EVOLUTIONARY DIVERGENCE OF HUMAN-CHROMOSOME-9 AS REVEALED BY THE POSITION THE ABL PROTOONCOGENE IN HIGHER PRIMATES

Attempts to solve the fundamental questions regarding the descent of m an are dogged by superstitions and unexamined orthodoxies. The origin of humans, established a decade ago based upon cytological analysis of ape chromosomes, continues to be called into question. Although molec ular methods have provided a framework for tracing the paths of human evolution, conclusive evidence remains elusive. We have used a single ABL gene probe derived from human chromosome 9 to assess the direction of change in the equivalent ape chromosomes. This approach has result ed in a few surprises which again challenge the prevailing view of ear ly primate evolution based solely on chromosome banding patterns. The ABL protooncogene is present on human chromosome 9 at band q34. Simila r DNA sequences presumed to represent an ABL gene, are present on chro mosome 11 in chimpanzee (Pan troglodytes) but at a different relative location, indicating that the mechanism of the origin of human chromos ome 9 is far more complex than has previously been suggested. Neverthe less, in gorilla (Gorilla gorilla) and orangutan (Pongo pygmaeus), the equivalent to human chromosome band 9 q34 is apparently located on ch romosome 13 at a putative telomeric position and no discernible differ ences could be established. Despite the presence of the ABL protooncog ene on human equivalent ape chromosomes, molecular systematics will co ntinue to generate enigmas in the evolutionary context until the entir e genome is sequenced.