Comment by gcanyon

This argument seems, frankly, absurd to me on multiple fronts.

First, it assumes that lack of genetic diversity in humans would be a serious handicap, when we're considering humans that are capable of making interstellar journeys. Assuming that genetics are going to be an issue compared to traveling/surviving 7 or more light year-journeys is a leap.

Second, it assumes that if this were a problem, humans would/could think of no way to address it. Two solutions come immediately to mind: 1. Choose the people making the journey more carefully to ensure diversity 2. Send frozen embryos chosen for diversity along.

Third, it ignores the time scale over which something like this would be likely to happen. Of course, you can't guarantee that beneficial diversity will re-occur, even over centuries, but a little effort on the front end combined with the time it would take to continue on to the next hop seems hopeful.

Fourth, it ignores the possibility of repeat journeys. If we're really going to constrain the available destinations in the way presented, it's silly to propose that there will be just one colonizing event.

But really, the first solution is all you need. The idea that we'll be able to survive multiple generations in space but not handle genetics issues is, just, a real stretch.