Thursday, July 23, 2009

Darwin Bicentenary Part 25: Challenging a Spinful View of Evolution

In a relatively obvious sense the universe has direction; the laws of physics, along with the boundary condition imposed on the universe, are such that the cosmos is in thermodynamic disequilibrium. This results in the well known temporal directionality which means that the time line does not look the same in both directions. It is also clear that there is a biological arrow of time; there is a kind of morphological disequilibrium in that an increasing fraction of cosmic matter, on Earth at least, has slowly become locked up in organized (and complex) biological structures. Morphological disequilibrium may, in fact, be an aspect of thermodynamic disequilibrium as I will shortly suggest.

One thing is very clear: In terms of what is absolutely possible the organized complexity of living structures are highly unrepresentative configurations. Something, therefore, has considerably enhanced the chances of living structures coming about, and if this enhancement is not down to the direct action of design by intelligence (as postulated by the ID theorists) then the only other alternative currently on the agenda is that the probability of life has been considerably raised by the appropriate physical package of laws and boundary conditions, a package that must severely restrict the degrees of freedom available to matter.

If we imagine a system where probability was evenly spread over every conceivable possibility, then probability would permeate the space of possibility as an extremely thin “vapor”. Because the class of living structures has such a low statistical weight, then under these conditions there would be no realistic chance of life making an appearance. However, if evolution has occurred then the cosmic physical regime must so constrain what is possible that it forces this very thin vapour to “condense” into a fibrous network of very thin fibrils, fibrils in which are embedded the structures of life. Moreover, these structures must have sufficient near neighbor relations within the strands of the fiber to allow evolutionary diffusion to migrate from structure to structure in a quasi continuous way. It is important to understand that this conjectured fibrous network doesn’t exist in any tangible sense but only in a platonic mathematical sense in as much as it is an abstract structure implicit in the laws of physics. It would classify as a kind of chaotic complexity arising out of mathematically simple laws.

If this fibrous network has a mathematical and real existence it means that evolution is, ironically, an outcome of the second law of thermodynamics. This follows because thermodynamic disequilibrium ensures that matter, gas like, strives to fill the volume of possible states open to it; if that volume includes the states of life as a significantly large fraction of what is possible then diffusing matter will very likely find those states. But, and this is the big but, this dynamic only has a realistic chance of generating the highly unrepresentative structures of life if the physical regime has considerably suppressed the overwhelming number of non-life configurations, leaving an abstract fibril network that severely limits what states matter can visit.

As an aside, here, let me acknowledge that the ID theorists have a right to challenge the mathematical and evidential basis for this conjectured morphological network of fibers. As far as I am concerned the ID community’s challenge may be valid and that is why I’m carefully scrutinizing their work. However, if evolution has occurred in the way currently understood then the morphological platonic fibril structure is a necessary condition of evolution.

However, proceeding under the assumption that evolution has occurred, then it is clear that the morphological network effectively gives evolutionary diffusion direction in as much as there are preferred directions of development, directions weighted by the underlying physical laws. It’s a bit like a hand powered railroad car operated by a drunk unsure in which direction to move, east or west. Although there may be no preference by the drunk driver whether to move east or west, there is clearly a directionality here determined by the railway track. Of all the directions in which movement can proceed the railway restricts motion only to an east-west directionality. In a similar sense evolution certainly has directionality; the laws of physics must provide a limited set of directions in which random change can proceed, otherwise there will be no chance of evolution.

The foregoing preamble was necessary in order to comment on this post by Larry Moran where he posts a video discussion between Robert Wright and Daniel Dennet on the subject of direction and purpose in evolution. Larry says:

Watch Robert Wright and Daniel Dennet discuss direction and purpose in evolution.

Now imagine what the discussion would look like if they really understood the important role of chance and accident in evolution and, instead of humans, they used lobsters, ginkgo trees, shiitake mushrooms, rotifers, and cyanobacteria as examples of modern evolved species with three billion years worth of ancestors.

Even worse, think about the octopus. Is there any sane person who would point to the existence of those eight-legged slimeballs as evidence that evolution must have a direction and a purpose?

The directionless and purposeless of evolution is one of Larry’s big themes. However, his continual emphasis on the important role of chance and accident in evolution entirely misses the point. Chance and accident only have an effective role in evolution given the sort of highly organized fibril structure I have been talking about. This structure, if it exists, must be implicit in the laws of physics and so limit the degrees of freedom of matter that evolution attains a realistic probability. In and of themselves chance and accident are useless and to over sell the role of chance and accident is to put an entirely wrong spin on evolution. This spin is a distraction from the remarkable fact that if evolution as we know it is to work then a very constrained directionality must be imposed by the physical regime.

At first sight a dithering drunk operating a hand powered rail car may seem to be directionless, but when we become aware of the outer frame which includes the very limited degrees of freedom imposed by the track then it is clear that directionality is the name of the game. For reasons of his own Larry Moran finds it difficult to give cognizance to the outer frame of laws and boundary conditions which impose directionality on the universe. On the question of whether evolution has purpose I will not comment here, neither will I comment on whether or not the complex pathways of a network of “rail tracks” of evolutionary development can be encoded in few lines of physical equations. But one thing is clear; evolution requires matter to have such limited degrees of freedom that directionality effectively exists.

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