Cells and Natural Selection

Over at the shillelagh-wielding Mike Flynn’s Blog, he posts some fascinating thoughts on natural selection and molecular biology. Read that. Here’s a comment I made:

You hit upon a whole bunch of issues I’ve been pondering for years. First off, the Darwinism of Dawkins (and E.O.Wilson) was a response to the happy-happy talk of the proto-environmentalist, who wanted to see harmony in nature, even in natural selection. Wilson and Dawkins were defenders of orthodoxy (and reason) against what might be called a misguided teleology of environment – that the various competing parts of an environment *want* to be in harmony.

So, we get the Selfish Gene. And then, the Extended Phenotype, which takes the concept of a the genes of within an individual member of a species – and extends it to the environment. Hmmm. To be sure, Dawkins is not trying to reestablish the hippy-dippy harmony he and Wilson just shot down on a more rational, mechanistic basis. Rather, he’s trying to show how some of the odder behaviors and structures in nature can be explained within his theory.

But, it seemed to me – and here’s the tie-in with your thoughts above – he didn’t go far enough. And here I must apologize, for I am not nearly as widely read as you on this topic, and have not yet had a chance to review the materials you’ve linked to above. Perhaps this all is discussed at great length in literature I’ve yet to read.

Molecular biology is the place to start any evolutionary discussion, because it is the molecules that make up the cells and creatures that have undergone whatever mechanisms are at play for the longest time and under the most varied circumstances. Even a single celled organism represents, under Darwin via Dawkins, an apex of evolution – it is the inconceivably complex result of *some* processes, having taken place over at least a billion years. Unlike modern animals and plants, a single-celled organism is dealing directly with an environment chock full of free-floating genetic stuff, stuff which can invade or be invited into a cell. Such invasions and invitations, along with mergers and acquisitions, as it were, were and are where the action is, and has been for a couple billion years, and at least potentially accounts for ‘mutations’, whatever that term means is this context. Evolution, under any mechanism, should first and primarily be concerned with how cells, or even smaller units such a viruses, deal with this.

All the characteristics that Darwin observed, all the diversity and behaviors in animals and plaints, are like the paint on a house. The fundamental interesting part about a finch cracking seeds is really how it is that the finch can digest those seed and build ‘finch’ out of them. Read once about how mammals replaced birds as the apex predators in South America a few million years ago due, they supposed, to a slight advantage in metabolism. And how placental mammals have replaced marsupials almost everywhere, and for the same reason. How many other ‘survival of the fittest’ battles have been decided based on how well some fundamental molecular interaction, including the exclusion, inclusion or repair of genetic materials, takes place? All of them?

Further, once you start thinking this way and building up to appearances (1), a series of questions arise:

1. Is hybrid vigor an adaptation? It has generally been thought to be an artifact, something that just happens when two populations who have not interbred much meet – small genetic differences have accumulated in the different populations which, when combined, tend to produce results farther out along the bell curve’s tails for whatever traits you want to look at. But what if, instead, hybrid vigor is a strategy, so to speak, developed on a molecular level but now writ large? Perhaps cells faced with strange but not too strange genetic materials floating about, used that not too strangeness as a trigger to accept the materials, incorporate them – and then to do – execute the code for – whatever difference are found. The mere existence of such different code is solid evidence that it is not fatal, and may be helpful. By accepting and executing it, the cell is most likely to improve its own survival chances.

Take that basic mechanism, rinse, lather, repeat a few billion times, and you might get a tendency for macro flora and fauna to use those differences as triggers: the presence of new code in the new population might trigger, for example, a tendency toward greater size and strength. For the presence of different code tells ‘our’ DNA two things: that this code isn’t fatal and may be beneficial, but more important, that there’s been a disruption in the environment – a population is now here that wasn’t here before.

Let’s take people as the go-to example: Looked at from the genetic/molecular point of view, the differences in genetic code represent successes – the carriers have survived and reproduced in their environment. Therefore, incorporate and execute those changes as far as possible. BUT: the differences also represent a disruption – something has happened to break down whatever it was that kept the populations apart long enough for the genetic differences to develop. Therefore, run the ‘superior size and strength’ program, because those features have proven valuable over time for survival at times of disruption in breeding patterns. Also, run the ‘beauty’ routine – hybrids, curiously enough, tend to be more physically attractive as well as larger and stronger. (This also speaks to this theory which is mine, insofar as the non-hybrids find hybrids more attractive as well – meaning that, encoded in our genes is a ‘desirable to breed with’ response to hybrids, even if we aren’t one ourselves.)

2. Similarly, and more to the point of Mr. Flynn’s essay, what if adaptability of form & behavior is an adaptation? This one seems almost inescapable from whatever mechanisms one starts with: Finches’ genes have been selected (under one set of mechanisms) to keep a ‘tool set’  of variables in storage but at the ready, as it were. Something changes in the environment – say, the finches are let loose in Hawaii –  triggering the roll-out of these stand-by tools in a way that, I imagine, might please Lamarck. Similarly, cichlids are famous for rapidly ‘mutating’ to fill every niche in a new environment. The African Great Lakes are all very new, yet each is filled (or was, until the Nile perch ate most of them) with cichlids. These fish had, at most, a few centuries to evolve. Also, genetically, these different ‘species’ are all but identical. This would seem possible only if the fish was ‘designed’ to ‘evolve’. Again, this only works if the ‘tools’ are there (or readily available) and if an environmental trigger can cause their roll-out in the next generation.

1. Hey! We just pulled an Aristotle: started with what is most knowable to us – large-scale features of plants and animals – and proceeded to what is most knowable in itself – the molecular mechanisms from which those features spring. Now, we can do some Science!


Author: Joseph Moore

Enough with the smarty-pants Dante quote. Just some opinionated blogger dude.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s