You've done nothing but linked to papers that talk about deleterious mutations. However, no one here has ever argued that deleterious mutation don't exist, nor that they are not the majority of mutations. In regards to the third paper, that deals with the unique status of humans as the only species that can regularly neutralize deleterious mutations by dramatically altering the environment (through technology). The point of the paper is that, as a species, this could result in a loss of a large percent of the population.
quote:
If war or famine force our descendants to return to a stone-age life they will have to contend with all the problems that their stone-age ancestors had plus mutations that have accumulated in the meantime.
However, this in no way precludes the remaining human population from gaining higher fitness after the fact.
That very same author, in another paper also writes on populations' ability to evolve
quote:
Long-term selection experiments show that populations continue to retain seemingly undiminished additive variance despite large changes in the mean value. I propose that there are several reasons for this. (i) The environment is continually changing so that what was formerly most fit no longer is. (ii) There is an input of genetic variance from mutation, and sometimes from migration. (iii) As intermediate-frequency alleles increase in frequency towards one, producing less variance (as p --> 1, p(1 - p) --> 0), others that were originally near zero become more common and increase the variance. Thus, a roughly constant variance is maintained. (iv) There is always selection for fitness and for characters closely related to it. To the extent that the trait is heritable, later generations inherit a disproportionate number of genes acting additively on the trait, thus increasing genetic variance. For these reasons a selected population retains its ability to evolve.
(emphasis added)
PubMed
Edited by Stagamancer, : No reason given.
We have many intuitions in our life and the point is that many of these intuitions are wrong. The question is, are we going to test those intuitions?
-Dan Ariely
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