Essential Character of Non-Life Evolution
I found the class discussion at the beginning of this course of the applications of evolution interesting to follow. I had, in previous contexts, applied the idea of evolution to many things, even in, for example, biology classes, and was surprised by the idea of limiting evolution to living things. I thought I understood that the scope of evolution could certainly apply to nonliving things just as well as the living. However, when I thought about this further I thought that the boundary between life and non-life might no be so clear, and this lead me to explore the idea and process of evolution in living and non-living systems. I have come to the conclusion that evolution does not, per se, apply to nonliving systems; it must, by definition, function intrinsically even in systems devoid of life, and, in theory, life will be a very persistent outcome of evolutionary processes.
My thoughts first turned to some of the examples mentioned in class of non-living things that could evolve. Books and culture were mentioned as having characters that were passed on through time, and that could change either randomly or in response to certain pressures. I thought that music should have also been included in this list, and, currently, there is test ongoing to determine if music can indeed evolve. The evolution of music through societal changes is well documented (http://asweknowit.ca/evcult/Music_Evol.shtml, Originally published in the Journal of Social and Evolutionary Systems 16(3): 273-296, 1993). However I wanted to look at a different type of study.
A group at Imperial College is currently studying the evolution of music with a specific experiment (located here: http://darwintunes.org/audio-snapshots). They begin with a set of tracks containing random sounds. They then try to evolve music over ‘generations’ by reproducing and mixing some of these random variants to create a new set. This process, which is roughly analogous to inheritance with variation and some specific selection pressure (with no filter on these results one would have random sound indefinitely), seems to have succeeded. The current sound samples, after a few hundred generations, have come to resemble music in many characteristics that were not present at the beginning of the study. These sound files have rhythm and harmonic chords and a basic melody. They have evolved and expanded into new forms, however they and the changes they undergo have all stemmed from life.
As I looked through the example of music I began to wonder where the line between systems with life and systems without life was. Viruses, for example, evolve but have no cells of their own, and their evolution is not a product of other life in the same way as music or books, however they require cellular life in order to reproduce and (thus) evolve over time. Perhaps we could look at galaxies and matter, these are certainly not biological life have evolved over time – there is information encoded in the laws of physics that causes random perturbations in galaxies to give one or the other an advantage – at least in the sense that a longer existence is more advantageous. There are many ‘behaviors’ of galaxies (see her for more information: http://www.galex.caltech.edu/) that can be observed and traced, and qualities that give one galaxy or another an apparent (and subjective) advantage over others. This concept of the evolution of matter led me to contemplate the period of time when earth did not have any cellular life but rather a “soup” of various species of molecules…
In this ‘soup’ there would have been only a few properties that would have given any particular species, or combination of species, an advantage over any other. The source materials and environmental conditions would influence the species that could be formed and thus the overall composition. Certain properties could allow species of molecule to persist longer, or determine what was present. For example, if a certain species of molecule were positively charged around certain other molecules (acidic conditions, perhaps), but neutral around a different set (basic), then the particular set that was present would determine what that species looked like (positive or neutral) and how in could interact with the other species around it. The relative stability of a species of molecule would also enable its concentration to increase or decrease, along with the ease of generation helping to determine the number in existence at any particular point. One property that would be inherently favored in this system would be a self-sustaining molecule or aggregate, if the very presence of the form caused other elements in the system to shift toward its state or composition then this form would, eventually, become ubiquitous.
One such form thought to have been naturally aggregated in this environment was lipid based “bubbles” these would enclose within a (fairly random) set of molecules, and close out anything that could not pass through the lipid barrier. As these “bubbles” moved through the environment they would incorporate more lipid or lipid-like species into the membrane. When this membrane became too large to remain enclosed it would pinch off into several smaller “bubbles,” which would all then go and repeat the cycle. The very presence of these membranes created more, and provided a sort of shelter for the very basics of metabolic reactions to begin, randomly assembling themselves by chance. Therefore I find that non-living evolution is absolutely essential to the existence of life, without the possibility then life would have had to spring into existence from some outside source, with the property of evolution isolated or restricted after that event. It doesn’t seem likely that nothing was able to change before life was present.
California Institute of Technology, GALEX-Galaxy Evolution Explorer, February 2011. <http://www.galex.caltech.edu/>
Benzon, William L. Stages Evolution of Music, 1993. <http://asweknowit.ca/evcult/Music_Evol.shtml>
London Imperial College, Darwin Tunes Project, 2009-2010. <http://darwintunes.org/audio-snapshots>