One Step At A Time

Were Jews ever really slaves in Egypt, or is Passover a myth? - Haaretz Daily Newspaper | Israel News

Reading the above excellent article by Josh Mintz who describes himself as a Jewish World Blogger, it reminded me of a metaphor Richard Dawkins used in one of his books concerning his disagreement with Stephen Jay Gould about Gould's Punctuated Equilibrium theory of how evolution progresses.

As this article points out, there is absolutely no archaeological evidence to support the story of the escape of the Hebrews from slavery in Egypt and, more relevantly for Dawkins' metaphor, none at all to support the story that they wandered about in Sinai, taking forty years to cross it to reach 'the promised land'.

So, what has this got to do with Gould's 'Punctuated Equilibrium'?

Gould had suggested, following his study of the Burgess Shale fossils, that evolution did not proceed by a gradual accumulation of small changes over a long time but that species had long periods of stasis, followed by periods of rapid - in geological time almost instantaneous - change. He called this 'Punctuated Equilibrium' and relied almost entirely on fossil evidence to support it.

The fossil record is inevitably rarely better than a series of randomly spaced snap-shots of the organism's evolutionary history and in any case, there is nothing in Darwinian evolutionary theory which requires a species to evolve at a constant rate. Indeed, if the environment remains unchanged for a long period there is nothing to drive evolutionary change apart from genetic drift. (I have previously blogged in Show Me The Transitional Forms on how the fossil record can give a misleading picture of evolution.)

Dawkins illustrated this with the biblical story of the Hebrews wandering about in Sinai and taking forty years to cross it. Supposing there had been some archaeological evidence that they had camped over-night or for a few days, built camp-fires and cooked food (so leaving wood ash and maybe the bones of the animals they had eaten) and buried their dead. What would archaeologists make of these finds, scattered as they would have been with several miles between them and not even progressing in any particular direction?

Supposing they had found these artefacts and had been able to date them accurately. Would any rational archaeologist suggest that they proved the Hebrews stood still for a long time and then jumped in one huge stride to the next camp-site? Would they conclude that they had proved that the Hebrews had not walked across Sinai one step at a time but had used some other novel form of locomotion involving flight or teleportation?

Of course not. Mind you, that would explain why they walked for 40 years yet had no obvious material or opportunity to make new shoes to replace old, worn-out ones, but that's another matter.

Why then conclude from a snap-shot of evidence of a species evolution that it had not progressed one step at a time but had used some other form of evolution? With no obvious mechanism by which this could be accomplished, and when the Darwinian idea of accumulating small change is perfectly adequate, why insert a hypothetical mechanism for what appeared to be nothing more than a desire to come up with a different theory of evolution?

---