Amongst other work, Van Valen was the first to propose the Red Queen's hypothesis (1973) as an explanatory tangent to his proposed Law of Extinction. The Law drew upon the apparent constant probability [not rate] of extinction in families of related organisms. The data were compiled from the existing literature on duration of tens of thousands of genera throughout the fossil record. He also defined the Ecological Species Concept in 1976, in contrast to Ernst Mayr's Biological Species Concept. In 1991 he proposed that HeLa cells be defined as a new species and be named Helacyton gartleri. As of 2006 he is professor in the Department of Ecology and Evolution at the University of Chicago.
Publications
Leigh Van Valen (1973). A new evolutionary law. Evolutionary Theory, 1:1-30.
Leigh Van Valen (1976). Ecological species, multispecies, and oaks. Taxon, 25:233-239.
Leigh Van Valen and Virginia C. Maiorana (1991). HeLa, a new microbial species. Evolutionary Theory, 10:71-74
