[Investigation of human cytogenetics for research on human evolution]

The investigation of human chromosomes has become significant in studies of evolution coincidentally with new developments in clinical cytogenetics. Banding pattern and gene mapping allow identification of individual chromosomes and chromosome parts as well as detailed comparisons between Homo sapiens and Pongidae. The most remarkable difference appears in the different diploid chromosome number, 46 in Homo sapiens and 48 in Pongidae, which can be explained through homozygous state for one translocation chromosome evolved from two acrocentric chromosomes. Chromosome rearrangements, which may have phenotypic significance because of positions effect variegations, are discussed as a mechanism of evolution. Within these species chromosomal variability may occur in the form of normal variants or polymorphic parts of chromosomes.