The forces of evolution have shaped every living organism on Earth to adapt to their environment. Indeed, the most adaptable are the ones that have been able to survive and thrive on our planet. But if we go off planet how would we change? It's only natural to wonder what future humans born and bred on Mars will be like.
Scott Solomon, an evolutionary biology professor at Rice University, talked about this in a TEDx lecture at the University of Houston, Texas last year, and, more recently, did an interview with Inverse about it. He believes that the offspring of the first Martian settlers may have certain adaptations that Earthling humans do not have.
Mars is not a hospitable place, and certainly isn't a place that we could pretend is just like home. The Red Planet has about one-third of Earth’s gravity, which means you can jump higher and lift heavier weights, but your bones would also become more brittle, which is an extra complication for women, who already experience calcium depletion in pregnancy and menopause. Pregnancy itself would also be more difficult and dangerous. However, an adaptation might come in the form of denser bones, which would counteract the low gravity effect.
“Evolution is faster or slower depending on how much of an advantage there is to having a certain mutation,” Solomon told Inverse. “If a mutation pops up for people living on Mars, and it gives them a 50-percent survival advantage, that’s a huge advantage, right? And that means that those individuals are going to be passing those genes on at a much higher rate than they otherwise would have.”
Another issue is radiation. Mars hasn’t got a protective magnetic field like Earth, so a person on its surface would experience about 500 millisieverts every year, about 10 times the radiation limit the Environmental Protection Agency set for people working in nuclear power plants, and two to three times what astronauts experience on the International Space Station (ISS).
The increase in radiation will certainly affect the rate of mutation in Martian humans' DNA. Some mutations might lead to new adaptations, but the vast majority will certainly also increase the rate of cancers and leukemia. A possible adaptation to combat the higher radiation is developing new skin tones. Humans use melanin, which gives us the dark pigment in our hair and skin, to fight ultraviolet light from the Sun. Other species use carotenoids. Human from Mars might have completely different compounds.
The obvious way to mitigate radiation, though, is to build bases underground, where the soil can act as a shield. This could lead to other adaptation. Some research shows that constantly being indoors contributes to becoming myopic (near-sighted). Living underground could mean the condition might become the norm in the people of Mars.
Their evolution might also be shaped by something we don’t want to bring with us from Earth: microbes. While no spaceship is sterile (the ISS is full of microorganisms), it might be possible to significantly reduce the types of microbes we take to Mars and their danger to us. This, however, may lead to a weakening of the immune system.
If this were the case then the contact between Earthlings and Martians would have to be strictly controlled (no holiday flings here). People from our pale blue dot could unknowingly spread harmless infections that become deadly on the Red Planet.
Despite plans for imminent Mars missions and colonies, nothing concrete has yet been presented to map a future beyond Earth, so we’ll have plenty of time to wait and see if Solomons's theories of potential adaptations actually turn out to be true.