Once humans get established in space, evolution will take over – and take off. Before then, however, and likely even before we leave the planet, I'll bet there's going to be a lot of intentional, as opposed to natural, genetic alteration. It will start with efforts to eliminate undesirable genes that predispose one to heart disease, cancer, or genetic disorders. But while we're at it, why not also select for blue eyes, taller, more muscular frame, greater intelligence, and anything else people might want their children to have? Some people won't want to go that route, preferring to leave things to nature, but their children will be at a disadvantage to those whose parents have selected superior genes. That could lead to speciation along several lines.
Read the rest here.