Now, apply this to people living in some other unusual circumstance, like a planet with different gravity or air pressure.
Originally shared by Kam-Yung Soh
Fascinating adaptation. “Bajau divers been observed plunging more than 200 feet underwater, their only protection a pair of wooden goggles — a physiological marvel.
In 2015, Melissa Ilardo, then a graduate student in genetics at the University of Copenhagen, heard about the Bajau. She wondered if centuries of diving could have led to the evolution of traits that made the task easier for them.
“It seemed like the perfect opportunity for natural selection to act on a population,” said Dr. Ilardo.
[…]
When people plunge into water, they respond with the so-called diving reflex: the heart rate slows and blood vessels constrict as a way to shunt blood to vital organs. The spleen also contracts, squirting a supply of oxygen-rich red blood cells into the circulation.
[…]
When Dr. Ilardo compared scans from the two villages, she found a stark difference. The Bajau had spleens about 50 percent bigger on average than those of the Saluan.
Yet even such a remarkable difference might not be the result of evolution. Diving itself might somehow enlarge the spleen. There are plenty of examples of experience changing the body, from calloused feet to bulging biceps.
Only some Bajau are full-time divers. Others, such as teachers and shopkeepers, have never dived. But they, too, had large spleens, Dr. Ilardo found. It was likely the Bajau are born that way, thanks to their genes.”
https://www.nytimes.com/2018/04/19/science/bajau-evolution-ocean-diving.html
I read a book about evolution into non-Terrestrial humans many years ago; only bit I remember was chronic spacefarers selecting for stockiness, so they slowly evolved toward a sphere to minimise surface area.