The advantages... the progress of evolution if you adapt to new environmental conditions means that you have to look for new things, because within the quasispecies you have rated everything... evaluated everything. So if you look for new mutants, they will appear at the periphery of the quasispecies. Now what is the chance that you'd find a fit mutant? People always say, 'Well, the chance to have an advantage as a mutant is very, very low, almost all mutants are disadvantages'. That's true. But the disadvantageous mutants don't appear. Why not? Because you have this very far distributed population of mutants, so the distance from the centre of gravity of the distribution is many mutations... several mutations. So at the periphery any mutant does not appear by 'mis-copying' the wild type, that means the centre of gravity. It will appear by 'mis-copying' one of the mutants at the periphery. And those mutants which are almost as good as the wild type... as the average of it, as the... which are neutral, they are populated, like the... So in other words there is a rating within the quasispecies that the good mutants are populated... the neutral mutants are populated almost like the wild type, whereas the deleterious ones only are just formed and then disappear so they are present in very low population. So what you produce at the periphery are mutants of the good ones. And by similarity methods the probability that you get a better mutant from a good one is much larger than to get a better one from a bad one. So in other words, there is a very efficient way of testing for mutants, and we have studied this. In the experiment I have mentioned, within seventy minutes you got this completely different molecule which was able to resist to the degrading enzyme, and so how could you do that other in another way? The number of possible mutants there is astronomically high, but the system finds the right ones.  That's one of the important points.