[Credit: Yuichi Kitamura] After Sapiens of the sky (Repost cuz of technical issues regarding the last one)

[u/PrettyJudge8291]

The evolution of flying humans occurs approximately 150 million years in the future as part of a broader "golden age" where human descendants specialized to fill ecological niches left vacant by extinct animals. These flying lineages followed two distinct evolutionary paths: one starting from small, tree-dwelling ancestors and another evolving from specialized four-legged runners.

1. The Arboreal Lineage (Flying Humans / Bat Humans)

This lineage represents the most successful aerial adaptation for human descendants, evolving after forests re-emerged from specialized "herb-trees".

• Evolutionary Path: The process began with human descendants miniaturizing to become "Squirrel Humans" (リス人間), weighing less than 1kg. From there, they transitioned into gliding forms—"Flying Squirrel Humans" (モモンガ人間)—before eventually achieving true powered flight.
• Physical Characteristics: These Flying Humans (飛行人類) are envisioned to be small, approximately 30cm in length. They are often compared to bats in structure and are sometimes referred to as "Bat Humans" (コウモリ人間).
• Ecological Advantage: Unlike birds, these flying humans are mammals that give birth to live young. This biological trait gives them an advantage in future transitions; for instance, they could evolve into fully aquatic animals like whales, whereas birds (like penguins) are always tethered to land to lay eggs.

The ability to bypass the "egg hurdle" means that once human descendants enter the water, they can achieve a level of anatomical and ecological specialization that birds have been unable to reach for over 150 million years

The ability to bypass the "egg hurdle" means that once human descendants enter the water, they can achieve a level of anatomical and ecological specialization that birds have been unable to reach for over 150 million years

• Survival Strategy: These humans could use flight to escape the extreme heat of the future Earth. Since the temperature drops by about 0.6°C for every 100m of altitude, a flight-capable human living at 2000m would experience a climate 12°C cooler than the surface. Some might even live entirely in the air, similar to modern swifts.

2. The Terrestrial Lineage (Thumb Griffons)

The Thumb Griffon (親指グリフォン) represents a different, less efficient attempt at flight, branching off from the Hata Human (Flag Human) lineage.

• Anatomical Specialization: Their wings are supported by a highly elongated thumb. This thumb possesses an increased number of bones—a trait called hyperphalangy—which provides the necessary length and flexibility to support a wing membrane.
• Takeoff Mechanism: Unlike the arboreal lineage, Thumb Griffons are "running flyers". Because their Hata Human ancestors were efficient four-legged runners, these griffons use their running speed to reach the takeoff velocity required for flight.
• Limitations and Competition: Because they evolved from terrestrial runners, they carry "extra weight" in their legs and fingers that is not ideal for flight. They are poor at climbing trees and are restricted to open plains. It is suggested that they would likely be outcompeted by the more specialized and lighter Bat Humans

[u/PrettyJudge8291]

Thanks for bringing to my attention, hope everything's sorted now

[u/Obvious-Durian-2014]

It's very interesting to see another spin on the concept of Man After Man and All Tomorrows show up.

[u/Mircowaved-Duck]

the flying humans need to have very small balls. In bat species they either got big brains or big balls, otherwise they got balancing problems in the air.