Hypermutation is a specific process where segments of DNA are shifted aroundvia, IIRC, things called transposons. I could of sworn I had a link to an article, but I seem to have misplaced it. It has nothing to do with chemicals or toxic stress but rather a built-in part of the DNA replicating mechanism, and completely sperate from normal 'damage' mutations.

By swapping around existing DNA the function of the gene can be changed.


"Stress" can mean a variety of things. Certainly toxic stress will induce or increase mutations - such as when bacteria are deliberately poisoned in lab experiments, they will mutate to survive. In one (again, unfortunately, link misplaced but the whole article is copied somewhere over at Bible Babble) most of the surviving bacteria came up with the same mutation to survive the poison. It was also shown experimentally that under these circumstances beneficial mutations were far more prevalent than harmful ones.

This is, of course, an extreme example of stress, but since it can be seen that it is at times of 'stress', usually through environmental changes, that most evolutionary 'explosions' occur, the same mechanism is presumably at work. Any time the majority of a population is killed, such as during a mass extinction, or for example when an infection is treated with antibiotics, you would expect such mechanisms to be at work.


You cannot compare a human to a reptile. Our common ancestor is far too far back - hundreds of millions of years. If the lizard switched back on a dormant gene, or aquired a mutation of one of its genes doesn't prove that humans could or ever did do it. Even hermaphrodite humans, with male and female sexual organs, are sterile.

I can, for instance, see a parallel with Crocs and Bees, where unless a certain trigger is aquired by the egg, in one case fertilisation, another a 'switch' during incubation, the offspring are female. But the Croc females are not clones, whereas the bees are. Some fish can change sex, as can some amphibians. Humans cannot - even if they have a "sex change" it isn't a real change - they can't then reproduce as the new 'sex' they are. So, even though these cloning lizards are reptiles, and far closer to us than insects, linking that to humans is impossible.

It is irrelevant anyway - you're twisting away from the issue again. Your question says "quit". You are asking when humans stopped cloning, ie, that that was the initial state. It never was. In fact, I doubt it was for any vertebrate, from what I know of paleontology. That some freak mutations have managed to get some species to revert to cloning is another matter entirely.


DNA is not reproduced entirely faithfully anyway - errors creep in. I would not like to say for sure, as it is not my field of expertise, but I would suspect that as the generations of clones continue, the accumulation of random mistakes during the cloning will continue. Different parts of the DNA strand accumulate changes at different rates, so I could not say at what sort of a rate these changes would be aquired, but I have no doubt they would creep in over a number of generations.
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Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. -
Albert Einstein