In a previous article I declared the kalash to be white, even though they diverged from whites 12,000 years ago and are more genetically unrelated to whites than whites are to non-white Caucasoids. Commenter “Some Guy” wrote:
I assume you wouldn’t group together two different species as one just because they had a similar phenotype Pumpkin, isn’t it a bit strange to do the equivalent with races/subspecies?
Some scientists (not all and perhaps not most) do group different species together into the same taxon based on phenotype. A good example are reptiles. Note in the below evolutionary tree, crocodiles and snakes are both reptiles, but birds are not, even though crocodiles are much more closely related to related to birds than to snakes. Thus the grouping is based on phenotype, not lineage.
However no scientist would ever classify bats as a type of bird even if their phenotypes were 100% identical (which they’re not).
Do any of my readers grasp the subtle difference between the two trees that makes it okay to lump distantly related but phenotypically similar species together in some cases but not in others? I’ve mentioned it before but people often ignore me. 🙂
So now that commenter Lerenzo (and perhaps Austin Slater) grasped the difference, I can now make it explicit.
It’s NEVER okay to lump genetically distant species together (no matter how similar the phenotype) if they form a polyphyletic group but some scientists feel it’s okay if they form a paraphyletic group. Of course everyone agrees it’s okay if they form a monophyletic group.
The reason polyphyletic groups are not okay no matter how phenotypically similar they might be, is probably that their similarity has independent origins. By contrast phenotypic similarity in both monophyletic and paraphyletic groups is inherited from a common ancestor.
Unfortunately many scientists today even reject paraphyletic groups and treat all monophyletic groups as taxa regardless of phenotypic diversity. This has led to absurdities like humans being called apes, birds being called dinosaurs, and Andaman Islanders being denied their blackness.