23 may. 2011

Common Descent

The easiest concept in evolution to grasp is common descent. If you take a bunch of varieties of oak trees, you can figure out that there was a common ancestor to all these varieties. And of all trees further back. You can see that a cat is related to a tiger and a lion. There is a kinship there. You can also see lesser degrees of relation among more distantly related creatures, birds and mammals, say. So the classification of animals and plants into hierarchical categories already implies this relatedness. To me this is more intuitive than other concepts in evolution, and more self-evident. We see a similar kind of branching effect in language. Italian and Spanish obviously are different languages but they share a common ancestor. Or styles of rock music. It is obvious that they evolved from common roots, that they bear similarities and relationships through common origins rather than from some individual act of creating various styles all at the same time. Biological life, too, looks more like a thing that developed through a series of changes like that, than like something designed consciously all at once. Evolution had to be invented, by Darwin or someone else, once there was enough knowledge of biology, simply because of the intuitive principle of kinship. You can tell one kind of cow is related to another variety of cow, but less related to a horse. Not even the stupidest creationists try to go against common descent overtly, because it is just too powerful.

Once you admit common descent, though, isn't the rest of evolution just inevitable? All you need after that is a mechanism of change and differentiation, mutability and selection, and a long enough time-scale for it to occur. I'd like to reason this out for myself in entirely layman's terms, since i'm not a scientist of any sort. I actually think it's more important that I understand it than for someone who already knows this kind of thing professionally. A shocking number of Americans don't accept evolution at all, so in this case a simplistic understanding is better than a sophisticated one.

14 comentarios:

Vance Maverick dijo...

Indeed. Have you read any of the pop-science literature on this? Dawkins is pretty good (the older Dawkins of The Blind Watchmaker and further back, perhaps not the atheist polemicist). He wouldn't disagree with your claim that the idea is easy.

Darwin is also good, of course. Try the first edition of the Origin -- pitched at the intelligent amateur, and awesomely well-organized.

Jonathan dijo...

I've read parts of "Why Evolution is True." By Jerry Coyne.

Thomas dijo...

I also take the lay-approach to this. But I've got to say that I'm as annoyed with stupid evolutionists as I am with stupid creationists. There is plenty of room for dogmatism in both accounts. And lots of space for the excercise of real intelligence.

Dawkins is being stupid in the Selfish Gene (and insistently so in the footnotes to his later editions) when says that all attempts to answer the question "What is man?" before Darwin showed us "the truth" in 1857 are "just plain wrong". Which means Dante, Pascal, Shakespeare and Kierkegaard simply didn't know what they were talking about. Or when E.O. Wilson stupidly says that Kant's philosophy is a failed attempt to model the brain and we should scuttle the hulls of most of what we thought about our origins and leave them burning on the shore (or some such adventurous imagery). It's just dumb, simple-minded, brutishness. And then, on top of it all, it's meanspirited.

There are people who believe we were "seeded" by an ancient alien civilization who are much more interesting to talk to about what sort of beings humans are than people who have just let Dawkins or Hitchens convince them that "creation" is a crock, a hoax, a sham, an error, a delusion, whatever. They just like the way their voice rings with conviction when they say it. It's stupid.

Jonathan dijo...

I don't really think there is any equivalence. Dawkins has some silly ideas, and I can't stand Wilson, but at least they know that evolution happened. They are just drawing mistaken conclusions.

Vance Maverick dijo...

I'll admit that Bad Dawkins is visible even in the older books. But he also satisfyingly articulates the beautiful positive ideas from Darwin. And is Dawkins for the prosecution really less irritating than Eagleton for the defense?

Jonathan dijo...

Eagleton's answer to Dawkins is more insufferable than Dawkins could ever be. For example, "Those who don’t see this dreadful image of a mutilated innocent as the truth of history are likely to be devotees of that bright-eyed superstition known as infinite human progress."

Huh? We are trapped between providentialist Christian eschatology and a caricature of 19th century progressivism, without any other alternative? Are those the only two theories of history out there?

Clarissa dijo...

In his new book - as bad as it is - Eagleton at least dropped his annoying insistence that progress is a useless term. Maybe somebody pointed out to him that saying no progress ever happened is sexist, racist and homophobic. Besides, since we are all moving towards the bright Communist future, that is definitely progress.

Vance Maverick dijo...

I see I got the sign switched -- I meant, "is D really more irritating than E?", to imply that E, indeed, is worse. He just refuses to take a clear stand on the obvious issues, like what versions of religion are relevant to the discussion.

Jonathan dijo...

Curiously, I understood what you meant anyway. My brain has a problem with overnegation so I just assumed you meant what you really did rather than parsing what you actually said. Eagleton is 10 times worse, I agree.

Thomas dijo...

I don't think it's a contest between Dawkins and Eagleton, and certainly not a question of who is more irritating, or who is more entitled to irritate whom. I have yet to learn something about evolution that undermines my belief *in the possibility* that it is part of some great design (whether alien or divine), and I really find the rushed attempt to cash the theory out as a theology (atheism is an account of God) boring.

There is too much beauty in the world to rule out the possibility of design. But there is too much evil in it, too, to believe straighforwardly in a divine plan. I certainly know enough about Dawkins's mind (his style of thinking as revealled in his rhetoric) to know that I'm not going to ground my image of God in the sorts of things he knows, though I don't doubt that he knows them. (Like the rest of you, I think he does a great job of describing, e.g., how replicators account for the emergence of complexity.)

If we're not going to let biology explain away literature then I don't see why we would let it explain away religion. Literary experiences are undeniable. So are are religious ones. The question is: what do they mean? I'm not leaving it to biology (or any science) to figure it out.

Vance Maverick dijo...

In the spirit of comity, a list of the top ten species described in 2010. Marvelous however you interpret them.

Jonathan dijo...

That's great. I was looking at that yesterday. I don't find the atheist view of nature as any less awe-inspiring, In other words, I don't find anything added to my sense of awe if I posit a creator or designer. Nevertheless, I recognize many people require (what I see) as this extraneous step, just as they do in other areas.

Thomas dijo...

Borges: "Did Dante want us to think that Ugolino ate the flesh of his children? I would hazard a guess: Dante didn’t want us to think so, but he wanted us to suspect it. Uncertainty was part of his plan.” With the same uncertainty, some prefer to suspect they were created by an intelligence. They don't "posit" a creator. They merely acknowledge the possibility.

Vance Maverick dijo...

If you want us to acknowledge that the Dawkinses of the world are unreasonable in thinking science preëmpts religion, Thomas, do consider it acknowledged. I don't really want to argue religion directly, though....