Page "Hemoglobin" Paragraph 11

There is more than one hemoglobin gene.

The amino acid sequences of the globin proteins in hemoglobins usually differ between species.

These differences grow with evolutionary distance between species.

For example, the most common hemoglobin sequences in humans and chimpanzees are nearly identical, differing by only one amino acid in both the alpha and the beta globin protein chains.

These differences grow larger between less closely related species.