Sunday, August 13, 2006

More ramblings on evolution, extinction, etc

I’ve been reading about life recently, by which I mean living things (as opposed to life as human existence). I find the grand synthesis type books very interesting, trying to bring a variety of disciplines together. James Lovelock’s books are interesting from this point of view. Gaia theory seeks to explain how the Earth, with its atmosphere and oceans are and remain conducive to the existence of life. Homeostasis is the process whereby the temperature of the Earth has remained more or less constant (notwithstanding ice ages and warm periods) as the Sun has increased in brightness. Lovelock can sound rather pompous and triumphant at times, as much of his theory has been vindicated.

One of his collaborators has been Lynn Margulis. She is responsible for another grand synthesis theory, this time for the evolution of life. It is described in the book The Symbiotic Planet: A New Look at Evolution. She exhibits much of the same hubris and arrogance. He idea is that life has evolved as new symbiotic relationships have been struck up. Serial endosymbiosis theory (SET) claims that bacteria merged in the distant past to form parts of the modern cell. For example, Margulis demonstrates that there are chromosomes outside of the nucleus of prokaryotic life (life that has cells with a nucleus as opposed to eukaryotes like bacteria that have no nucleus). For example, the mitochondria that burn oxygen in our cells as said to have started life as free floating bacteria. Mitochondria have their own DNA that is passed down from the mother’s side, which has allowed scientists to find the seven out of Africa “Eves” (I forget the title of the book). There are four stages to the model, and the only one that remains controversial (part of so called extreme SET) is that, for example, the tails of spermatozoa started as free wriggling spirochetes.

Margulis would then content that we are all walking colonies of bacteria (indeed, our guts are full of bacteria, both helpful and harmful to us). One of the things that Margulis concludes is a typically materialist one, which reduces humans to a product of the random process of evolution. It is hubris to see ourselves as “a little lower than the angels”. She sees Gaia (as Lovelock does) as being able to get on fine without our interference. Gaia can’t be harmed by us and that we are arrogant if we think that we can be stewards of her. Although she would probably prefer the expression Gaia not be used since it has attracted new age thinkers and the idea of mother Earth, she too sees use in the metaphor so long as personification and teleology are excluded.

A few reflections from a Judaeo-Christian perspective are warranted. I think there is a lot to be said for reducing the hubris of humanity and thinking that the natural world (creation) revolves around us. The Genesis narrative is theocentric (God centred) not anthropocentric (human centred). Having said that, the Psalm that Margulis despises is misunderstood by her. The Psalmist points out that human beings ARE insignificant when viewed alongside all of God’s creation. Yet, he HAS chosen us to be a little lower than the angels. It is of God’s choosing, not humanities superiority. We differ from our fellow creatures quantity, since we have more of everything (brain size, cognitive ability, see Rogers’ Minds of Their Own), etc. Animals are not automata (well, some of them at least, see Raimond Gaita’s The Philosopher’s Dog). I know my dog is aware of a lot of things.

Yet, animals are not human even if humans are animals. Further, there is a manner in which humans are a danger to parts of Gaia even if not to the whole (yes, cockroaches will rule the Earth if we irradiate it). It is not only in our own interests to look after Gaia (although it is very much in our own interests not to poison water, air, soil). Given that some ecosystems are isolated and unique, every tropical hillside is potentially something unique that can be lost. As David Raup notes in Extinction: Bad Genes or Bad Luck?, we are conscious of what we do – the only conscious agent of extinction on the planet (though see below).

Further, Margulis is right to elevate the importance of bacteria. They are essential to life, having helped make this planet habitable in the past (producing methane to keep the Earth warm when the sun was dimmer, produced the first oxygen that allowed all “higher” life to appear) and now. Likewise, she rightly rails against certain aspects of the warfare model of humans and bacteria. However, like Lovelock, she is somewhat insensitive to human suffering. We suffer the effects of bacteria; pain of their inhabiting us and pain of loss when our loved ones die. Yes, we create monsters with use of too many drugs. However, what if we did absolutely nothing? Margulis follows the reductionism of her trade too far.

But back to Raup. Margulis provides a novel approach to the origin of new species. Some Christians will dislike this since they dislike evolution altogether. New species should not arise unless God explicitly intervenes to make them so. However, I’d contend that this is not the “problem” of evolution. Raup’s book (and also Margulis when discussing the origins of sex) claims that death is part of life. Mass extinctions are a combination of bad luck (comets, large eruptions) and bad genes (some extinction events are selective – like megafaunal losses when human beings arrive on new continents). He prefers the term, mass killings, since that is what they are. If a genus contains only a small number of species, then that species may die out more easily. Likewise if a species contains only a small number of individuals, with one or two populations (this has been a real problem with the conservation of endangered species like the Kakapo, a flightless parrot in New Zealand), that species is very vulnerable to extinction.

When one looks at the distribution of numbers of species per genus, it is a power law distribution (or a log normal?), with most having few species. Likewise, with extinction events, it is the same distribution. This suggests that there is nothing special about big events other than they occur far less often. Death is part of life. 99.9% of all species that have ever been alive are extinct. Therefore, the problem for the Christian should not be the origin of new species, but the profligacy with which evolution produces death. Where are the theologians of extinction?

If God is the sovereign God who determines all things in every particular (meticulous sovereignty), then he pre-ordains so much death. True, out of the ashes of old species come new, by either producing new species from the old, or allowing the production of new evolutionary niches as they are vacated. Nonetheless, there is a lot of blood on his “hands”. If creation is given the freedom to develop itself, then God only creates the possibility of death. Mind bending stuff.

However, I can’t follow Margulis or Lovelock into materialism. Jesus shows us the God who suffers and dies along with creation. How the details of a theology of extinction work out, I don’t know at this stage, but it is this, rather than the origin of species that troubles me.

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