Evolutionary Causality

Evolutionary Causality

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Were the Earth to be started over again with all its physical features identical, it is extremely unlikely that anything closely resembling a human being would ever again emerge. There is a powerful random to the evolutionary process. A cosmic ray striking a different gene, producing a different mutation, can have small consequences early but profound consequences late. Happenstance may play a powerful role in biology, as it does in history. The father back the critical events occur, the more powerfully can they influence the present.

The pattern of evolutionary causality is a web of astonishing complexity; the incompleteness of our understanding humbles us. Image: © Elena

For example, consider our hands. We have five fingers, including one opposable thumb. They serve us quite well. But I think we would be served equally well with six fingers including a thumb, or four fingers including a thumb, or maybe five fingers and two thumbs. There is nothing intrinsically best about our particular configuration of fingers, which we ordinarily thing of as so natural and inevitable. We have five fingers because we have descended from a Devonian fish that had five phalanges or bones in its fins. Had we descended from a fish with four or six phalanges, we would have four or six fingers on each hand and would think them perfectly natural.

We use base ten arithmetic only because we have ten fingers on our hands (the arithmetic based on the number 5 or 10 seems to be so obvious that the ancient Greek equivalent of “to count” literally means “to five”.

Had the arrangement been otherwise, we would use base eight or base twelve arithmetic and relegate base ten to the New Math. The same point applies, I believe, to many more essential aspects of our being – our hereditary material, our internal biochemistry, our form, stature, organ systems, loves and hates, passions and despairs, tenderness and aggression, even our analytical processes – all of these are, at least in part, the result of apparently minor accidents in our immensely long evolutionary history.

Perhaps if one less dragonfly had drowned in the Carboniferous swamps, the intelligent organisms on our planet today would have feathers and teach their young in rookeries.