As I'm sure most of you have heard me complaining (excessively) lately, I'm studying for my stupid prelims. It's hard, but it's actually kind of cool. I like the idea that (theoretically) I'll know just about everything about biology when it's over.
I'm going to write you a little story about how a major field of biology came into being. Namely, the field of population genetics. Who cares about population genetics, you ask? Well, I do. And so does every other biologist in the world, because without the creation of population genetics we probably wouldn't have the unified framework of how evolution works that we do today. It essentially brought together all these contested ideas that were being viciously argued about and showed that instead of being opposite, they were actually complementary. It put an end to incessant bickering among the famous biologists of the time so they could actually get down to work and start discovering some really cool shit.
In the beginning: Darwin came up with this awesome idea about how evolution works. The idea of evolution wasn't completely new at the time (contrary to popular belief) but no one had come up with a real good mechanism about how it works. Remember Lamark - that was one attempt - not an awful one at that, but it did miss the mark at bit. ENTER: natural selection. This was Darwin's pretty revolutionary idea - the idea that individual variations could be passed on to their offspring and the individual's with the "best" variations would have more offspring and so come to dominate the population. That's natural selection in a very small nutshell.
The major problem is, Darwin didn't know how these variations were passed on. At the time, he believed in 'blending inheritance' basically founded on the observation that kids normally look like a mix between their parents. So based on this, theoretically, eventually all these variations that are so important to his theory would disappear because they all get blended together.
DRAMA! So now, we have these biologists at the time who are trying to figure out exactly how this natural selection thing works. In one corner, you have the 'biometricians' (named so because they were very mathematical in their methods) who staunchly believe Darwin's idea that evolution works by the accumulation of small gradual changes. These dudes were right in theory, but they were going about it all wrong because they too, believed in the whole blending inheritance thing.
Now in the other corner you had the 'Mendelians' who rediscovered that funky monk Mendel's work. When they saw Mendel's work about how some alleles are dominant and others are recessive and you get the classic 3:1 ratio of phenotypes they took this to mean that evolution proceeded by leaps and bounds since they thought that a single gene was responsible for each trait. Therefore the only way you can continue to get the variation needed for natural selection is through crazy mutations of huge effect. So they were right about the method of inheritance (alleles don't blend, but are inherited independently) but were wrong about how a trait is only controlled by one gene of huge effect.
These dudes were seriously passionate and way vitriolic to each other in their correspondences. Or at least as mean as you could be way back at the turn of the century. "My dear Mr. Bateson, while I understand your intentions at elucidating the mechanisms of Mr. Darwin's theory are most admirable, I must firmly disagree with your interpretation of your results." Hot shit at the time apparently.
Oh no so what do we do?! The field of evolutionary biology is divided and no one can agree! Will we ever find resolution? Is the Flying Spaghetti Monster really the one responsible for all this?!
Enter our heros, Ronnie Fisher and Sewell Wright Sir Ronnie Fisher was way ahead of his time - he's the guy who basically invented statistics. Seriously, who does that? It's mind-bottling. Obviously, developing the field of statistics was a pretty big step, but more importantly he was the guy who figured out that there really isn't a divide between the Mendelians and the biometricians - they're both right. The Mendelians had the idea about the method of inheritance right, but the biometricians were right about the fact that evolution generally occurs through small gradual changes caused from continuous variation. Fisher was like "Whoa dudes, calm down, let me throw down some knowledge - traits can actually be affected by more than ONE gene (you stupid Mendelians) which creates continuous variation that is NOT blended together (you stupid biometricians)" Absolutely brilliant.
Then Sewell Wright (who actually went to U of I for a year before trying out bigger and better things) figured out that things other than natural selection (ie. drift, migration) could play a role. Wright figured out that genetic drift might be important in evolution as well, mainly based on the fact that not all populations are just these big super-populations but are rather fragmented into smaller sub-populations. That's an important idea, it basically influenced almost all of ecology and had big impacts on the development of the study of speciation. And finally, Wright developed this idea of the 'adaptive landscape' which hopefully anyone with a college biology class under their belt has heard of. Imagine if you will: a landscape covered in peaks and valleys. A group of individuals (or a species or whatever) is hanging out on this landscape. Natural selection works by drawing the species up these peaks which are 'adaptive optima.' In a very simplified way - it's good to be on the peaks and it's bad to be in the valleys. It was a major metaphor at the time that really helped people to conceptualize how natural selection works.
This was the birth of the field of 'population genetics' - or studying how allele frequencies change over time in populations due to the effects of selection, drift, mutation, migration etc etc. There was a bunch of other bros involved, but in my mind, Fisher and Wright were by far the most influential and coolest. Fisher apparently had some serious eye problems and so learned math and calculus just by talking about it and imagining it in his head.
And that's all for this posting of "How Biology Works." Maybe next time I'll talk about how the development of population genetics led to The Modern Synthesis. Another very cool and super important topic that I need to know about. No one really wants to hear me talk about this stuff at the bar, so I figure this is a good place for me to think out my thoughts. Sorry for the nerding =)
