Evolving Thoughts

Basic introduction to homology

From Evolution: Education and Outreach comes a nice introduction to the concept of homology.

Late note: OK, not so good. I saw only the cute pix, and presumed the author understood paraphyly. But as I didn’t have an entirely functional computer at the time I leapt in too soon. See Malte Ebach’s and David Williams’ takedown here. Their point is that paraphyletic groups are formed by what hasn’t evolved, and so they are fundamentally antievolutionary groupings.


  1. #1 MCEbach
    January 21, 2009

    I disagree. It is not a very good paper on homology at all. It is, however, a good introduction to analogy and homoplasy. Pity she missed out paraphyly and polyphyly and other non-evolutionary concepts. The title is very misleading.

  2. #2 Jim Thomerson
    January 21, 2009

    I was likewise not impressed, and agree with the poster above. Why did you think this was good?

  3. #4 TR Gregory
    February 11, 2009

    See Malte Ebach’s and David Williams’ takedown

    Yeah… I wouldn’t exactly call that a takedown. See Nick and RPM’s comments to the posting, with which I agree.

    By the way, why is it about “bringing homology into focus”? Because it is in an issue about eye evolution, and there has been significant debate about whether eyes are homologous (genetics) or analogous (structure). She was introducing the concepts in an accessible manner that other authors (Todd Oakley, Joram Piatigorsky, and I) brought up in some more technical articles. That should have been obvious from the abstract:

    “Anyone who has skimmed a high school biology textbook will be familiar with the iconic examples of homology that seem inseparable from any explanation of the term: the limb structure of four-legged animals, the human tailbone and the more elaborate tail of monkeys, and the remarkable similarities among the embryological development of fish, birds, and humans. These same examples make their way from edition to edition, along with the classic illustration of an analogous structure: the wings of butterflies, birds, and bats. But is that really all there is to say about homologies and analogies? Several articles in this issue discuss these concepts more deeply in the context of eye evolution (Gregory 2008; Oakley and Pankey 2008; Piatigorsky 2008). Homologies and analogies, it seems, are not a black and white issue—especially when it comes to vision. ”

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