Into the Wardrobe

Richard Lenski scores!

44,000 generations. Six per day, 365 days per year, 20 years. I recreated an experiment like this once, just for 70 generations to see if I could pick up the effect of natural selection. I barely got it. Selection effects dominate for about 1000 generations, when you are basically killing off any bacteria that don't have the right genes to do well under pressure.

Lenski just has the bacteria dealing with their own overpopulation. After a few hours (about 6 generations) the bacteria have reached the carrying capacity of their environment and are starving for the rest of the day, until you take 1 percent out and put them into a brand new beaker with food. I actually added a specific stressor: salinity, and tested for ability to grow in salinity. Lenski is measuring all kinds of changes.

For the next few thousand generations, bacteria change more slowly because of recombination producing more beneficial gene complexes.

Here, at 44,000, they got their first paradigm shift, the creation of a new gene complex. To do this requires multiple steps, which is what they want to go back and look at by analyzing the frozen generations. It's not a "slot machine" where they just got lucky to get the right combinations of genes. There will be a set of intermediate states and a pathway between them - exactly the kind of thing that some (but not all) ID theorists say is impossible.

This experiment involved twelve discrete populations over 20 years. Natural bacteria work in a partly continuous world. Hypotherically, all water bodies are connected so the bacteria are in one "beaker" but because of time of travel constraints, they are not a single population. We're probavly talking about thousands to millions of times the repetitions of Lenski's experiment in space and a hundred million times in time, in order to get the breakthrough of something like photoreceptors. There may be a billion steps, too, a billion useful intermediate forms between rock chewing basic biochemistry and light sensitivity.

This has been one of the most important ongoing experiments, but by itself it certainly does not close any cases. However, it may eke out some general information on the transition of a genome through intermediate states to some important consequence, which may ultimately allow us to estimate the time required for certain changes without resorting to "hand-waving".

Interesting read. Excuse my lack knowledge on the subject but what is keeping this trait from being a long held recessive trait that has just not been seen till now?


Paraphrasing Eustace: "Oh I thought stars were giant balls of gas floating out in space"

"That is what they are made of, but not what they are."

Hi Russ

Perhaps we are more in agreement than I thought. Like you I see a philosophical problem here but my problem is not with evolutionary theory as such but with materialism. By materialism I mean the kind of worldview that sees matter/energy in some form as being the only final reality and sees all other kinds of laws and properties as being in some sense derivative. In that kind of view evolution becomes not only a biological theory but a theory of everything. Now I think it is interesting to poke around looking for evolutionary explanations for aspects of human psychology but this may also miss some vital truths.

I got into an interesting conversation about this kind of thing with a friend who had studied biology and done a lot of human dissection. He was talking about the discomfort people feel in the presence of a dissected corpse. He asked me whether I thought we would have such a taboo other than for religious reasons. I said surely yes because animals react with fear in the presence of violent death. That must I said be part of their evolutionary programming. Yes, he responded, it would be a warning there is danger about, a flight instinct.

So evolution can go a long way to explaining the taboos human beings feel in the presence of a corpse. We can see why such an instinct would have a survival value. We can only guess how that survival value became entangled with religious ideas about death. But I think we can say that these taboos were stronger in paganism than Christianity. I think Lewis really speaks as a pagan rather than a Christian when he sees overcoming this taboo in order to dissect a body as a bad or dangerous thing. It was under the influence of Christianity that people escaped this largely pagan taboo and medical science was able to advance (an account of this is given in Starkey's 'For the Glory of God')

But I think there are some aspects of death that can only be explained in religious terms, and so I will grant some validity to Lewis's reservations about dissection. For if we begin to think of life only as a more or less accidental property of matter, then there is a danger that we somehow lose the sense of a person as a person, and I think the abiding Christian sense of death as something wrong or abnormal is a true insight. This is not just an organism that has ceased to function, it is a person who has been lost to us. I'm thinking with my pen here, a good time to stop I think.