Put in my place

. . . imagine a puddle waking up one morning and thinking, "This is an interesting world I find myself in, an interesting hole I find myself in, fits me rather neatly, doesn't it? In fact, it fits me staggeringly well! Must have been made to have me in it!"

Douglas Adams

It took me a while to work out what was bugging me, but I think I've got there. We were at Skeptics in the Pub rambling about epistemology and other such nonsense, when for whatever reason, somebody felt the need to bring up the example of "chemical" versus "natural" -- something that I discussed here a few weeks ago. I did my quick piece on "flipping the Necker cube" and looking at the nasties in our environment in terms of our evolution: nothing is intrinsically healthy or harmful, it is only in the context of our evolved anatomy, physiology and biochemistry that it becomes so.

I was up against quicker witted and more articulate fellows than myself, and after a long day, a couple of hours of Bad Astronomy, and more than a couple of pints, I was not able to adequately put into words just why the response to this point was wrong. Since the point about flipping theNecker cube is one that I have also made on the blog, I thought I would discuss it again here, in-case anybody else has misunderstood the point that was being made.

First, a rough characature of that response: by talking about evolution and nasties I was elevating humankind to a position that we don't deserve. Man is a tiny part of life on earth, and we shouldn't flatter ourselves to believe that the universe is deliberately out to get us, any more than we should flatter ourselves by believing that the world was made to have us in it. God is famously fond of beetles and bacteria, after all.

Of course, the problem, so obvious now, is that the Necker cube has not been flipped at all. We're still trying to answer the question of why the nasties are nasties by looking at how they got to become nasties. The other side of the cube is to try to answer the question of why nasties are nasties by looking at how we evolved. This means recognising that we have been built, bit by bit, from scratch. Every system, organ, tissue, cell type, metabolic network and enzyme has a birthday, somewhere in the depths of time. They have been shaped by selection to perform a function with some minimum of efficiency, and to have a minimum of robustness in the face of countless environmental variables.

And it is only by having encountered particular values for those variables that evolution can have prepared us for them. Evolution has no foresight and goes no further than those minimum values. It picks the first successful candidate solution that it finds, and it's just luck if it solves more problems than were asked of it. If a population encounters a novel chemical, sourced from a plant for example, evolution will not have prepared the population for that chemical. That does not mean that we are elevating humankind by suggesting that the plant is producing the chemical with that specific population in mind.

Not convinced? It helps if only one of the parties is evolving, so we'll ignore plants, bacteria, and xeno-biochemicals altogether, and just watch how man performs against the elements. An enzyme that has never encountered a particular pH or temperature, for example, can reasonably be expected to perform poorly under such conditions. Break, even. We are not witnessing a conscious decision on the part of God or Mother Nature or the Universe to challenge us with extremes of pH; it is merely the outcome of an unconscious "decision" not to prepare for such events. Acidophilic archaea, organisms that have evolved in the context of extremes of pH, have enzymes that are similarly unprepared for the conditions in which we live.

When you look at it from this angle, it doesn't just seem obvious that species are adapted to that which they have experience of, and vulnerable to many things that are unfamiliar to them. It seems absurd to even bring up the issue of whether nature gives a damn about us. It is we who are giving the damn. And that is the point of Douglas Adams' puddle.