I don't know whether I believe this. Which limitations, exactly? Would humanity no longer be human if AIDS ceased to exist? What about Irritable Bowel Syndrome? Was Einstein less human? If not, then why would humanity be less human if everyone were that smart? It may be true, as Dirty Harry said, that 'A man's got to know his limitations.' But does that mean that a man is his limitations? Some people think so, but I'm not so sure. Others think that overcoming limitations is what's central to being human. I have to say that find that approach more persuasive.
These topics (well, probably not the Irritable Bowel Syndrome) were the subject of a conference at Yale on transhumanism and ethics. The conference was the subject of a rather good article in The Village Voice, which reports that many in the pro-transhumanist community expect to encounter considerable opposition from Luddites -- and, judging by the works of anti-technologists like Francis Fukuyama and Bill McKibben, that's probably true."
It's easy to tie this in with history of science stuff. Glasses, wristwatches, medications are all attempts at improving our limitations. Reynolds writes about gene doping for the beijing olympics -- not sure what that is but it prompts: how can you penalize someone who was bred to compete?
Reynold's conclusion is that the forces of human improvement will win out over the luddites, like always. But if the pace of improvement is too fast there could be a big backlash. At least, until the fearful realize they're falling behind.