Given that the duplication which produced alpha and beta versions took place half a billion years ago, it will of course not be just our human genomes that show the split, and possess both alpha genes and beta genes in different parts of our genomes. We should see the same within-individual split if we look at the genomes of any other mammals, at birds, reptiles, amphibians or bony fish—for our common ancestor with all of them lived less than 500 million years ago. Wherever it has been investigated, this expectation has proved correct.
