Hi Raoul

Perhaps 'chance' is misunderstood because it's not well understood. It's not 'causeless' just unpredictable. And if people knew how much it drove the micro-processes of the world it wouldn't seem so strange. We assume gas molecules in a container will, by chance, exert on average an equal force on all the container's walls - in principle they could all hit one side at the same time, but that configuration is so unlikely as to be unobservable.

That's my main issue with calling evolution 'random' or 'by chance' because 'lucky' (i.e. successful) mutations are ridiculously unlikely for major macro-changes in an organism's phenotype, and people imagine that's how evolution progresses. But that perception couldn't be more wrong because the main powerhouse of evolutionary change is small increments - base-pair changes, duplications, and regulatory region modifications. Most of the changes can't be seen in the phenotype except by looking at the population as a whole - the broad range of variation is the collective stock of mutation.

A population doesn't change by chance either - instead a direction has to be given to the population, some set of genes has to produce a survival/reproductive advantage and then the gene frequencies shift, the phenotype 'morphs' into something new. Just like the individual particle motions of an exploding mix of fuel-air are random, but their overall expansion in an engine cylinder has direction, so too the response of genotypes & phenotypes to a selective pressure.