The Inevitability of Evolution (Part III)

THE THIRD FALLACY in this series (after Part I and Part II) is failure to appreciate the nature of biology Biology isn’t coin tossing, card shuffling, or English history. It’s based on organic chemistry, and it has its own rules.

Let us illustrate those rules by returning to the card-shuffling analogy, but playing the game according to the way evolution actually works. Suppose we were in a gigantic casino, observing the players at a million tables simultaneously. There are trillions of tables where games are going on, but we’ll just watch this group. A million is enough for our purposes. (Meanwhile, the creationists are watching only one player as they grumble about “the odds,” but they don’t understand how the game is played. The creationists are looking for one long improbable serial sequence, while we’re watching a large number of parallel events, one step at a time.)

We’ll use a deck of cards as a simplified metaphor for a sequence of genetic mutations that the creationists are claiming is impossible. We want to see if that sequence can emerge without supernatural intervention. For convenience, let’s define that sequence as the original order of the cards, and let’s see if evolution can get there after a good shuffle of the deck.

Remember, we’re not playing Intelligent Designer, deliberately intervening to achieve a desired result in the future. We’re playing detective, trying to look back so we can see how an already existing result could have been achieved by natural means. In doing so, we won’t behave like creationists by figuring the odds against us and then throwing up our hands and saying “It’s impossible!” We’re looking for a way these things may have happened.

Remember also that even if we find a way, it may not be the way it actually did happen (we may never know that); but if we can find a natural method for accomplishing the allegedly impossible sequence, then we’ve demolished the foundation that supports the edifice erected by the “It’s impossible!” crowd. They won’t admit defeat, of course. They never do. Instead they’ll demand of us what they never demand of themselves; they’ll want absolute proof that what we’ve described is the specific way the sequence really did happen, and if we can’t do that (which we can’t) they’ll huff and puff that we’ve merely concocted a “just so” story. They’ll completely fail to grasp that if we’ve shown one possible method, then … well, it isn’t impossible after all.

Before playing, let’s be sure to avoid the first two fallacies we’ve described earlier in this series of essays. You remember the odds against dealing a specific sequence of 52 cards, don’t you? The chance of achieving such an outcome is only one in 8.06581752 times 10⁶⁷. That doesn’t bother us because we’re not the Intelligent Designer, intentionally intervening to achieve the entire sequence. We don’t need to collapse the continuum; we’re just going to take it one card at a time. Also, we know about the scale of things, so we’ll take advantage of the large number of players and the long span of time available to us.

Now we’re ready to start. The game at each table is to deal out a shuffled deck, one card at a time, and end up with the cards in their original sequence. Ah, I see that you’re worried; you fear that it’s nearly impossible to win this game. Normally, it would be; but don’t be confused by the deck of cards analogy. This isn’t a normal game! Remember the fallacy under discussion — failure to appreciate the nature of biology. Be of good cheer, because by using evolutionary algorithms, the game works like this, at each of the million tables we’re watching:

1. Each table has a differently-shuffled deck. Each card dealt is a mutation that appears in an act of reproduction. Mutations are common, but they happen randomly from our point of view. They’re quite natural, however, because they follow the rules of organic chemistry. A card may appear in the next generation or we may have to wait a few generations. It doesn’t matter. We have time.

2. Only players at those tables where the first card dealt is an ace of spades will remain in our game. The others vanish. They don’t necessarily die (many mutations are harmless), but we’re no longer interested in them. For our purposes they’ve lost the game, and we’ll let them drift away into the biosphere. The losers may still be lurking around and playing a different game of their own, but we’ve dismissed them from million tables we’re watching. Note that although we’re being selective about the players we observe, we’re not actually interfering with them.

3. The players with an ace of spades then reproduce — this is biology, remember? — and we’re soon back to a million tables with players in our game. Unlike the creationists, we’re not watching only one creature and waiting an arbitrarily short time for it to develop something complicated, so that when it doesn’t (which is likely) we can foolishly claim that we’ve disproved the theory of evolution. Life doesn’t work like that except in creationist literature.

4. The next round begins with dealing card number two. At every table we’re watching, all the players are now “ahead of the game,” because they’ve already drawn the ace of spades. By the way, because we’re watching an existing feature develop, we know that the sequence we’re observing wasn’t fatal to those who have it, so we don’t need to worry that these mutations will injure those who get them.

5. The same rules apply for getting the two of spades. Those players that do it survive and multiply. The others drift away from the tables, and will be replaced by reproducing “ace-deuce” players. Bear in mind that not every “ace-deuce” player will stay in the game. Some may draw a card that proves fatal to survival, and some may fail to survive and breed for other reasons. These things happen. If players die, they’ll be replaced. That’s how it is in this game. It’s all a matter of numbers, reproduction, time, and death. But enough players should survive — and reproduce — that we’ll always have a million in the game.

6. Repeat for the three of spades. Then again for the next card. Keep going. Some players may never get beyond the first mutation or two. That’s okay. We have enough players that one of them should eventually get the next card, and when that happens it will reproduce and fill the other tables with its progeny. The game will never lack for players, and each round is just like the first — some player will draw the right card, and soon we’re back to a million players again. If we’ve already been through five or six cards, every one of the million players now has those cards because they’re the descendants of prior winners.

7. By now you can see how this is going to end. If not, go back and read through the steps of the game again. Eventually we will end up with one table where the cards are all dealt in sequence. It probably took a long time, and we went through a great number of players that didn’t draw the right card at the right time. When we finally get one player with the right sequence, it will reproduce, and before long we’ll have a million of them. Maybe more. Game over.

What did we learn from this? Several things:

The sequence of mutations needed for significant changes doesn’t happen simultaneously. It’s step by step, and each step is entirely possible because it involves reproduction and mutation on a massive scale. Evolution works with large numbers. No miracles, just a long chain of natural events.

The initial winner is a distant descendant of the first player that drew an ace of spades, perhaps millions of years earlier. From that long ago first card to the last, the odds against any one of the billions in this generation being the winner were indeed immense, but considering the rules of the game, it shouldn’t surprise us at all that there has been a winner. (If the lottery worked this way, you could keep an old ticket that had one correct number out of six, and then continue playing that ticket in future lotteries until you got a second correct number — the first number would always be good — and so on until you finally got six winning numbers. Nice game.)

Although we might be tempted to marvel at the winner’s “luck,” we should remember that there were probably trillions of others in related lines of descent that were dropped from the game because they didn’t inherit the string of mutations that this one did. It’s not luck, it’s statistics.

What becomes of the losers and their descendants? There are trillions of them. Some lines became extinct, but others are probably flourishing. Their own sequence of cards reveals that they’re related to the winners, and it can be shown exactly at what point they dropped out of our game. There’s nothing wrong with them, but they’re not the same as the players we’re watching. They’ll go their own way, perhaps mutating in some different direction. It’s a big world with room for lots of variation. Hey, that’s why there are still monkeys!

Amazingly simple, isn’t it? Evolution bypasses the odds. A successful mutation needs only to occur once, out of trillions of opportunities. Then it will rapidly multiply. Losing events are discarded. The same odds apply to the next successful mutation, and so on. Did you get that? The “odds calculator” is reset with each round, and every generation is the start of what is virtually a new game.

Winners not only remain in the game, but they reproduce, so that in the next round their descendants have already won the prior round — and all the rounds that went before. Each new round is played only by winners, and they’re always producing more winners to replace those who lose. How do the odds look now?

So that’s the third fallacy — failure to appreciate the nature of biology. All creationists’ arguments that involve this fallacy are worthless. Evolution works. You can bet on it.

[See also: Behe Rejects Evolution by the Numbers.]

Copyright © 2009. The Sensuous Curmudgeon. All rights reserved.

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