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Re: Tree-thinking (was: they keep on growing despite early fusion)

Also see this forthcoming paper:


Anthropocentricisms in cladograms
Journal Biology and Philosophy
Publisher       Springer Netherlands
ISSN    0169-3867 (Print) 1572-8404 (Online)
DOI     10.1007/s10539-007-9102-x
Subject Collection      Humanities, Social Sciences and Law
SpringerLink Date       Tuesday, December 11, 2007

Hanno Sandvik1 Contact Information
(1) Department of Biology, Norwegian University of Science and Technology (NTNU), 7491 Trondheim, Norway

Received: 29 June 2007 Accepted: 5 November 2007 Published online: 11 December 2007
Abstract Both written and graphic accounts of history can be biased by the perspective of the historian. O’Hara (Biol Philos 7:135–160, 1992) has demonstrated that this also applies to evolutionary history and its historians, and identified four narrative devices that introduce anthropocentricisms into accounts of phylogeny. In the current paper, I identify a fifth such narrative device, viz. the left– right ordering of the taxa at the tips of cladograms. I define two measures that make it possible to quantify the degree of anthropocentricism of cladograms, the human attention score and human rightness score. I then carry out an analysis of the presence of the different distorting mechanisms in phylogenetic textbooks. I deliberately chose two textbooks that adopted a cladistic perspective, since their authors can be assumed to be more conscious about the aim of avoiding anthropocentricisms. Three of the narrative devices are thus absent from cladistic works. However, there is a weak tendency that the resolution of cladogram branches is biased in favour of Homo sapiens. Furthermore, the human perspective is clear and highly significant in the positioning of taxa along the left–right axis of cladograms. I discuss the reasons for and implications of these biased presentations.

Keywords Anthropocentricism - Anthropocentrism - Cladogram - Evolutionary tree - Phylogeny - Tree balance

On 28/01/2008, at 6:36 AM, Sarah Werning wrote:

The following snippet of this thread reminded me that I was planning
to recommend an article about tree-thinking to the list:

Baum DA, S DeWitt Smith, SSS Donovan. 2005. The Tree-Thinking
Challenge. Science 310 (5750): 979-980. DOI: 10.1126/science.1117727

The article found that many people, including many professional and
academic biologists, interpreted the relationships in a phylogenetic
tree by reading of the tips from left to right, rather than reading
the pattern of the clusters. The article clearly explains some of the
more common mistakes people make when reading trees, and also includes
two self-quizzes to help you test your tree-thinking abilities. I
found it to be an excellent teaching resource for my Evolution
students (who found it very clear and easy to read), and other TAs
have found it useful even in their Intro Bio courses. I also found it
helped me in teaching, because I could better anticipate the questions
and problems my students would have.

Best of all, Science has made this article (and its SI) available free
for everyone to download, regardless of their subscription status. You
can access it by going to the Tree-Thinking Group's website at:


Especially if you're new to phylogenetics, I think this article would
be a helpful read. But even if you've been doing this for a while,
there's still plenty to learn. I'm not trying to call anyone out as a
bad tree-thinker; I just figured some people might be confused by this

Another great resource for people interested in learning more about
phylogenetics is:



On 1/27/08, David Marjanovic <david.marjanovic@gmx.at> wrote:

Because this one has Pterosauria as the sister-group to the rest of
Archosauromorpha (fig. 17 and p. 154).

But also next to Lepidosaurs and far from Euparkeria + all other archosaurs.

What do you mean by "next to"? The pterosaurs are next to the rest of
Archosauromorpha in that figure, and Archosauromorpha as a whole, including
the pterosaurs, is (by definition) next to Lepidosauromorpha (which still
included the younginiforms).

Check the entirety of the literature. For all its faults, this is the one
and only time Lepidosaurs have NOT been excluded from consideration.
Benton 1985 was a breakthrough and a one-time-shot. Also, perhaps, an
unfounded embarrassment, because Benton dropped Lepidosaurs from all
subsequent lists. <<<<

Sure, the lepidosaurs are fairly close to the pterosaurs in that matrix, but
the archosaurs are _even closer_. While far enough from the orthodoxy (i. e.
Pterosauria _within_ Archosauria, or, as Benton called the crown- group,
Neoarchosauria), it is still closer to the orthodoxy than to your
hypothesis. That is my point.

Sarah Werning
reply to: swerning@berkeley.edu
Museum of Paleontology and Department of Integrative Biology
University of California, Berkeley
1101 Valley Life Sciences Building
Berkeley, CA 94720-4780

-- John S. Wilkins, Postdoctoral Research Fellow, Philosophy University of Queensland - Blog: scienceblogs.com/evolvingthoughts "Darwin's theory has no more to do with philosophy than any other hypothesis in natural science." Tractatus 4.1122