Friday, January 30, 2009

Evolution and Art

I believe it was on the first day of this class, that Dr. Fox said something to the effect of:
Evolution affects every subject, with perhaps the exception of art...

After recently finishing a semester of studying art history, I wasn't sure this was true. I wanted to find this link. Last night I found it in the most unlikely place, "The Colbert Report".

Stephen T. Colbert's guest on January 28th 2009, was Dennis Dutton, who says that the appreciation of art has evolved as an evolutionary trait. He has written a book on why art is related to human evolutionary history called "The art of instinct".

You can see the episode on the CTV broadband network, under The Colbert Report.

Natural Selection VS Religion - Response to e-mail

In response to Mike's e-mail:

Thanks for the readings Mike, I will certainly go over them this weekend.

To add another angle to this look at the tense relationship of Darwin and Religion I would suggest some light google searching on some of the legal trails about teaching natural selection in the classroom. 

The classic historical case is the Scopes trial of 1926. Here, high school teacher John Scopes was charged by the State of Tennessee with breaking the "Butler Act"; which made it illegal "to teach any theory that denies the story of the Divine Creation of man as taught in the Bible, and to teach instead that man has descended from a lower order of animals". There are many websites that give different slants on the trail. Search "Scopes Monkey Trial" and you can pick what you wish to read.  

There have also been more recent trails using the "bacterial flagellum argument" in place of the 1800s "watchmaker/eye argument" see
or watch this very good lecture by Dr. Kenneth R. Miller at Brown University and this more instructional animation of hypothesized and tested steps.

There have also been earlier public arguments like that between T.H. Huxley and Bishop S. Wilburforce at Oxford. I heard a funny recreation at Down House, it went something like this.

Above Pictures: Plaque designating Down House as an English Heritage Site (left); Darwin's gardens (right). Those hundreds of cabbages he mentions in chapter 3, they are still there.

A suggested reading for 02/04/09

As Josh notes, next week's supplementary reading is a very famous and controversial article that drew many responses. I highly recommend this 1996 American Scientist article from architectural historian Robert Mark, critiquing the use of the 'spandrel' metaphor by both Gould & Lewontin and their critic Daniel Dennett.

supplementary reading for 02/04/09

A classic paper from Gould and Lewontin.

Gould, SJ and RC Lewontin. 1979. The spandrels of San Marco and the Panglossian paradigm: a critique of the adaptationist programme. Proceedings of the Royal Society of London. Series B. Biological Sciences 205 (1161):581-598. (available at a lot of places as PDF, here's a copy from University of Illinois: Urbana-Champaign)

This paper isn't on the official menu but I think it's a good quasi-contemporary review of the Gould and Lewontin paper (as borrowed from the reading list of the evolutionary biology course I took once upon a time...)

Pigliucci, M and J Kaplan. 2000. The fall and rise of Dr Pangloss: adaptationism and the Spandrels paper 20 years later. Trends in Ecology and Evolution 15 (2):66-70 (pdf available here)

Wednesday, January 28, 2009

Further thoughts on Chapters III-IV

1. As an ecologist, I'm in total agreement with John Whitfield at Blogging the Origin when he says that reading Chapter III engenders the feeling that there's nothing new under the sun. An old joke in philosophy is that all philosophy is footnotes to Plato. After reading chapter III of the Origin, one could be forgiven for thinking that all ecology is footnotes to Darwin.

2. Chapter IV also has plenty of prescient bits, my personal favorite of which is the passage on p. 113 stating that it has been 'experimentally shown' that diverse mixed plots of grass will be more productive than plots sown with one species. The diversity-productivity relationship has been the subject of intensive recent research, and broadly speaking, Darwin turns out to have been right: more diverse plots are more productive. But the underlying mechanisms have been controversial (at least they were for a time). The main issue is/was how to distinguish between an effect of diversity per se on productivity from the effects of particular species (all else being equal, a more diverse plot is more likely to contain a dominant, highly-productive species). In my own work I've helped develop a solution to this issue. Interestingly, the solution is based on George Price's work on the mathematics of natural selection (see Fox 2005). Briefly, dominance of a mixed plot by a highly productive species turns out to be formally analogous to the increase in frequency of a trait favored by selection. We can use Price's mathematics to factor out this effect, leaving a remainder that isolates the effect of 'diversity' per se on productivity. So this little subfield of research has come full circle: Darwin raised the example of the diversity-productivity relationship because of its implications for his evolutionary ideas; it now turns out that Darwin's evolutionary ideas have implications for understanding the diversity-productivity relationship. Not sure how interesting this is to anyone besides me, but I assume if you've read this far you found it at least mildly interesting... ;-)

3. A historical note related to #2: Darwin doesn't cite the experiment to which he was referring, but my friend and former colleague Andy Hector recently identified it. It turns out to have been, as far as we know, the very first 'ecology' experiment ever conducted, predating Haeckel's coining of the term 'ecology' by several decades. See Hector and Hooper 2002 Science 295:639-640 for this interesting historical nugget.

4. Given Darwin's prescience in so many areas, I was a little disappointed to see that his theory of the origin of species relies so heavily on the principle of divergence of character (i.e. you'll be fitter if your offspring are more variable). It certainly wouldn't have been beyond Darwin to have thought up more modern ideas, such as that widespread species often comprise geographically-separated subpopulations living in different environments and therefore subject to different selection pressures, which will drive them apart in the long run as long as rates of gene flow among subpopulations are sufficiently low. I was expecting to see a clear statement of this idea, and I never did. EDIT: whoops, Darwin does indeed hit on this idea. On pp. 107-108 he refers to subsidence converting a continent into large islands, thereby isolating separate populations of the same species. And then he says "...after physical change of any kind, immigration will be prevented, so that new places in the polity of each island will have to be filled up by modifications of the old inhabitants; and time will be allowed for the varieties in each to become modified and perfected." And of course, this passage is a summary of what has come before. I suppose I missed it because Darwin often intermingles this idea with other distinct but related ideas (e.g., on p. 103, when he talks about the spatial scales on which we should expect to see variation within highly-mobile species like birds vs. less-mobile species).

5. The later parts of chapter IV (pp. 116-130), on the 'tree of life' and the problem of classification, was interesting to me as proposing a solution to a problem that, as modern readers, we don't even recognize as a problem. The Linnean system of classification is hierarchical: species are nested within genera, which are nested within families, etc. What justifies (or maybe better, 'motivates') a hierarchical classification system? After all, there are many non-hierarchical possibilities. One could, for instance, group organisms into 'functional groups' based on their ecological 'roles' (e.g., herbivores, carnivores), and these groups would not be hierarchical but rather overlapping (e.g., some organisms are both herbivorous and carnivorous). I'm sure that various non-hierarchical classifications schemes were proposed at some point in the history of science (anyone know anything about this?). But if all life really does comprise a single branching evolutionary 'tree', that's a strong motivation for choosing a hierarchical classification system which reflects the hierarchical nature of 'tree-like' branching. This gets to philosophical issues regarding 'natural kinds'. Nature is full of variable 'things' that are similar in some respects and different in others. Is there ever a 'natural' way to classify these things, to 'cleave Nature at the joints'? Or is classification merely a human construct, something we do strictly for our own convenience?

Monday, January 26, 2009

supplementary paper for this week

Price, GR. 1995. The Nature of Selection. Journal of Theoretical Biology 175(3):389-396. (pdf here)

At the end of this course I will add in all of these links into the main supplementary readings post down below. Somewhere. Down there.