Human are weird/space orcs: adaptability, size, and diet
All of these topics have been touched on by others more familiar with the humans-in-space musings, but I just wanted to expand on them because I think they're cool. Also, if anyone has done exactly this, let me know because I have not yet seen that post and would love to read it!!!
Adaptability:
Humans are extremely capable of consciously adapting to new environments, whether social or physical. We're social creatures and incredible vocal/body language mimics, so we can do pretty well in a variety of situations. But I'm specifically fascinated by subconcious, physical adaptation by the human body and mind.
On Earth, oxygen levels are noticeably different at different elevations. Humans live in environments so high into our atmosphere that even trees don't grow there. This doesn't cause genetic differences in different human populations, though (at least in regards to oxygen processing). Humans can literally just... move to a different elevation and adjust to a different oxygen level within in a matter of years. There are no negative side affects of this transition. Just a brief lapse or boost of physical capabilities.
There's also temperature acclimation. When people travel to vastly different climates than their home, they notice the difference. A lot. Where I live, a 45 degree (Fahrenheit) day in spring is tshirt weather. You can always pick out the tourists really easily because they're the ones wearing large jackets. There's also seasonal acclimation and long-term acclimation that happen in tandem, especially in areas with strong seasons, but that's a different post.
Don't even get me started on food (see the Diet section). Seafood, as much as I love it, turns my stomach. I can't handle a ton of spice because it wasn't really part of my diet growing up. Different cultures with different cuisines often have defining staples of their food that can upset the stomach of someone who doesn't eat it that often. But as long as the food is edible and the person eating it doesn't have a genuine allergy to it... it's food. And humans (and their gut biome bacteria) can adjust to almost any cuisine in the span of a single human lifetime, if not a decade or two.
Size:
Humans are omnivorous apex predators. Only other apex predators hunt us as a food source. I wonder how humans would compare to other space-faring apex predator species. One could easily make the argument that the caloric requirements for the brain to take a species to space would result in a similar evolutionary path to humans, but I think the chances of that being an unbroken rule are slim. I wonder if we'd be remarkably smaller to the other intelligent predator species we'd encounter in space. Humans survived an evolutionary gamble to devote about 30% of all caloric intake to having thoughts. Energy that could have been used for size, muscle, claws, teeth, etc, went instead to thinking about things. And it worked. We have none of the physical capabilities of your average apex predator. We can just run for really long periods of time and make/use tools. Which, as it turns out, is a killer combo. But would we be smaller, weaker, squishier than the other space-faring aliens like us? If a space community is segregated by food chain levels (kinda hard to sit next to someone in the cafeteria as they eat your neighbor, y'know?), would humans have to jump to reach the light switches and the counter? Would a group of humans have to split one standard food portion?
Diet:
This one is two-pronged; human diets, and human digestion. Humans can eat A Lot of Things. Root vegetables and miscellaneous vegetation, berries/fruits, meat, dairy, eggs, grain/seeds, living creatures (bacteria in yogurt and whatnot). You name it, we can probably eat it. Aliens that evolved to handle much narrower diets would be baffled by the range of food humans could eat.
I also think aliens would be thrown off by the fact that humans don't digest their own food. Our stomachs are essentially a giant holding tank for billions, if not trillions, of bacteria that break our food down into their base components, which we then absorb and use. As a result, the health of a human's gut biome and the bacteria present determines what a human can eat. Imagine, if you will, a human having to explain to an alien crewmate why they have to eat dairy regularly to maintain the ability to eat dairy.









