Wednesday, December 02, 2009

Dialectical materialism and evolution

If you understand biological evolution, you understand dialectical materialism.

Dialectical materialism appears to go all the way to the "bare metal" of reality: motion is a synthesis of quanta's dialectically opposed material properties of being "smeared in a wavefunction" and "observed as an eigenstate", but quantum mechanics is weird and obscure. Evolution is much more amenable to philosophical study.

The fundamental dialectic of evolution is the opposition of heritable variation and natural selection. Both of these dialectical elements are material: heritable variation is a physical, material, independently observable change in an organism's genotype, an eminently material substance (composed mostly of DNA). Natural selection is also a material process: physical properties of an organism's physical phenotype determine whether it will run faster or slower, have more or less acute vision and hearing, stronger or weaker teeth, etc. Furthermore, an individual organism's reproductive success is directly a material property: The organism has to physically reproduce to be reproductively successful.

Because heritable variation is uncorrelated with natural selection, these two elements are in true dialectical contradiction*. Heritable variation doesn't "care" whether it makes the organism more or less susceptible to adverse selection; selection doesn't "care" whether some heritable variation might be intrinsically good. (For example, it's intrinsically bad that human beings can't internally synthesize vitamin C — whether or not we can eat it, it would be better if we could synthesize it at need — but because our ancestors' diet was abundant in vitamin C, the loss of the ability wasn't selected against.)

*A dialectical contradiction is different from a logical contradiction. The use of the term "contradiction" is mostly historical — Marx's dialectic materialism springs from Hegel's dialectical idealism, where logical contradiction powered the synthesis, but also because while "contradiction" might be too strong the alternatives — conflict, opposition, etc. — seem too weak.
It's instructive to consider Mendelian (established at conception) vs. Lamarkian (acquired during life) variation. It happens to be the case that terrestrial organisms exhibit Mendelian variation, but we might have exhibited Lamarkian variation. If so, there would have to be something uncorrelated with natural selection about how an organism acquired traits for there to be a true dialectical contradiction between Lamarkian variation and natural selection. If this contradiction didn't exist, if an organism deterministically and predictably acquired just those traits that improved its survival, we would not see the pattern of complex, emergent behavior in the long-term development of species.

There are also important dialectical relationships in biological evolution at more abstract levels. A fundamental dialectic is between predator and prey. Again, the elements are material: the predator must physically catch and eat the prey, or the prey must physically escape the predator. And the elements are in true dialectical contradiction: the predator wants to eat the prey, the prey does not want to be eaten. Yet another is the parasite-host dialectic, which often results in symbiosis.

An important consequence of evolution is that it's neither predictable nor random. In my most important quibble with canonical communist terminology, I assert that dialectical relationships and historical factors do not determine the synthesis, they constrain it. There are specific features, for example, that would make predators ineffective: lack of speed, poor vision, poor quality weapons (such as teeth and claws); we will never see a predator with a predominance of features that poorly afford predation in its usual environment. We can predict to some extent where evolution won't go, but we cannot predict where evolution will go, even retrospectively. If we took a snapshot of any historical evolutionary epoch, we could not predict with confidence much of how the contemporaneous species would change.

Indeed the parallels between dialectical materialism and biological evolution are so strong that the following bold conjecture suggests itself: all dialectical material relationships are fundamentally evolutionary: they consist of a dialectical relationship between some form of heritable variation uncorrelated with some form natural selection.

3 comments:

  1. Very interesting post, dude. Here are a few clarifications:

    Because heritable variation is uncorrelated with natural selection, these two elements are in true dialectical contradiction*.

    This isn't 100% true. There are some biochemical mechanisms that implement heritable variation that are, themselves, subject to natural selection. This means that organisms can actually adapt via natural selection the nature and rate of heritable genetic variation to best suit environmental conditions.

    It's instructive to consider Mendelian (established at conception) vs. Lamarkian (acquired during life) variation. It happens to be the case that terrestrial organisms exhibit Mendelian variation, but we might have exhibited Lamarkian variation.

    Again this is not 100% correct. It is now well-established that there are so-called "epigenetic" mechanisms for the transmission of acquired variation from parents to offspring through the germ line (i.e., sperm and egg).

    The way this works is that during the life of the parent, certain environmental or physiological influences can alter the patterns of chemical modification of nucleotides in the DNA of the chromosomes, or of amino acids in the histone proteins of the chromosomes, in the sperm or eggs. These chemical modifications--mostly methylation and acetylation--are passed on to the progeny, can be copied as chromosomes replicate and cells divide, and influence gene expression in the progeny.

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  2. There are some biochemical mechanisms that implement heritable variation that are, themselves, subject to natural selection.

    You are of course correct in pointing out that the actual dialectical processes happen at multiple levels. But what I mean to say here is that each specific variation is uncorrelated to its outcome when the variation actually occurs. Even with higher level selection forces at work, no organism changes (or fails to change) its heritable variation because of the expected effect of that variation on the phenotype of the offspring.

    It is now well-established that there are so-called "epigenetic" mechanisms for the transmission of acquired variation from parents to offspring through the germ line (i.e., sperm and egg).

    Indeed. The wording should have been "... exhibit predominantly Mendelian variation..."

    However, it's instructive to consider that when epigenetically transmitted information is correlated with selection, it doesn't generate evolutionary novelty or nearly as much complex emergent behavior.

    Furthermore variation in epigenetic mechanisms is also uncorrelated with future selection.

    There are of course many features, characteristics and dynamic processes in biology that are directly correlated with selection. But those processes have evolved; they all rest on a fundamental "substrate" of dialectical materialism.

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  3. Is it fair to say that your overarching point about biological evolution is that the proximate substrates upon which natural selection acts possess no mechanism for altering themselves purposefully to promote desired heritable selective advantages? If so, you are surely correct.

    ReplyDelete

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