|Arthritic and inbred|
Image: John Reader/Science Photo Library
Every now and then, well, to be frank, more often now than then, science throws up something which makes religion and especially creationism look even more idiotic.
Take this article in New Scientist, for example.
It seems that one of the things preventing human progress after we had diversified out of Africa into the relative vastness of Euro-Asia was the fact that we tended to live in small, isolated groups. This meant there was a great deal of inbreeding with incest or near-incest being common.
This had two consequences: the first being genetic; the second cultural.
Inbreeding tends to make genetic defects more common in a population by increasing the probability of a baby inheriting a recessive gene from both its parents. It also retards the spread of new genes and so tends to reduce genetic diversity. Even when there is exchange of mates - usually females - between neighbouring groups, with small scattered groups being the norm there is still a substantial barrier to the spread of genes throughout the entire species.
This of course means we would expect to see geographical variation as localised populations evolve according to local factors and as the result of founder effects. Not surprisingly, this is exactly what we do see.
The second problem is perhaps a little harder to appreciate. Humans are almost unique in that we retain technological advances and pass them on to our offspring in the form of education and training. This meant that, before the advent of writing, skills and knowledge were retained in the minds of mostly the older members of the groups. If they were lost the group lost this skill and knowledge. This could explain why there is archaeological evidence that skills such as bone-working appear to have arisen and then been lost over time in different groups.
So, existing as we did in small incestuous groups we would have tended to suffer from lack of genetic diversity and an ephemeral technology having to constantly reinvent techniques. It was only when the population reached some critical mass that we were able to 'take off' technologically, and then greater mobility would have led to more rapid gene migration and increased genetic diversity.
This could explain why we seemed to have 'exploded' soon after the discovery of agriculture and metal working. It's an example human gene-meme co-evolution in fact.
So how does this make biblical creationism look even more idiotic?
Well, according the the Bible, humans went through two periods in the space of a couple of thousand years, and only a few thousand years ago, in which we were reduced to not just small groups of a few hundred or maybe a few thousand individuals living in geographical isolation, but to single families without even a neighbouring group a fews days walk away with whom to exchange genes and technology.
Such small groups would have been obligatorily incestuous and so biologically non-viable. They would also have quickly lost what few skills they had chanced to have developed or, in the case of Noah's tiny family, those skills and knowledge they had happened to have acquired before the Flood.
The idea that the human species, and human technology, could have evolved from such small, genetically and culturally narrow groups, not just once, but again a couple of thousand years later, is absurd.
The same applies, so far as genetic diversity is concerned, for every other species too, of course.
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