Victor McKusick, “Mendelian Inheritance in Man: Catalogue of Human Genes and Genetic Disorders”, 1966 was the topic of an earlier blog post.
Here I present: Joe Tjio & Albert Levan, “The Chromosome Number of Man”, Hereditas, year 1956, volume 42, pages 1-6.
This paper was a cytogenetic publication that accelerated research on chromosomes; because, a biological species has a unique number of chromosomes.
The chromosome number is effectively an identity of an organism.
“Hominine” is the taxonomy group of great-apes & humans (shown ABOVE). Prior to the publication of this paper, it was believed that all “hominine” had the chromosome number of forty-eight (48).
Joe Tjio and Albert Levan, provided that the chromosome number of humans was forty-six (46). The number two (#2) chromosome of humans is a “Robertsonian fusion” of two hominine chromosomes.
In the table ABOVE, the chromosome numbers are given on the right side, 1 to 22, XY. The gene symbols assigned to each chromosome is shown in alphabetical order.
Today, chromosome numbers are equivalent to the genes assigned to that chromosome. Prior, to 1956 and the publication of Tjio-Levan this kind of discussion did not exist.