Watch Live Tonight: The Challenges of Interstellar Flight

Anthropologist Cameron Smith talks about the cultural and genetic implications of long-term space missions

Cameron Smith, author, anthropologist. Courtesy of Perimeter Institute

If humanity ever travels to another star, the trip could take generations. Such a journey would present serious technological challenges, of course, but the social difficulties of keeping a large population happy and healthy on a spaceship could be no less daunting. Anthropologist Cameron Smith of Portland State University has studied these questions and will discuss the biological and cultural science of long-term space travel during a lecture at the Perimeter Institute for Theoretical Physics in Ontario that will be broadcast live here on this page.

Smiths talk, Interstellar Voyaging: An Evolutionary Transition, will begin Wednesday at 7 p.m. ET as part of the Perimeter Institutes public lecture series presented by Sun Life Financial. The lecture will be viewable on this page as well as at http://www.perimeterinstitute.ca. Online viewers can pose questions to Smith by tweeting to @Perimeter and using the hashtag #piLIVE.

Scientific American spoke to Smith about what it will take to mount an interstellar voyage. Below is an edited transcript of the conversation.

Is it really plausible to discuss a multigenerational space journey? Are we even close to being able to do something like this? Im presuming that the physics people will give us high-speed propulsion. Im playing the same game as [space research organization] Icarus Interstellar. Their project is not to build anything now. They want to give humanity the option at the end of this century, in a hundred years from now, of interstellar voyaging. I think thats a smart approach. Its a mind-boggling thing to imagine, but so was going to the moon 100 years ago.

I think its a very good idea to start thinking about it now, and to spend a century thinking about the genetics, the cultural implications, the propulsion and designs. I think its possible, but I think it should be done carefully. I dont want to see a brief flurry of interest and then see it flare outthe American moon program did that.

One of your first projects in this field was to research the population genetics of a space colonization journey. What did you learn? If youre going on multigenerational voyages and you have a closed population, you dont have the natural interbreeding links that all human societies have. We have good evidence that human populations need to be well over 5,000 and into the tens of thousands of people to maintain healthy genetic variability. I suggested recently in a paper that 40,000 is a safe number.

People have proposed that you could send fewer human beings and store frozen eggs and sperm and maintain viability that way. But there are cultural reasons why thats not so great. I think we should go in populations that are culturally familiar. In evolution, generally speaking, radical changes in the short term are not too typically likely to work. And so I would propose a larger starship with tens of thousands of people aboard and let them sort out the new variety of social and genetic interactions that need to happen as theyre going. Dont try to invent it all here.

What are the other human evolutionary challenges associated with such a voyage? Its largely going to be developmental genetics in non-Earth environments. When we think of space biology now, we tend to think of adults. But Im thinking about the developmental biology of the young.

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Watch Live Tonight: The Challenges of Interstellar Flight