Friday, May 17, 2013

Interstellar Migrant Population

Did some adjustments (see previous post); all of this came out of looking at these figures from the perspective of early human migrations, researched for my forthcoming Atlas of Human Prehistory! But Icarus Interstellar asked me to juggle them for their purposes. This'll go to either Journal of the British Interplanetary Society or Acta Astronautica (International Academy of Astronautics) for peer review :p

Estimation of a Viable Population for Multigenerational Interstellar Voyages

Cameron M. Smith
Department of Anthropology
Portland State University
17 May 2013
7,243 words
Late Draft Form; some figures to be added, but essential findings are secure.


"Designing interstellar starships for human migration to exoplanets requires establishing the starship population, which determines many variables including overall design, architecture, mass and propulsion. I review the central issues of population genetics (effects of mutation, migration, selection and drift) and demographics (population size, age, and sex structure on departure) for human populations on such voyages, specifically referencing a roughly 5-generation (c.150-year) voyage currently in the realm of thought among the Icarus Interstellar research group. I present several formulae as well as concrete numbers that can be used to help determine populations that could survive such journeys in good health. I describe why previously-proposed multigenerational voyage populations, on the order of a few hundred individuals, are significantly too low to consider based on current understanding of human genetic variation and general patterns in vertebrate population dynamics. Population genetics theory, calculations and computer modeling determine that a properly-screened and age- and sex-structured total population (Nc) of anywhere from roughly 14,000 to 44,000 people would be entirely sufficient to survive such journeys in good health. A safe and well-considered figure is 40,000 people. This ‘IMP’ or Interstellar Migrant Population, would be composed of an effective population [Ne] of 23,400 reproductive males and females, the rest being pre- or post reproductive individuals. This number would maintain good health over five generations despite (a) increased inbreeding resulting from a relatively small human population, (b) depressed genetic diversity due to the founder effect, (c) demographic change through time and (d) expectation of at least one severe population catastrophe over the 5-generation voyage."

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