I am going to commit the middlebrow dismissal sin here (and compound it by not reading the actual paper; but, the abstract doesn't make this appear to be a paper worth spending undue amount of time on).<p>Evolution is a process that occurs over vast amounts of time. Trying to draw conclusions about the fate of human evolution based on developments of the last hundred years would be remarkably foolhardy. You might as well try to plot a bee's course based on the last microsecond of its movements.<p>Sure, people with genetic weaknesses that might have been quickly selected against 10,000 years ago are now able to live long & full lives, naturally leading -- for now -- to the continued spread of those genetic variations. However, humans are also right now unique on the planet for our ability to alter our own genetics; I have no doubt that within the next hundred years, within the very next evolutionary microsecond, we will have the technological ability to choose the course of our own evolution.<p>And I doubt very seriously that there will be much room for serious disease in that future.
Neuroskeptic has a good response to these articles at <a href="http://neuroskeptic.blogspot.com/2012/11/were-probably-not-getting-dumber.html" rel="nofollow">http://neuroskeptic.blogspot.com/2012/11/were-probably-not-g...</a>, essentially arguing against Crabtree's thesis for being too speculative.
<i>which may have weakened the power of selection to weed out mutations leading to intellectual disabilities</i><p>What the hell does it mean? Smart people aren't breeding? Intellectually disabled people are breeding?