Evolution and Dawkins

I’ll be working on Chinese for this upcoming week soon, but thought that I should go ahead and empty my brain a bit. I have been reading the Dawkins books that I recently ordered from and have been needing to read for some time. The Blind Watchmaker was finished a few days ago, and I just started Ancestor’s Tale. Dawkins is a wonderful writer, and is great at explaining difficult scientific concepts (which probably explains why he is a Science Education for the Public professor at Oxford or wherever he teaches).

I wasn’t quite sure what to expect from Dawkins, as I often hear of him being quite callous and angry towards creationists and the like. Though the callous response is quite deserved, I haven’t seen much of it in these two books. Though I love a good ignoramus-bashing, it gets tiresome, especially with all of the militant atheists on the Internets that use evolution as a tool for combat. It gets old quick, and I think is a bit counter-productive since those who “don’t believe in” evolution (as if it’s a matter of belief) aren’t actually capable of understanding the concepts involved.

So far, every time that I have learned something new about evolution, I find it even more amazing and beautiful of a, for lack of a better word, force (though it most certainly is not a force in any real sense).

In Ancestor’s Tale, Dawkins is tracing evolution backwards to the origin of all life. He has it set up so that we meet each of our fellow evolutionary “travelers” at the most recent common ancestor and then, joining them, proceed to meet the next.

The first thing that I was struck by was the discussion on the Homo line, from 6 million years ago to us (sapiens). Though I had heard that Cro Magnon and Neanderthals lived at the same time, I had not actually sat down to think about this. Indeed, it appears that at many points in the recent evolution of our species there were multiple species that could have been our ancestors, and all of them lived at the same time and possibly the same place! Of course, I immediately think of The Lord of the Rings, where humans and elves live together side-by-side. Imagine, two different species of modern man living simultaneously (though I guess they might have been capable of interbreeding, so were not technically different species), either of which could have led to intelligent organisms like us. If the Neandterthal line had not gone extinct, we might be living in a world with another race of intelligent people that we could talk to! Of course, chances are one of them would enslave and abuse the other; such is the tendency of our stupid genus.

The other thing that struck me was the image that Dawkins’ tale brings to my mind. He doesn’t put it forth in the same metaphor, but my brain created a rather beautiful picture of the journey back in time.

The image is this: Picture a massive tree, its thick trunk splitting into a few slightly thinner branches, and those new branches doing the same again, on and on until the massive trunk has turned into millions of tiny twigs, miles and miles into the sky. The height from the ground represents time, so that the very top of the tree is now and the very base is the dawn of evolutionary time and therefore the location of the ancestor to every other living thing on our planet. The tips of every branch and twig, except those on the top, are points where a species has gone extinct. Every species that has ever gone extinct has a representative member sitting at the tip of its extinction twig. Imagine all of them sitting there, on their respective twig tips, absolutely immobile. Now, the branch tips at the top of the tree are the locations of every currently surviving species, and each again has a representative perched there, immobile. Each branching point is the location of a common ancestor, so that two species moving down their respective twigs, and thus backwards in time, will meet at the point where they are no longer different organisms. They will have become their ancestor.

This is a lot of set up for this visual, but I think it is worth it. Remember that distance from the ground represents time, so that climbing the tree is going forward in time and descending is going backwards. Now, here we go:

The creatures at the very top of the tree have stopped being immobile, and suddenly start climbing downward along their twigs, all at the same rate (in time). As they descend, their features steadily change as they move backwards in evolutionary history and their DNA changes. We see a chimp walking down his twig, and on the twig right next to him a bonobo. Both are walking at the same pace, and we see that they are becoming more and more similar to one another. As they approach the place where their two twigs have branched from one, they are essentially indistinguishable. They collide at the branch point, becoming one organism- the most recent common ancestor of the bonobo and chimpanzee.

This new creature does not stop, however, but keeps moving down the tree. We suddenly notice that the branch that the human was climbing down is now occupied by something that looks human, but is also strangely chimp-like. As the chimp-bonobo ancestor marches in pace with the human ancestor, we again see that they are morphing into something more and more similar. Then, at another branch point, they collide. Bonobos, chimpanzees, and humans are now one creature, and that creature keeps plodding along, eventually meeting the rest of the apes, then monkeys. Eventually all mammals, even those that have been extinct for millions of years, have coalesced into the single descendant of all mammals.

Zooming out from this unfairly limited perspective, we see that the entire tree is one moving mass of creatures, all moving towards the ground. As the organisms reach a time in the past, those that went extinct at that time begin to move as well. The creatures continue descending, coalescing, and becoming fewer and fewer in number, until all things that ever lived have coalesced into a single thing. Of course, that single thing could be a bacterium, or simply a piece of RNA.

This picture of life really brings our kinship with other organisms into focus, and I think that is important. Of course, I left out visual representation of plants and many other things, simply because it is much more difficult to picture a tree walking down a tree…

I really think that evolution is beautiful, and anyone who chooses to pretend that it doesn’t exist is really missing something amazing about the world. [Note: Another good introduction to the topic, written for a non-sciency audience, is The Making of the Fittest, by Sean Carroll. I’m using this for a class that I am a teaching assistant for.]

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