also showed that humans,
chimpanzees, and gorillas were genetically more similar to one another than had previously been imagined.
