fitness in the wild is very seldom improved by loss-of-function mutations, whereas fitness for our purposes, starting from the species that have been evolving for fitness in the wild, very often is.
There's no reason evolution would have already have optimized for all the intelligence-related alleles; if it had, they would have reached fixation.
Rapid success at breeding larger corn kernels is not going to generalize into rapid success at breeding ubermensch.
I think it is. All the genetic data seems to point to: much of intelligence is genetic, highly polygenic, not fixated, and additive. All of that translates to breedability: we have a lot of easily identified variants present in only parts of the population; hence, breedable.
There's no question that evolution can continue. The issue is that the rate you can attain for different traits differ. For example, evolving smaller animals from larger animals (by a given factor) is an order of magnitude faster process than evolving larger animals from smaller animals. ( http://news.ucsc.edu/2012/01/body-size.html ). I think you wouldn't disagree that it would be far quicker to breed a 50 point IQ drop than 50 point IQ rise?
we have a lot of easily identified variants present in only parts of the population
I guess you refer to those ...
A long blog post explains why the author, a feminist, is not comfortable with the rationalist community despite thinking it is "super cool and interesting". It's directed specifically at Yvain, but it's probably general enough to be of some interest here.
http://apophemi.wordpress.com/2014/01/04/why-im-not-on-the-rationalist-masterlist/
I'm not sure if I can summarize this fairly but the main thrust seems to be that we are overly willing to entertain offensive/taboo/hurtful ideas and this drives off many types of people. Here's a quote:
The author perceives a link between LW type open discourse and danger to minority groups. I'm not sure whether that's true or not. Take race. Many LWers are willing to entertain ideas about the existence and possible importance of average group differences in psychological traits. So, maybe LWers are racists. But they're racists who continually obsess over optimizing their philanthropic contributions to African charities. So, maybe not racists in a dangerous way?
An overly rosy view, perhaps, and I don't want to deny the reality of the blogger's experience. Clearly, the person is intelligent and attracted to some aspects of LW discourse while turned off by other aspects.