A new species is achieved when two populations of the same living thing become so different that they can no longer breed with each other.
Speciation is the evolutionary process by which populations evolve to become distinct species. The biologist Orator F. Cook coined the term in 1906 for cladogenesis, the splitting of lineages, as opposed to anagenesis, phyletic evolution within lineages. Charles Darwin was the first to describe the role of natural selection in speciation in his 1859 book On the Origin of Species.
Modern Homo Sapien
Mike, you certainly know how to make your point. Loved those examples. <G>
"so different that they can no longer breed with each other" … but you can't blame the sheepherder for trying!.