Thursday, September 10, 2015

On the Fact that Most Mutations Tend to Be of a Deleterious Nature

This is probably the largest obstacle for the neo-Darwinians to avoid; the fact that random mutations are the central mechanism (far more important than natural selection, from my viewpoint) for evolution to be viable and that there would literally have to be tens of thousands of them operating in a beneficial manner for a cross-species event to materialize, etc..


Rusty Shackelford said...

Would you classify WD as a mutation?

BB-Idaho said...

In pondering the good v bad mutation relation to evolution, I'm thinking that most
mutations are recessive: like Tay-Sachs disease, if two carriers of the recessive
gene mate, generally the offspring are not viable long enough to reproduce. There is some evidence, such as generally increased intelligence, that the mutation has
postivive/negative effect and since it has been confined to the Ashkenazi Jewish population, genetics studies are relatively focused. However, it's fatal impact on
individuals receiving both recessive genes reduces its occurance over time, and likely it disappears over the long run. Conversely, the few mutationswhich offer species improvements may be recessive as well, but the phylogenetic expression not
only survives but prospers, thus it becomes widespread and over the long term becomes non-recessive. Evolutionary detail has its complexities, and as you and others note, lack of data, particularly in the far past, requires assumptions which
may or may not hold, but newly discovered genetic methods should clarify (if not at
first confuse) some of these concepts. For example, recent extensive genetic analysis of recovered ancient DNA from Denisovan hominims has revealed
a niche hominid somewhat between the Neanderthal and concurrent Sapiens in late Pleistocene Europe. The data keeps coming in and various POVs chew on it before
it becomes mainstream or obsolete.