Essentialism and Evolution

I've been thinking a bit about Essentialism lately.  People seem to be wired up as Essentialists.  We love to, maybe even need to, classify things - that's a cat, this is a dog.  That over there is a tree.  Or is it a shrub?  And is that a Beagle or a Basset?  It's a hybrid?  What breeds?

Classifications and labels are very useful things, for sure.  Beagles are good hunting dogs.  Bassets... not so much.  Knowing which is which is pretty helpful when you've got a fox on the loose.

But it's easy to lose sight of the forest for the trees.  Richard Dawkins makes this point in his most recent book when talking about why some people seem to have a hard time grasping Evolutionary Theory.  Thinking of something as Essentially a dog appears to be a detriment when trying to understand how the species evolved and continues to evolve.

Take Beagles.  A "Beagle" is just a member of a population of beings similar enough to interbreed and produce something we'd still lump in with the Beagles.  Any one beagle is a member of that population, and will have characteristics that are within the normal range for that population.  That population is "All Current Beagles", lumped together based on our arbitrary description of the characteristics of the breed.  But within that group there is a lot of variation.  If you took the extremes of height from within the group - the tallest and shortest individual dogs - and stood them next to each other, it's less apparent that they're the same breed.

Now imagine splitting the population in two - half stay here, the other half are sent to Russia.  You breed them for 100 generations, selecting only the shortest.  The Russians do the same, taking only the tallest.

At the end, you bring them back together - the 100th generation tallest of the tall and shortest of the short would probably be considered different breeds by then - Great Beagles and Miniature Beagles, perhaps.

At no point along the way could you identify one individual in the group and say "your parent is a normal Beagle, and you're the first Great Beagle".  There's no clean line across the family tree - there's just a gradual shift from some individuals at the start that are clearly Beagle to an indistinct group in the middle to some individuals that are clearly Great Beagles at the other end(*).

Once we start thinking about things as individuals in a population, and the population as only roughly defined by a set of somewhat arbitrary characteristics, our view of things change.  No longer are there individual species... there's a massive population of living beings, some of which can interbreed and produce remarkably similar offspring.  Some very few of which can interbreed in fascinating hybrid ways.  And most of which can't interbreed.  Over many generations, the characteristics of the various populations will shift and morph to fit their environment, driven by the environment's relentless selection of only those individuals that are least-worst suited to it (IE: that can produce the most offspring).

Looking at it that way kinda makes the whole Evolution thing seem a little more clear.  At least, I find it so.


(*) - I picked height because it's generally a feature driven by many genes.  The case of dwarfism, though, would be an exception.  As I understand it, there is a single mutation that causes dwarfism in humans, and interestingly, I understand it's a very similar mutation that causes it in dogs.  Miniature breeds with short, stubby legs have that mutation, and it's quite conceivable that you could draw a line in the tree where that first shows up.  Aside from that, though, height is a good example for the point I'm trying to make.