Mapping

The technique of genetic mapping was first described in 1911 by Thomas Hunt Morgan, who was studying the genetics of fruit flies. Morgan was able to study genetic mapping because he was able to actually see traits in the flies (like having white eyes instead of red) that were caused by mutations in single genes. He noticed that some traits violated Gregor Mendel's Law of Independent Assortment (which said that any two loci would segregate independently and thus have a recombination fraction of 0.50).

Genetic mapping did not start being applied to humans until the 1950s, because it was hard to know what traits were caused by genetic mutations. When RFLPs were first described in 1980, a large effort was undertaken to generate maps of all the chromosomes. The first such maps were made in the early 1980s but covered only parts of chromosomes and had only a few markers. Maps of whole chromosomes were made by the late 1980s. By the mid-1990s, as the abilities of the research teams improved, and as the statistical methods of analysis were refined, a number of whole-genome (i.e., covering all the chromosomes) genetic maps were generated. These maps were updated and improved, and they were made available on the Internet.