Defining the human species
Having read “Humans benefited by interbreeding” (SN: 10/8/11, p. 13), I wonder if I have missed what, to me, seems a major change in the definition of “species.” I was taught that the attempted crossbreeding of animals of two different species could result in either no offspring or sterile offspring.
If modern humans carry genetic information from Neandertal and Denisovan ancestors, stemming from successful interbreeding that resulted in fertile offspring, why aren’t the Neandertals and Denisovans considered to be merely of a different race or breed rather than of a different species?
Alice Grover, Southbury, Conn.
Some anthropologists regard Neandertals as a subspecies of Homo sapiens and see the genetic evidence of limited interbreeding as supporting that vi