A while back I was out with some members of my family and the topics of evolution and genetics came up. A younger family member, with a lot of curiosity asked, what I found to be an interesting, if not unsettling question:
“If someone imprisoned a bunch of people and forced the to dig constantly, would they eventually evolve into, superhuman digging machines?”
My answer, was only if digging ability was somehow linked to reproductive success, in which case, you would have a sort of bizarre selective breeding program for humans. I went on to point out that such of an experiment would of course be highly immoral, coercive and unethical in countless ways. Anyone who has read my other entries knows that I am a strong proponent of personal freedom, and an opponent of locking people up for arbitrary reasons. That said, ethical concerns aside, the idea of selectively breeding people for arbitrary traits is definitely possible (it does not violate any of the laws of physics), and it would not to be very different from the process through which develop most of our domestic dog breeds. Carl Sagan’s book The Pale Blue Dot, discusses, a similar situation occurring sometime in the hypothetical distant future, in which humans, traveling long distance in space vessels or settling on distant planets, become isolated from the rest of the gene pool for successive generations. He noted that these populations, would develop distinct physical features and after a long enough period, no longer be able to interbreed with the rest of us.
It would however be a very slow process, since humans take an usually long time to reach reproductive age, and the hypothetical captor would not likely live to any tangible result of this albeit highly immoral, experiment. Furthermore, even after hundreds if not thousands of generations, a new type of human, especially suited to digging did develop, there is no telling, what unintended impacts the process would have. Often breeders find desired traits to be linked to seeming unrelated ones. In a ongoing Russian study, Silver Foxes were selectively bred for approachability by humans. As the study progressed the decedents of these foxes developed traits and behaviors similar to those of domestic dogs. As one experimenter explains “ eager to establish human contact, whimpering to attract attention and sniffing and licking experimenters like dogs. They start displaying this kind of behavior before they are one month old. In addition to the desired changes, the foxes developed spotted coats, raised tails, floppier ears and the females began going into heat every six months rather than yearly. None of these physical changes was actively selected for but instead had piggy-backed onto the traits that were selected for.
In a similar experiment with human beings all sorts of unexpected traits could develop through similar means, and some of these may in fact be harmful. Purebred animals are often vulnerable to health problems that there more well-rounded relatives do not have, and humans have selectively bred countless live forms, that likely could not survive, without humans to care for them.
This is also a reason, why even though it may be technically possible to develop a purely voluntary selective breeding program for people, it could develop numerous undesired results. Natural selection tends to develop life forms that are well suited to the environment they live in and this is true of people as well. Even if such a program were established it strikes me that it would be difficult to keep the successive generations motivated to participate in it. As people tend to prefer making their on choices when it comes to reproductive matters.
So, to answer the initial question, it would certainly possible to selectively breed people, corrosively doing so would be both unethical, immoral, slow, and plagued by unanticipated consequences. Furthermore a voluntary attempt, at such a project is also not likely to work, and also likely to be plagued by unanticipated consequences. Simply put, it is best to allow people to make their own choices.