Immediately the first thing to came to my mind was Gurren Lagann, because it's the main thing I've been obsessing over for the past few months. However, I'd like to think I'm creative enough to come up with my own scenario instead of stealing someone else's, so I won't use Gurren Lagann in my project.
But for practice, I tried coming up with what humanity would look like if Gurren Lagann was more realistic.
Possible physical changes resulted by living in small separate underground villages for one thousand years:
-Eventual inbreeding -> Homogeneous societies
-Increased nocturnal vision
-Short lifespans due to lack of nutrition and unbalanced diets as well as poor living conditions
-Loss of melanin in skin due to lack of exposure to sunlight -> lack of skin pigmentation
(Upon reaching the surface, skin cancer becomes common due to lack of protection against ultraviolet radiation from the sun)
Also taking into account that different villages have different levels of technology and food resources, different cultural customs among the villages will also appear.
-Jiiha Village has electricity, relies mainly on pigmoles for food, and has a water reservoir; no literacy
-Adai Village has no electricity, has a small lake which is their only source of food and water; no literacy; can only sustain 50 people at a time; develops strict religious customs to cope
-Bachika Village had oil, and developed an advanced society thanks to this natural resource; however, this also drew the attention of beastmen and the village was wiped out with only a few survivors remaining on the surface
-Ritona Village has electricity and weapons stores; retains literacy and written records of the past; is under constant attack by beastmen
Focusing only on Jiiha Village, the traits most sought after to survive would be ones centered on:
-Taking care of pigmoles (most valuable resource)
-Digging (to expand the living space)
As the best digger in his village, Simon would be the most fit to survive.
This is probably what he'd look like:
Uhhh yeah. Now to come up with my own scenario.
EDIT: Still on the topic of Gurren Lagann and Anthropology, back when the show was still airing, I secretly kept thinking how much its themes went against the stuff I was learning in Human Adaptation. You know, "the human shape is the best" and "evolution = progress" and stuff. But then the topic of the Spiral Nemesis came up, and then the last episode....and I thought, Wow...this is just like what I've been reading in Ishmael.
EDIT 2: Posted on /a/ for the lulz.