Sunday, January 07, 2007

Carl Zimmer on the Two (Biology) Cultures

C.P. Snow lamented the divide between the Two Cultures - the Humanities and the Sciences, since he felt that they each had so much to offer the other. There is a similar divide in biology - two cultures, representing those biolgists whose work is rooted in natural history, and those whose work is rooted in molecular biology. Biologists who attach cameras to deep-diving sperm whales, who trudge through the rain forest collecting plant species, who hunt whale fossils, work deeply in natural history. They know a lot about ecology, anatomy (plant or animal), cladistics, and the difference between the Devonian and the Permian eras - stuff that someone like me, a biochemist, hasn't studied since college biology. Molecular biologists, on the other hand - live almost completely within the realm of molecules or model organisms. Their expertise is in using very sophisticated experimental and computational tools to understand what goes on at the cellular and molecular level, and they deal with processes and analystical techniques that most natural history biologists haven't studied since their college molecular biology class.

Carl Zimmer, a superb science writer, tackles these two cultures in PLoS Computationl Biology, highlighting how the advent of genome sequencing has driven these two fields closer together - at least in terms of subject matter. Molecular biologists have used their recently developed tools in genomics to venture into territory that has traditionally belonged to natural history - phylogeny, the genealogical relationships among groups of organisms. As a result, there has occasionally been conflict between these two cultures, but Zimmer points out that there is great potential for fruitful cooperation.

My father, a geologist, told me about a seminar he attended recently. The speaker, who might have been a paleontologist, was lamenting the fact that the genomes that have been sequenced exclude key organisms that could shed light on unrseolved issues in natural history. I don't know of any specific examples, because as I mentioned before, my knowledge of natural history is limited to what I learned as a sophomore in college. Most 'biomedical' researchers, including those who run and fund the big genome sequencing centers, are in the same boat. I don't know if they ever seriously consult their colleagues in natural history about which genomes to sequence next. What a great chance for collaboration - those who work in natural history could come up with a list of 15-20 organisms they would like to see sequenced, and the two cultures could work together to produce some real progess on these open questions in natural history. To answer such questions would almost definitely not require complete, thorough (and expensive) coverage of entire genomes - just well-chosen regions. This extensive amount of data, combined with the fossil record, could produce advances in our understanding of key evolutionary events, like the Cambrian Explosion.

One specific advantage of well-chosen genomes suggested by the seminar speaker my father told me about, was the proper calibration of the molecular clock. Biologists who try to put a timeline on evolutionary history are usually not that successful, in some cases producing results that are geologically completely unreasonable. This seminar speaker suggested that we could calibrate this molecular clock much better than we can now, by choosing to sequence certain groups of animals whose fossil record is very well documented. And, importantly, we shouldn't have the molecular biologists try to figure out on their own which groups those are - we should get those who really know the fossil record involved. A well-calibrated molecular clock would be a valuable tool - even outside of studies focused purely on evolution. This is just one potential advantage of greater interaction between these two cultures.

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