About Rationally Speaking
Rationally Speaking is a blog maintained by Prof. Massimo Pigliucci, a philosopher at the City University of New York. The blog reflects the Enlightenment figure Marquis de Condorcet's idea of what a public intellectual (yes, we know, that's such a bad word) ought to be: someone who devotes himself to "the tracking down of prejudices in the hiding places where priests, the schools, the government, and all long-established institutions had gathered and protected them." You're welcome. Please notice that the contents of this blog can be reprinted under the standard Creative Commons license.
Saturday, October 07, 2006
Evolutionary novelties, if you believe in that sort of thing
The area of evolutionary biology currently studying novel traits is often referred to as “evo-devo,” which stands for evolution of development. The basic idea is that if we are to understand how, say, wings evolved as modifications of the front limbs of some groups of vertebrates (like birds), the answer must at least in part lie in an understanding of how development (the set of changes from embryos to adult forms) itself evolved.
The talks I have heard so far vary from studies of the evolution of hormone-receptor biochemical functions to how horned beetles get their horns, from the evolution of eyespots on butterflies' wings to that of new biochemical capabilities in bacteria like E. coli, and from how humans evolved big brains to why male and female flowers can be different from each other even though they share the same genes. This is a spectacular range of topics, and a feast for the brain of even mildly curious scientists (and most scientists are much more than just mildly curious about these sorts of things).
The keynote lecture that opened the symposium was delivered by Mary Jane West-Eberhard, of the Smithsonian Tropical Institute in Costa Rica,author of “Developmental Plasticity and Evolution.” West-Eberhard explained how organisms' developmental systems are flexible enough (plastic, in technical terms) to be able to accommodate to many external environmental stresses and even genetic defects, rapidly producing adjustments that allows them to survive and that can then be favorably selected during the course of evolution, resulting in the appearance of novelties. One of the most spectacular examples she presented was the case of a macaque (a not-too-distant relative of humans) who was born without the use of its forelimbs. The animal's developmental system was able to adjust its skeleton, muscles and even behavior, turning the monkey into a bipedal organism, something that has always been considered a crucial and difficult to explain step in human evolution. The picture of the mutant macaque shown by West-Eberhard (right) is in fact quite disturbing, this guy doesn't look that different from some people I encounter in the New York subway...
The symposium will close tomorrow, and yours truly will also present a talk by the title “What, if anything, is an evolutionary novelty?” which is already available on my web site.