Here's a transcript of the first part of a mock job talk that I gave for the Lehman College Philosophy Club this afternoon. The content is drawn from the first chapter of my dissertation, whose proposal was recently approved.
I'm posting this here so that friends and family can have some idea of what I'm studying without having to suffer through my awkward, stumbling attempts to summarize three years' worth of research in fifty words or less. Comments are welcomed and encouraged.
The second part should follow tomorrow night.
Good afternoon. Thank you all for coming. Before I begin, I’d like to thank Professor Jensen for giving me the opportunity to speak in this series. I’d also like to thank Professor Pigliucci for bringing the series to my attention.
I’ll start today with a quote from one of the most important biologists of the past century. Theodosius Dobzhansky once said that nothing in biology makes sense except in light of evolution. What this means in practical terms is that every presentation about biology these days absolutely must begin with a slide explaining who Darwin was and describing his theory of natural selection. Let’s get that out of the way first.
I’m just going to give a quick overview of the theory of natural selection. When Darwin first published The Origin of Species in 1859, there were already plenty of naturalists who accepted the idea of evolution. What set Darwin apart from those other naturalists was the mechanism by which he said evolution occurs: natural selection. The theory of evolution by means of natural selection says that whenever you have a population of individuals with variable traits—some are taller than others, stronger, faster, some may have stripes and others are solidly-colored, what have you—and individuals can pass their traits on to the next generation—for example, a tall father breeds a tall son—and these individuals are in competition for some sort of resource, it follows that succeeding generations will have greater numbers of individuals that have the traits useful for obtaining that resource. After a number of generations, the majority of the population will have those beneficial traits, and this is what we call evolution. Gradually, after hundreds of thousands or even millions of generations, one species will eventually produce another.
The concept of the “species” is obviously of central importance here, but how can we define species in such a way that we can distinguish one species from another if species are constantly changing? By far the most successful suggestion is what’s called the “Biological Species Concept,” given by this man: Ernst Mayr. In this picture, Mayr is standing in front of a walking whale skeleton; in any event, the whale walked, not its skeleton. Anyway, Mayr defined species as “groups of actually or potentially interbreeding populations which are reproductively isolated from other such groups.”
To give an example, let’s consider two humans. The lovely Ms. Natalie Portman and I are both members of the species Homo sapiens because there is the possibility that she and I might meet, fall madly in love, and produce viable offspring. I cling tightly to this hope every single day.
Some of you are laughing, and it’s probably because you’re thinking: “Yeah, not even if he was the last man on Earth!” That’s an interesting idea, actually, and it’s one worth considering. In fact, that idea—or at least a similar idea—is what initially led me down my research path.
So what would happen if Natalie and I were the last two remaining humans? What if we came across each other and her only thought was, “Oh, lord, no!”? What would that mean for our species? We’d go extinct, and it’d be her fault! Worse, what would happen if something were to happen to one of us? We’ll pick her, since she’s the reason we’re going extinct. What would happen if we were the only two Homo sapiens left and she were to disappear, leaving me as the last member of the species? Remember that a species is defined as a population; a population is sort of like a gang, and to quote one of my favorite shows—Flight of the Conchords—two is technically the smallest gang you can have. So the species Homo sapiens would be extinct, but I would still be alive! This is paradoxical: how can you have a living member of an extinct species?
Worse, what would happen when I die, that is, when nature selects against me? Suppose I run into some sort of apex predator. As a brief aside, for anyone who’s ever seen “Jurassic Park,” standing still when a giant meat-eating animal is standing right in front of you is a terrible idea. In any event, my death is clearly a problem for me as an individual, but is that what nature didn’t like? If I’m the last member of Homo sapiens, then we could just as easily say that there might have been something that nature didn’t like about the species. Furthermore, Homo sapiens the last remaining species in the genus Homo; maybe there’s something that nature doesn’t like about the genus. What is it that nature is selecting?
These two examples represent two of the primary problems in philosophy of biology: the species problem and the levels-of-selection problem. These problems plague philosophers and biologists alike and they have some important practical consequences.
Consider the species problem: how do we define species in such a way that we can draw clear boundaries between one species and another? On a related note, once we have a clearly-defined group, what is it that makes that group a species as opposed to a genus or a sub-species; how can we define the category?
Answering these questions has implications for ecology and preservation: consider the example of the red wolf. Some scientists say that the red wolf is a real species; others say that it’s merely a hybrid mix of gray wolves and domestic dogs. If it is a real species, then it’s endangered and we have to commit federal money to its preservation. If it’s just a hybrid, then it’s no big deal: we have gray wolves and we have domestic dogs, so we can make a new red wolf whenever we want.
Now consider the levels-of-selection problem: obviously, nature can select individual organisms, as we’ve seen. Those of you who have taken biology probably know that nature can also select individual genes. But can nature select whole species or, if not species, at least local groups?
The levels-of-selection problem means a lot to biologists, who can use the answer to this question in modeling how evolution and extinction work. Some scientists say that we’re in the middle of the greatest mass extinction since the one that killed off the dinosaurs, or at least the ones that couldn’t fly—birds are dinosaurs, after all. Understanding how extinction works is of obvious importance since if we’re in the middle of a new mass extinction then we certainly don’t want to be on the wrong side of any equations.
As I’ve said, these problems have plagued philosophers and biologists alike for a while. My suggestion is that a good way to resolve difficult problems is to take a look at how those problems developed historically: by understanding how a problem came to be, we might be in a better position to resolve the problem. So my goal is to look at the history of biology and to see how we’ve gotten ourselves into this position.
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