I would say that it is some sense obvious that higher intelligence is possible, because the process that led to whatever intelligence we have was haphazard (path-dependent, stochastic, and all that) and because what optimization did occur was under severe constraints - some of which no longer apply. Clearly, the best possible performance under severe constraints is inferior to the best possible with fewer constraints.
So, if C-sections allow baby heads to get bigger, or if calories are freely available today, changes in brain development that take advantage of those relaxed constraints ought to be feasible. In principle this does not have to result in people who are damaged or goofy, although they would not do well in ancestral environments. In practice, since we won't know what the hell we are doing... of course it will.
Still, that's too close to an existence proof: it doesn't really tell you how to do it.
You could probably get real improvements by mining existing genetic variation: look at individuals and groups with unusually high IQs, search for causal variants. Plomin and company haven't any real success ( in terms of QTLs that explain much of the variance) but for this purpose one doesn't care about variance explained, just effect size. A rare allele that does the job would be useful. I'd look at groups with high average IQ, but at others also.
There are other possible approaches. If you could error-correct the genome, fix all the mutational noise, you might see higher IQ. You could dig up Gauss and clone him. My favorite idea is finding two human ethnic groups that 'nick' - whose F1 offspring exhibit hybrid vigor.
As for the singularity: I could, I think, make a pretty good case that scientific and technological progress is slowing down.
Thanks for the response.
(Consider the following question in a Bayesian spirit, i.e. the spirit of giving a probability to any event, even if you don't have an associated frequency for it)
If you had to bet on whether the technology for these genetic engineering efforts (NOT the political will) will be ready by e.g.
2030, 2040, 2050, 2075, 2125,
what kind of odds/probabilities would you bet at?
Edit: Q&A is now closed. Thanks to everyone for participating, and thanks very much to Harpending and Cochran for their responses.
In response to Kaj's review, Henry Harpending and Gregory Cochran, the authors of the The 10,000 Year Explosion, have agreed to a Q&A session with the Less Wrong community.
If you have any questions for either Harpending or Cochran, please reply to this post with a question addressed to one or both of them. Material for questions might be derived from their blog for the book which includes stories about hunting animals in Africa with an eye towards evolutionary implications (which rose to Jennifer's attention based on Steve Sailer's prior attention).
Please do not kibitz in this Q&A... instead go to the kibitzing area to talk about the Q&A session itself. Eventually, this post will be edited to note that the process has been closed, at which time there should be no new questions.