Saturday, July 10, 2010

We Are Not Men, We Are Euro Evo Devo

I'm just back from the third biennial meeting of the European Evo Devo society, which was held at the Université Paris 7, parts of which were seemingly designed by Le Corbusier when he was in his SF Dystopian Municipal Car Parks phase. The auditoria were concrete bunkers with no aircon, so anybody who'd borne more than four lectures in a row (the weather was scorchio) came out looking like a decaying lamprey. The meeting for me was made more difficult by my continued sciatica and a persistent head cold which meant that at night I never got more than two or three hours sleep together without waking up amid the sensation of drowning in my own mucus.

But I digress.

What, I hear you cry, is 'Evo Devo'? The term is short for 'Evolutionary Developmental Biology' and it's a science that's waited, ooh, since the early nineteenth century to come into it own.

People of cleverness (the term 'scientist' hadn't been invented) have long wondered about the relationship between development - the course an individual organism takes between egg and embryo and adult - and the grander over-arching evolutionary history of the species to which it belongs. The people who really went to town with this idea were the 'Nature Philosophers', a group of romantics mainly from Germany, and at the turn of the nineteenth century, largely associated with that great polymath Goethe. Now, Goethe's literary effusions are such that he has been referred to as 'The German Shakespeare' but the comparison is hardly fair - after all, the Bard didn't invent the idea of morphology; come up with a theory of colour which, in the importance attached to the observer, presages quantum mechanics, if only poetically; and lay the groundwork for the evo-devo we see today.

The Nature Philosophers felt that the course an embryo follows represents the history of the group to which it belonged, a a kind of record whereby that species would engage in its own striving towards perfection. Yes, it's a lot of waffle, but if the Nature Philosophers had their heads in the clouds (nuages still inhabited by that Goethean offshoot, Rudolf Steiner's Anthroposophists), they had their feet firmly planted in mid air on the ground. Goethe had an immense on Haeckel, and through him, early embryologists such as Wilhelm Roux and from him, a line of experimental embryology that extends right up to the present day.

Despite the noöspheric phooey, the Nature Philosophers were keen observers, and their intellectual descendants pioneered many techniques in dissection, staining and microscopy - all good, solid, investigative stuff. The Nature Philosophers looked at the big questions of the study of form, and tried to devise experiments to answer them.

The impact of Darwinism on this movement was, for a long time, little more than that of a damp lettuce leaf on the hide of a charging rhino. All evolutionary biologists could do was make rather vague and vacuous statements about how various embryological (and thus evolutionary) transformations might or might not have been influenced by selection. This vagueness so infuriated two young biologists, William Bateson and Thomas Hunt Morgan, to such a pitch that they threw over Darwinism in favour of designing experiments to get at the sources of the genetic variation that Darwin could not address. It was Bateson who coined the term 'genetics'. Morgan, on the other hand, with his students, pioneered the use of the fruit fly as a model organism and, through a series of careful experiments, discovered that the units of heredity had physical form, as loci that existed on chromosomes. Bateson went to his grave a pronounced anti-Darwinist; Morgan was only dragged into Darwinism by his students, notably Theodosius Dobzhansky, who managed to fuse the variation he saw in the lab with that he knew as a field naturalist, and has as good a claim as any as being a founder of the 'neo-Darwinian synthesis' we know today.

From the embryologists, rooted in Goethean nature philosophy, we have a comprehensive knowledge of the embryologies of many organisms and how these relate to evolution.

From the geneticists, we got - eventually - techniques to sequence whole genomes and manipulate genes to study the effects of their loss.

The two together have given us evo-devo - a science that uses new techniques of genetics and genomics to answer age-old questions of shape and form in organisms.

Well, that's enough for now, cos I is crackered... I might write more about this in a day or two when I feel better.

The only photo I took in Paris, by way of digressive amusement, was this.

6 comments:

  1. Interesting meeting and interesting your blog, Henry. There was a seminar on the evolution of the Gnathostomata in the meeting?

    So to speak, some clues.

    ReplyDelete
  2. Something like the development (or EVO DEVO, sniff!) of this particular group?

    ReplyDelete
  3. Hi Alejandro - it was a very interesting meeting. I went to a couple of really interesting symposia. One was about the neural crest (and, yes, there was some hot gnathostome action there) and the other was about genomics and the origin or segmentation. Oh yes, there was a third one, about the evolution of the insect head.

    ReplyDelete
  4. Sounds like a fantastic meeting, cromercrox- I'm envious! The neural crest symposium alone would have made it worthwhile.

    On a related note, there was an article by Elinson and Kezmoh that appeared in a recent issue of Developmental Dynamics, on "Molecular Haeckels". I haven't had time to read it thoroughly (and I was completely distracted by the illustrations anyway), but the gist of it is that patterns of gene expression in vertebrate embryos do indeed reflect phylogeny. I've considered blogging the article, but then I've little doubt that it will be the subject of more elevated bloviations soon. I'll just save it for my graduate developmental biology course next spring.

    On an unrelated note: I would be attacked immediately as a "wootard" (or whatever stupid insult is in vogue) on other sites for even suggesting this, but I think you know I'm not a moron or an idiot, and might just hear me out on this. There are a few simple Iyengar yoga poses that can relieve the pain of sciatica, and I know this from personal experience. Not cure it, of course, but relieve (blessedly) the pain. Sciatica is, in large part, an anatomical problem, and Iyengar yoga is based, in part, on anatomical principles, so it's not that much of an intellectual stretch (though it is, of course, a physical stretch). If you don't dismiss this idea entirely, and continue to suffer from sciatica, I suggest seeking out a certified Iyengar yoga instructor ... there are definitely a number of poses that can aggravate sciatica, so it's important to find a teacher who really knows what she or he is doing.

    ReplyDelete
  5. Hi Barn Owl. - I'll be blogging about the symposia in more detail, worry ye not.I think you'd have really enjoyed the symposia. I'll look up the article you mention! As for the yoga stretches and so on, yes, you have a point. My physiotherapist has prescribed me a few simple stretches that do exactly that - they stretch the spine in the relevant area relieving the pressure on the nerve root. And those Other Sites you mention? I don't think one should give them the time of day.

    ReplyDelete
  6. I've just downloaded that Elinson and Kezmoh article ... Thanks so much for mentioning it. It looks like q marvellously original way of illustrating development and I look forward to reading it in more detail.

    ReplyDelete