Space.com reports that a recent study published in Scientific America suggests that human evolution will continue on multi-generation star ships that would travel to other star systems on voyages lasting for perhaps hundreds of years.
The environment of multi-generation star ship would influence evolution
Cameron Smith of Portland State University suggests that "new pressure, breathing-gas compositions, gravity and radiation environments will act on the early stages of embryo and fetus development," according to Space.com. This in turn would act as a natural selection mechanism, the effects of which are hard to predict.
Multi-generation ships as a way to colonize the stars
Unless some way is found to develop practicable warp drive, as NASA is working on, the only way to establish colonies on Earth-like worlds orbiting other stars would be to launch large, multi-generation ships that would travel below the speed of light. In effect these ships, worlds in miniature, would voyage for centuries, with children being born, growing up, having their own children, and then dying knowing only the ship. Eventually the ship would arrive at the destination and the generation then alive would leave and colonize the new world.
A study posted on the Starship Engineer website suggested an initial population of the generational ship of 500,000, with room to double that population to 1 million by the time the ship arrives at its destination. Smith suggests, though, that a population of about 2,000 would suffice to maintain a genetic diversity.
Guiding evolution on a multi-generation ship
According to Space.com, Smith suggests that the initial crew of the generation ship should be carefully screened as much as possible to avoid people with genetic predisposition for health problems. However, genetic diversity is essential as well in order to develop a viable population. The population would not only have to survive a possible pandemic but will have to be able to adapt to an alien environment once the new world is reached.
Cultural and technology changes also will be present
Space.com also reports that Smith believes that the population of a multi-generation ship will undergo cultural changes, due to their environment and isolation from Earth. These changes too will be hard to predict. It is possible that the society that arrives at the new world will have different values than the one that set forth from Earth. A population of highly intelligent, highly motivated space colonists will also advance the state of their technology during the long trip to a new world beyond the stars.
Mark R. Whittington is the author of Children of Apollo and The Last Moonwalker. He has written on space subjects for a variety of periodicals, including The Houston Chronicle, The Washington Post, USA Today, the L.A. Times, and The Weekly Standard.
- Cameron Smith