Okay but why does every pirate in space look ten times hotter than anyone back on Earth? Is this like... a universal law?
Let us assume patterns continue over time: All relationships begin with attraction, more attractive people have more chances to breed. Physical appearances are the simplest means by which to judge and or initiate relationships, other factors being legitimate outliers: No one chooses the Fat Ugly Basterd, regardless of his other traits, he is both fat and ugly.
Metabolisms are now higher on average than they were 600 years ago, as the ever increasing ease of access to food means that people with lower metabolisms end up with weight issues, and that is typically unattractive.
Space is a legitimate nightmare for biology, unless you meet or beat certain standards, your body will fail very quickly.
We have scientifically identified why certain facial and physical traits are considered attractive, the percentage of people with these traits is expected to continue to increase, these traits may vary by geographic ancestry; see also: Gradual Decline of Human Intelligence, Corresponding Improvement in Human Appearance.
Attractive People have more attractive children, typically.
Most space based scenarios or stories are placed in the future, people on space missions are expected to attract media attention, and their aesthetics will be considered.
Pretty and fit people tend to couple, making those more qualified for space a higher typical percentage in both fitness and appearance.
Uglier criminals get worse sentencing.
Taking these points: what is your conclusion, and does this satisfy your curiosity?
