A Note on Interstellar Migration

From my guest blog at Paul Gilster's influential 'Centauri Dreams' website, concerning interstellar migration. Sound crazy? SCIENCE magazine's recent edition focuses on exoplanets, now being discovered monthly, highlighting 'habitability'. Why highlight habitability? Because those are the places we humans are going if we don't wipe ourselves out first. Today Earth had its 'hair parted' by a space rock that could have wiped out civilization had it struck our planet--and in galactic terms, it came close.

"Over the course of several generations, as on voyages to nearby stars with propulsion systems that are beginning to seem reasonable, interstellar voyaging is entirely possible from a genetic perspective, with two provisions. First, we will have to ensure the genetic health of the colonist population as it will be under strong founder effect. Gene therapies, carrying genes from Earth in the form of stored eggs and sperm, and even the artificial induction of mutations can all be used to mitigate such effects, but at some point it will cease to be desirable to keep ‘pushing’ a human Earth genome into interstellar space. This brings us to the second proviso, and that is that natural selection will in fact return as a significant concern in human evolution, particularly when the unknowns of new planetary environments are encountered (even if they are surveyed by reconnaissance vehicles first).

We should note that, in the currently-considered timelines and populations, according to what we know about human biology it is unlikely that humanity will undergo speciation in less than a few thousand years (Figure 1, lower right).

These lessons remind us that adaptation is a continual process of the adjustment of the genome to environmental conditions. In non-humans that evolve reactively, with no conscious effort, this equilibriating process is slow and uncentralized and results in many extinctions over time. In humanity, consciousness can be used to help proactively shape our evolution, but we must remember that the only way to stop evolution is by extinction. We should accept and learn from the fact that if things live, they evolve and adapt. We should plan our adaptation to space as students of evolution. We must internalize the truth that the nature of the universe is change, not fixity, and allow this truth to condition our plans for the human colonization of space."