Ernst Mayr

1904 - 2005

Species and Speciation

Before one can consider the next species following Homo sapiens, it is first necessary to have some idea as to what we mean by the word "species" and how new species develop—what we call "speciation."

Ernst Mayr dominated this discussion for most of the 20th century. He was the foremost taxonomist of that period. His definition of "species" involving natural interbreeding populations within an ecological niche stressed reproductive isolation as a key part of the definition. That is, the inability to breed with other closely related species was necessary in defining a species. He also developed key concepts of speciation related to natural barriers to interbreeding—what we call allopatric speciation. His theories were widely accepted for most of the century. However, by the end of the 20th century, multiple competing definitions of both species and speciation have been developed with the advent of greater understanding of the genome and mechanisms of genetic variation as well as more complete and precise observations of species in their natural environment.

This has led to what we now call the "species problem" in trying to get agreement on exactly what constitutes a species and when to lump or split groups of similar organisms into one or more species. There is ongoing debate as to whether species are "real" in the sense of having some existential observable external reality versus being arbitrary concepts in the minds of Homo sapiens. All of these issues are discussed in the book. One cannot talk about a successor to Homo sapiens without first agreeing on what a species is and understanding how speciation occurs.

Click on links to other players in my journey below.