Saturday, January 28, 2006

So this is Life?

The Scientist features a story about recent advances in the field of abiogenesis, or the scientific study of the emergence of life from inorganic matter. Paul Meyers of pharyngula takes the position that "abiogenesis as the study of chemical evolution is a natural subset of evolutionary theory." My kneejerk reaction is to agree with the commenters who take exception to that view because it confuses or risks confusing very different concepts of evolution. I feel the term "evolutionary theory" should be reserved for the science that explains the origination of species of organisms by means of natural selection. The origin of life itself is another matter.

But it's not that tidy. Stochastic and epigenetic processes, in addition to adaption by natural selection, appear to have played a role in the evolution of lifeforms. These clearly belong under the rubric of "evolutionary theory." And some varities of phylogenetic systematics hold that natural selection acts upon whole phyla rather than simply species of organisms. Scientists working in these areas by no means reject the theory of evolution, i.e. the origination of species by means of natural selection. Far from it. But they do frequently argue against certain narrow views of evolutionary theory which can be misleading to other scientists as well as to the educated laity, students, or the general public. Thus in the broadest sense the claim that abiogenesis falls under the domain of evolutionary theory may be warranted.

Some commenters have raised questions as to the metaphysical implications of placing abiogenesis under the umbrella of evolutionary theory. I don't believe there are any. Not in the sense that's imagined here, of proving or disproving the existence of a supernatural Creator. The metaphysical implications that arise will be a matter of eisegesis, of reading into the history of life a priori metaphysical assumptions that empirical science is ill-equiped to either confirm or deny. A metaphysical reading of the history of life isn't necessarily dishonest or wrong--Fido the Yak is all about hermeneutic fun and games--but in this case it would seem to be clearly eisegetic. On the exegetic side, to be honest one needs to be aware of the difference between going in circles and revisiting one's assumptions in the process of learning something new.

There is a question here of whether empirical science in and of itself necessarily entails metaphysical claims. At this juncture I couldn't really say, but I can say that the phenomenon of susbstituting one's own metaphysical claims for the claims of one's field of study is rather all too common.

To return to the science of abiogenesis, "[m]any of the people approaching this are engineers, sharing in the philosophy that one can't truly understand what one can't build." Some also appear to be molecular biologists, chemists, astrophysicists, or interesting hybrids, like philospher Mark Badau, whose defense of "weak emergence" had previously captured my attention. Here, in no particular order, are the homepages of the other researchers quoted in the Scientist's feature:

If Badau is right about bottom-up approaches being more revealing than top-down approaches, then the classification of abiogenesis as a branch of evolutionary biology becomes a bit more problematical. Looking at Daemer's criteria for defining a synthetic protocell as life, it seems that Daemer views evolutionary growth as a stage prior to or apart from genetic encoding, mutation and replication. Indeed, much of the literature on evolvability or evolution in material substrates seems to be about chemical processes unregulated by genetically encoded protiens, and not invovling biological reproduction as we know it. However, the theory of natural selection is being used by some researchers to generate models of abiogenic evolution. In this case I think it's too early to say that such uses of natural selection qualify the emerging field of abiogenesis as a branch of evolutionary biology.

posted by Fido the Yak at 8:17 AM.


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