“Nothing in Biology Makes Sense Except in the Light of Evolution” – Theodosius Dobzhansky
Dobzhansky’s sentiment, or something like it, gets invoked frequently in these debates. It’s the sort of sentence that sounds good but its meaning is very hard to pin down. For starters, what does Dobzhansky mean by “nothing”? Is it that you need evolution to explain, say, the circulatory system? Did On the Origins of the Species reveal something we didn’t previously know or understand? What about the fact that the basic mechanisms of the circulatory system were discovered centuries before Darwin was even born? More generally, many fields of biology developed completely independent of the theory of evolution. Human anatomy, cell biology, and molecular biology all advanced without much input from Darwin’s insights.
Evolution simply does not play the same role in biology as Newtonian Mechanics does in physics. Newtonian mechanics really is “the foundation” in physics. Pretty much everything we’ve done since the mid-1600’s is based in whole or on part on Newton’s work. You can’t teach even basic physics without Newton. You cannot do physics research without understanding Newton. My PhD thesis on space plasmas had Newton’s 2nd law in Chapter 2. Biology is nothing like that. To reiterate for the umpteenth time…you don’t need evolution to practice medicine! Biology as a science is balkanized, and the various fields developed independently rather than sequentially. Evolution is not the “foundation” of biology.
The tragic irony here is that scientists who suggest otherwise are committing the cardinal sin of describing the world as they want it to be rather than how it is.
Great post. I’d love to talk to Dobzhansky to see what he means, as well. Extreme statements in general are hard to defend. Do you think he means how any biological part or function came to be, rather than how it works? Not sure.
Anyway, great post. I love the length. I have a lot to learn!
Thanks for the comment Victor! I think a lot of statements like these are meant more to draw battle lines and signify which “side” you’re on rather than as a substantive statement on, say, knowledge production in biology. Nothing wrong with tribal statements of course. I do it myself sometimes:-)
I’d argue that evolution is to biology as orbital theory is to chemistry. You can, in fact, be a pretty good chemist without understanding orbitals. The periodic table was drawn up before we knew that there was 1 s orbital and 3 p orbitals, and that’s why there’s this overall structure where elements are grouped into pairs and sextets and so on. But… I would have some serious qualms about hiring an orbital-skeptic as a research chemist. They would be learning by rote things that could be understood with the underlying theory.
To give an example on the biology side: there was a protein that my lab studies. We had a wall that had the genetic code for that protein from a dozen different species, where each codon was color-coded for “complete agreement across all species” to “random assortment”. We used this wall all the time to pick research targets: highly conserved sequences are likely to be important for function, non-conserved sequences are likely to be non-active filler. We weren’t an evolution lab, but this wall was both an example of evolution (sequences were more similar for more closely related species) and an application of evolution. I guess we didn’t need to _believe_ in evolution to use this method, because God could decide on sequence conservation the same way that evolution could… the same way one wouldn’t need to understand orbitals to be able to work with the periodic table… but yeah, that would be a pretty serious flaw that might in some cases lead to missed insights.
I’ll post more thoughts in a more recent post…
Brilliant! Thanks for this. *Very* helpful. Have to think about it more later b/c I’m working now. But quick response. I agree you may not want someone in a biology lab if they don’t believe in evolution (but as you yourself noted, it’s not always that straightforward). However…what about a physics lab? Or a EE lab? Or a medical doctor? Or an accountant? We (in the scientific community) make the very specific claim that rejecting TOE impacts all of these other things.