Thursday, March 26, 2009

Intelligent Design and Evolution

Econospeakers may be interested in my mini-review of Michael Behe's effort to open the door to "Intelligent Design" in his book The Edge of Evolution: The Search for the Limits of Darwinism. (This was originally a letter to a friend.)

Reading Michael Behe's book, I came to the conclusion that even though he's a very clear writer and knows a lot (especially about malaria), it's no accident that none of the blurbs on the covers are from biologists. He doesn't know evolutionary theory very well. There's nothing wrong with chemists such as Behe "doing" doing biology (just as there's nothing wrong with economists such as myself doing it), but they should heed that profession's knowledge.

In his section "the importance of the pathway" (pp. 4-7) of the evolution of beasts and species over time, he wonders about the likelihood of a random process of mutation getting creatures from "biological point A to biological point B." If "you had to walk blindfolded from one side of an unfamiliar city to the top of a skyscraper on the other side -- across busy streets, bypassing hazards, through doorways -- you would have enormous trouble." He adds that this blindness would be "in the spirit of Darwinism, blind drunk."

I agree: there's little possibility of getting to the top of the skyscraper. It's very unlikely that a bunch of amoebae existing billions of years ago would take a random walk through Darwinian natural selection and end up typing these words into Econospeak.

The problem is that Behe looks at evolution backwards from the end result, implying that Darwinism is teleological, working toward a predetermined goal. Darwinism is not that way, as the late Steven J. Gould emphasized again and again. Just because many such as Herbert Spenser have tried to make Darwinism teleological does not make it so.

Behe assumes that creatures such as humans are currently on top of a skyscraper (with very complex organisms, etc.) and then asks how we could have gotten here blindly. But the exact nature of this point B was not predetermined; evolution is an historical, not a teleological, process. We might have ended up with completely different creatures, perhaps even with our planet lacking complex organisms. The amoebae may have evolved to write for Rush Limbaugh's site instead. Or for the Huffington Post. Or wherever -- or not at all. The current end-point wasn't known ahead of time.

It's more as if we stagger starting at one point in the unfamiliar city and we could end up anywhere. We might end up at the top of a skyscraper, but which skyscraper it was not predetermined. Once we get to the top of whatever building we end up, it make look like that was the only option, but it wasn't. History is contingent. It only looks like it was a predetermined process after the fact, just as winning a war seems inevitable only after you've won. Looking back at the process, the alternative paths that could have been taken are easy to forget because they did not actually happen.

After that, Behe misinterprets the randomness in Darwinian theory. It is not the randomness of flipping coins or of the blind drunk. Randomness in Darwinian theory refers to processes that are not explained by common descent or natural selection. (It's randomness relative to these.)

For example, we see that a parasite and its host can actually learn to live with each other, like a lot of the bacteria in our guts. Sometimes the parasite becomes part of the host, the way that organelles in our bodies' cells seem to have done. There's also the case where a large number of almost exactly the same kind of cell can form a "colony" (as with yeast), which turns out to give them all some adaptive advantage. Next, there's the principle of specialization: a hydra is a lot like a colony, but some cells specialize in doing some tasks, so that the entire creature can get an adaptive advantage. Then there are entire organs (such as our lungs) inside more complex bodies; each of these is like a colony which specializes in one or more of the body's function. Etc.

All of this is totally unexplained by selection, and therefore "random" relative to natural selection. But it is not random by other criteria. It is not a drunkard's walk.

On page 15, Behe seems amazed that the malaria microbes haven't figured out a way to get around sickle-cell anemia. But it's not like all types of germs have to be successful in the sense of killing off all of the people, etc. (There's no inherent imperative to kill people.) In fact, if the malaria microbe killed off all of the mammals it infects, it might kill the geese that laid the golden eggs for them: parasites that kill their hosts do not survive to propagate their species.

It's quite possible that malaria and sickle cells have reached a rough equilibrium where malaria continues to be reproduced generation after generation, along with its hosts, and the sickle cells have attained a similar status. It might be somewhat like the continuing relationship between predator and prey.

On page 16, Behe refers to E. coli as devolving: it's becoming simpler over time, so that nothing "of remotely similar elegance has been built." He assumes that one of Darwinism's ideological overlays -- i.e., that evolution produces more and more complex and elegant creatures as part of a unilinear "upward" path toward more and more "improvement" -- is part and parcel of Darwinism. But this is not true: point B might be a cheap motel rather than a skyscraper; it might be a cheaper motel than at point A. (As mentioned, the amoebae might have devolved to writing for Limbaugh.)

It's notable that this increasing complexity is not one of his three components of Darwinism that Behe defines at the beginning of his introductory chapter (mutation, selection, common descent). He sneaks it in after introducing those three pillars. In fact, it's quite possible that the increased complexity we see is only in the eye of the beholder: as Gould stressed, the dominant species on Earth are simple bacteria, not complex humans. We see complexity as so important because we're flattering ourselves.

Also on page 16, Behe wonders why malaria hasn't gone beyond the tropics. Again, what matters in the evolutionary process is survival to propagate, not expansion. It's not a matter of "survival of the fittest," which is often interpreted in terms of "better" species winning over others. Rather, it's survival of those species that are most able to pass their genes on to offspring that can pass them on to their offspring, ad infinitum. In order for this to happen, the species has to fit with its environment, but that does not mean that a species gets "better and better" or spreads to the entire world. It can be like those anaerobic bacteria that persist in volcanic vents. Isolated yes, but they survive for generations and generations. It's the latter that counts in evolution.

Though human beings have altered our ecological niche, the environment in which we live (especially once cultural evolution took over), that isn't true for all species. The expansion of malaria is blocked by other species which compete to use the same resources. We should not expect such a disease to spread all over.

I'm not an expert on malaria, so the details of my criticisms may be wrong. But I decided that it was not worth my while to continue to Behe's chapter 2. He has created his scare-crow figure of Darwin and has started the pre-determined process of knocking it down. In addition to advocating the use of "intelligent design" as an after-the-fact rationalization to fill gaps not yet explained by Darwinism, he has misrepresented the subject of his book.

I am not saying that Darwinian evolution does not have some holes. Rather, it is that trying to fill those holes by reference to intelligent design get us nowhere, adds nothing to our understanding. Standard biology is a much more useful tool.
Jim Devine


Econoclast said...

I'm adding a comment so that future comments will be e-mailed to me.

Anonymous said...

Analogies like the Blind Drunk are a way of downplaying selection in the evolutionary process when it is actually the dominant force.

As to complexity, if you plot number of species/specimens against their complexity you will get a big bulge to the left and a thin tail to the right. Given probability, the existence of a small proportion of complex species actually bolsters the case for evolution.

Shag from Brookline said...

Does ID theory suggest that at the beginning the ID was put in place and that everything that followed resulted from the original ID


that the ID continues, including with design changes from time to time to address bad origininal ID?

Econoclast said...

I am no expert on intelligent design. My guess is that it's opportunistic: wherever there's a hole in Darwinism, they try to stick God's Hand instead of doing research to find a natural explanation.

Shag from Brookline said...

" ... they try to stick God's Hand instead of doing research to find a natural explanation."

And they go back to the beginning, it seems, and come forward to the present, and continue into the future. Is there a sense of predestiny to ID, fate, kismet? Is it constant tinkering because of design flaws that need correction? And how are design corrections made? Like what may be the design correction for global warming? For diseases? For poverty? And the timing for such changes? Perhaps there is a committee that decides.

Jack said...

Describing Darwin's work as a teleological argument is the strawman of the natural design debate. Describe an explanation's antithesis incorrectly and then criticize your critics incorrectly, but to the naif it seems a sound argument.

As you point out, evolution is a process that moves forward with no plan, but as a result of a species' interaction with an environment. I like to think of the process as one by which the specific traits of an organism, or an entire species, may be conducive to that organism's better functioning within its environment. Those traits which may be more conducive to survival and recreation of that organism may be said to be inducive to that organism's continued existence on both an individual and species' basis. Nothing is deducive in this process. The theory doesn't suggest that organisms are faced with the task of accomplishment. It does suggest that those organisms which have advantageous traits are more lilkely to continue and may become increasingly prevalent in an environment.

John Morrison said...

The error Michael Behe makes has been dubbed the "Texas Sharpshooter Fallacy" in the Skeptic Dictionary. Someone shoots at a wall, then draws a bulls eye around the bullet hole.

He is only asking why outcome A occurred because outcome A just happened to occur. He thinks of the probability of A occurring, conditioned on A having occurred. In short, he is considering the conditional probability P(A|A) which is, of course, one.

Anonymous said...

To give another analogy to John Morisson's second paragraph, somebody does win the Powerball at least every few weeks even though that person's odds of winning were miniscule.