In previous articles (here and here*), I have argued that understanding phylogenetic trees is a core part of understanding evolution, and thus biology as a whole. My last blogpost emphasized that using terms like basal and early-diverging to refer to taxa misrepresents what phylogenies communicate, and therefore leads to misunderstanding about how evolution works. I would guess that at least some readers thought, "Well is that so bad? So what if I casually talk about a group of species as basal, and some in the audience incorrectly take this to mean less evolved? I just mean to say that they have retained some ancestral character states that I am interested in, and saying 'basal' as a shorthand is convenient."
Here I'd like to stress that contributing to ladder-of-life thinking** with sloppy tree-speaking has real tangible consequences, that we should take seriously, not just as biologists, but as citizens. Today Dan Lowe, friend in political philosophy sent me this article, written by a group of political scientists. They conducted a survey in which they asked 2000 participants (who were all white) to rank how 'evolved' they believe blacks and whites to be using a 0-100 scale placed below a popular depiction of the "ascent of man", an image which undoubtedly stirs up ladder-of-life thinking.***
Thirty-eight percent of the respondents rated blacks less evolved, with rationales including being more 'closer to' or 'like animals'. The researchers report being surprised by these results, but I am not at all surprised. Not just because we know that racism is prevalent in our country, but also because the public understanding of evolution, and particularly common ancestry, is depressingly low.
Anyone who has been taught evolution (including tree thinking) should protest, no humans could ever be considered less 'evolved' than any other! All humans are more closely related to each other than to any other species, so none of us is 'closer to animals'! Anyway, all of us are animals. We belong to a branch of the tree that we call animals, and we are all equally related to other animals. Moreover, it is meaningless and biologically incorrect to consider any group of living organisms primitive or 'less evolved'. The real danger of any suggestion otherwise is that there is some biological or evolutionary rationale for racism. We must be emphatic that there is not.
Right now, many of us are thinking, what can we do to celebrate diversity and support inclusiveness? Here's one thing. We can teach evolutionary biology and teach it well. We can make a point to state that humans are part of evolutionary history just like everything else on the planet and the same principles that apply to other living organisms apply to us, too. Just as we, as humans, are not more 'evolved' than a fern, none of the populations of humans are any more evolved than any other.
p.s. Thanks to Scott Taylor for comments.
p.p.s. Hateful comments in response to this post will be deleted.
*full text versions available from my website
**ladder-of-life thinking = thinking that promotes the idea that some species are more primitive (less 'evolved') than others; is associated with the ladder-of-life or the great chain of being (scala naturae), in which species are ranked from least to most evolved. The ladder-of-life is not consistent with the tree-like structure of evolution. Although it has been rejected since Darwin, the vestiges of progressive thinking remain and are the source of many misconceptions regarding phylogenies.
***I think I am going to have to write a post just about this depiction, and probably I'll make a new version, with a tree and all rotated around, that would have the opposite effect, i.e. stimulate tree-thinking instead of ladder-thinking.