Brace yourselves, Battlestar fans: in real life Starbuck would probably be ugly as sin. Think more like a Ferengi, less like a supermodel. So would anyone else from the 12 Colonies, most likely. That's the implication of a new study of evolution here on Earth, which shows that natural selection can work at break-neck speeds.
Writing in Proceedings of the National Academy of Sciences, researchers described how an identical population of Podarcis sicula lizards was split up across two separate islands — one was the original habitat — in the Adriatic Sea in 1971. When the researchers returned to the islands 36 years later, the lizards on the foreign island had bigger, wider heads, stronger bites, and had evolved a bizarre new set of muscles in the digestive tracts.
Obviously it would take a little longer for people. On average, a human generation lasts about 30 years, and in the lizard experiment the recorded changes happened over 30 generations. That means even here on Earth you might only have to go back to medieval times to find ancestors that were lot different-looking than us (not counting the effects major improvements in medicine, technology, and nutrition, have had on our bodies).
But back to the 12 Colonies example. Even assuming every civilization progresses at roughly the same rate, the PNAS paper says habitat and diet (which are almost certainly going to be different from planet to planet) played the biggest part in shaping the lizards. In that case, thousands of years (millions?) of isolation between the Capricans, Aerelons, Gemenons, and so on would make for some truly bizarre humanoid morphologies. But then again, they'd probably think we we're pretty ugly, too.
Source: PNAS, via Living the Scientist Life