The evolution of uncertainty, about evolution

This is really a straight lift from a highly skilled writer and medical colleague, James Le Fanu. He’s used it more than once, most recently in the Charterhouse column of the Catholic Herald, but it’s no worse for that. The opening paragraph sums up my problem with all this:

The philosopher Thomas Nagel in a memorable phrase laments ‘the ludicrous overuse of evolutionary biology to explain everything about life’ — where there is nothing too sensational, extraordinary or bizarre about the living world that cannot be accounted for as having evolved to be that way over billions of years by the same known materialistic process of natural selection acting on random genetic mutation.

Well, quite.

The most obvious of those ‘puzzling questions’ that he cites is the ‘gene number dilemma’ epitomized by the most astonishing revelation of the Human Genome Project — that we have roughly the same number of genes, a modest 20,000, as the millimeter long worm, C.elegans — that is fashioned from just 1,000 cells (compared to our 60 trillion) in all, has neither a circulatory system nor internal skeleton and a life expectancy of just two weeks. Since then every newly sequenced genome has added its own further twist to this surprising lack of any correspondence between gene numbers and organismic complexity — where flies and chickens, it emerges have a third fewer genes than the diminutive C.elegans while, at the other extreme, plants such as rice and soya bean have twice as many.

The further yet more ‘puzzling question’ is the revelation of the interchangeability of the master or homeotic genes across diverse species, where for example, the same gene that orchestrates the fly’s distinctive compound type eye does so for the very different mammalian camera type eye. That interchangeability across species reaches its apotheosis with the finding that we share 99% of our genes with a mouse. How so trivial a genetic difference can generate such diversity of form defies all explanation, other than to suppose it must be ‘something to do’ with gene regulation, ‘the turning on and off of genes at different times and places in the course of development’.

The implications are clear enough. Biologists could in theory sequence every living creature on the face of the planet, but this would only confirm they all share the same core set of genes that account for the nuts and bolts of the proteins and enzymes of the cell of which all living things are made. But beyond that the really interesting question — that of ‘form’ — what it is that so readily distinguishes the elephant from the octopus, fireflies from foxes would remain as elusive as ever.

These are reasonable points, and as yet, science doesn’t have the answers. It’s not even close.

Come on then, explain us away…

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