A test of the karyotypic fissioning theory of primate evolution.

Karyotypic fissioning theory has been put forward by a number of researchers as a possible driving force of mammalian evolution. Most recently, Giusto and Margulis (BioSystems, 13 (1981) 267-302) hypothesized that karyotypic fissioning best explains the evolution of Old World monkeys, apes, and humans. According to their hypothesis, hominoid karyotypes were derived from the monkey chromosome complement by just such a fissioning event. That hypothesis is tested here by comparing the G-banded chromosomes of humans and great apes with eight species of Old World monkeys. Five submetacentric chromosomes between apes and monkeys have identical banding patterns and nine chromosomes share the same pericentric inversion. Such extensive karyological similarities are not in accordance with, or predicted by karyotypic fissioning. Apparently, karyotypic fissioning is an extremely uneconomical model of chromosomal evolution. The strong conservation of banding patterns sometimes involving the retention of identical chromosomes indicates that ancient linkages of genes have probably been maintained through many speciation events.