Straight flush: evolution, complexity, and progress
Stephen Jay Gould has long and consistently maintained that it is a “false and self-serving notion that evolution displays a central and general thrust towards increasing complexity, when life, in fact, has been dominated by its persistent bacterial mode for all 3.5 billion years of its history on Earth” (“Cope’s Rule as Psychological Artifact,” Nature, 16 January 1997).
The operative word here is, I think, dominated. If Gould is arguing that dominated means that bacteria have been around for 3.5 billion years before man and are likely to be around for at least that long after him or that they are far more ubiquitous or that the total biomass as well as number of Earth’s bacteria is vastly in excess of that of humans, I can find nothing to cavil about.
But of course Gould’s assumption and advocacy go far beyond. He means that bacteria ruled Earth from the start, rule it now, and shall go on ruling it until the sun becomes a red giant, however we define the term rule. (Gould’s actual phrase is “until the sun explodes.” In fact, the sun isn’t massive enough to explode, but it will expand and, so far as Earth is concerned, it will not make all that much difference to our star going supernova.)
I do not know what meaning evolution through natural selection has if it does not include in that meaning a gradual (perhaps also a punctuated) development in complexity, on the large, big-picture scale of view. It is, I think, not possible to look at the paleontological record over the long term and not see a more or less regular increase in complexity among living things. I do not know what else evolution is, for it certainly is not mere change. It is clearly, self-evidently, much more.
Something else Gould doesn’t believe in is progress by evolutionary development. Again our point of view depends on what we take the word – in this case that troublesome term progress – to mean in the context we are dealing with.
One thing we should not do is equate mere increasing complexity with progress, whether in biology, architecture, women’s fashions, or anything else. The best definition of evolutionary progress by means of natural selection that I can think of is a growth in the overall complexity of organisms that allows them to exercise increasing control over their environment. Some of us call this progress. If this is not progress then I do not know what the word means.
A third word Gould defines in a way I find galling is chance. In Wonderful Life, Full House, and elsewhere, Gould reminds us that if we turn the clock back four billion years and start the evolutionary ball rolling again on Earth, the results will be very different. They will be different each time we run the game of evolution through. This is because natural selection will be working on different life forms, different because conditions and contingencies will be different each time, and over time these differences will accumulate and accelerate, like compound interest. But Gould does not add that this is because natural selection will be working precisely and punctiliously the same as it always works, as it must work, for natural selection must obey its own rules and can never alter or ignore the rules, for then it would cease being natural or selective. Chance and contingency will throw up different life forms each time we play the game, because conditions are never exactly the same twice. But whatever it works on, natural selection will work on them by the same old rules because the rules never change and the first rule is: improvements remain.
Each step in the game of evolution through natural selection is not a matter of going back to start. There is incremental advance – there is, dare I say it, progress – going on, bit by bit. This advance, this progress, this increase in complexity and in control is not invariable; there are long periods during which nothing much happens and there are many instances when things seem to be backing up, but, looked at overall, life develops. It has been developing these last 3.5 billion years and it will go on developing for as long as conditions permit. This is the essence of evolution. Some things, like bacteria, have stayed comparatively simple through their entire history. Other things have not. Some, such as parasites and that ultimate of all parasites, viruses, have retrogressed. But, by and large, most life forms have, if only in a slipshod, haphazard way (which seems to be nature’s manner of doing things), grown more complex and more in control of their environments.
Of course, the more complex a life form gets, the more dangerous the game becomes, because complexity means that the life form is more vulnerable to change, to contingency, to being hit on the head by a large asteroid. This is why bacteria have managed and will continue to manage much better than any other more complex, more “progressive” life forms, as far as continuity and survival down the eons go. The less complicated you are, the safer. But – and this is the point – nature has never operated on the basis of safety first. It seems to enjoy (if I can for a moment commit the sin of personification) playing the game of Life Poker for high stakes, and the greater the risk the more fun it seems to get. The game is at its riskiest now, with the recent emergence of a highly complex life form possessing a rudimentary intelligence that is capable of destroying itself and, just possibly, all other complex life forms on this planet. Its brain is an extremely complicated organ and, as one might expect, the creature appears top-heavy with it and finds great difficulty in coping with it, or even understanding how it works.
Let us pursue Gould a bit further and farther out.
Consider life forms on other planets or their moons. The same criteria must apply as apply here. Whatever the particular qualities and characteristics of the life forms, the rule will be that those that fit best into their environment will be the ones that stick around – until something happens to the environment, at which point all that wonderful adaptation will become a noose around their collective neck. This is why we have extinctions, as well as development, in the course of natural selection. It’s not a case of our knowing what particulars of evolutionary form these extraterrestrial organisms will take, just as there is no way of knowing what will result right here on Earth if we play the game again from scratch, but we know that natural selection will be operating. The natural laws, rules, and universals in time and place will function, whenever and wherever these matters arise in the universe.
If we contend that we do not know anything about the particular life forms on Planet X or Moon Y, we can surmise nothing about them, we are almost certainly wrong, for we can surmise that evolution by means of Darwinian natural selection is operating on them. And even if, as with the one example we have, we know the life forms and their history (more or less), and we still are unable to make much in the way of predictions about what these forms will be like in a million years, it is no great matter. We know that in a million years and in a billion years the life forms will still be answerable to natural selection, even if one of those life forms becomes so advanced it is able to substitute its own selectivity and create faster racing horses, sillier looking dogs, new species of bacteria, and even new species of itself. Even if it creates life out of silicon, rather than the same old carbon, or clones the old into the new, the same rules of the game will apply, because artificial selection, no matter how clever, or how stupid, cannot alter those rules, it can only use them this way or that.
We could, if we were stupid enough, set out to eliminate those forms that are best adapted and see to it that creatures out of tune with their surroundings were the only ones to survive (we have gone a long way down this path with our domestication of plants and animals, where the most naturally unfit survive), but this would necessitate a constant, never-ending intrusion of artificial selection by us into the natural rhythm. The moment this interference ended, all the old patterns of natural selectivity would reassert themselves with a vengeance, because we could never succeed in destroying the rules but only in keeping them dormant and hiding, ready to pounce back the first chance they got, and turn our foolishness and arrogance into bloody fruition.
Natural selection will always determine what to do with the results that chance and contingency throw its way. Order is the key to the game. Of course there is chance, randomness, there are accidents. But there is unalterable law beneath and beyond them.
Gould’s conclusion, that things will work out differently with each evolutionary throw of the dice, is obvious, and therefore uninteresting and lacking in real significance.
Nothing is written. Nothing is preordained. We know that, should evolution begin all over again, the outcomes along the way could not be the same. That is not the question we need ask, and seek answers to. The question is: How different would it be? How different could it be? What are the limits of the possible divergences? Of course there is chance. How could there not be? But there is also necessity. It is the interplay between them that beguiles us. It is this we need to know.
Lewis Thomas describes in The Fragile Species his utter amazement that life on Earth has moved, in a mere 3.7 billion years, from archaebacteria to the Mass in B-Minor.
If that is not development, growth in complexity, advance, progress, then what is?
Ralph Estling writes from Ilminster, Somerset, U.K.
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