The ambition to establish human settlements on Mars is gaining momentum, but a new analysis suggests that living on the Red Planet could fundamentally alter humans – and not just culturally or socially. A new book details how a Martian existence could trigger biological transformations in the human body.
Scott Solomon, an evolutionary biologist from Rice University, explores these potential impacts in his new book, “Becoming Martian: How Living in Space Will Change Our Bodies and Minds.” The work examines how adapting to a new world could reshape human physiology over generations.
Solomon argues that millions of years of evolution have shaped Homo sapiens to thrive on Earth. Our bodies and brains are adapted to the planet’s atmosphere, gravity, radiation levels, microbial environment, and light-dark cycles. From bone density to circadian rhythms, these are all products of long-term adaptation to Earth’s conditions.
Permanent life on Mars, although, would introduce a different evolutionary path. This shift has implications for the future of human adaptation and the challenges of interplanetary travel.
According to reporting from Detik iNET, Martian colonists would face approximately 38% of Earth’s gravity, increased radiation exposure, and a limited microbial ecosystem impacting human immune systems. These conditions would present significant, and potentially transformative, challenges across generations.
“Animals on islands often become larger or smaller over time. It’s possible that could happen to us,” Solomon told IFLScience.
He added that limited resources in a space settlement could favor smaller individuals, as they require less water, food, air, and space.
Weaker Bones
Low gravity could trigger serious physiological challenges. Experiments on the International Space Station have demonstrated that microgravity leads to bone density loss and muscle atrophy. Similar effects could occur on Mars, potentially resulting in a population with weaker bones and reduced muscle mass.
Solomon argues these effects could be particularly detrimental to children whose bodies are still developing. “If you’re building your skeleton and muscles in a low-gravity environment, there’s a good chance they won’t develop properly,” he noted.
Larger Heads
Childbirth also presents a significant issue. Solomon believes that most births on Mars would require Cesarean sections. This shift could reshape the human species over time.
“That creates an fascinating scenario where if all births are C-sections, then the head is no longer constrained by having to fit through the birth canal, which has been a constraint throughout human evolution. As our ancestors evolved, our brains got bigger and our heads got bigger, but there was an upper limit to how big the head could acquire because you still had to get the head through the birth canal. If that’s no longer the case, the head could evolve to be larger,” Solomon explained.
Changing Skin
Visible changes could also occur in skin pigmentation. Melanin, the pigment in skin, acts as a shield against UV radiation. Mars has a much higher radiation environment than Earth due to the lack of a magnetic field and a thin atmosphere.
“One scenario is that pigment evolves to make us darker, or a new pigment emerges that changes skin color. If you want to perceive about how we might look like science fiction aliens, there are some reasonable scenarios,” he said.
Increased Susceptibility to Illness
The threat of microbes is often overlooked, Solomon argues. Astronauts in space experience weakened immune systems. Bacteria traveling with them will also evolve and adapt to infect hosts in a foreign environment.
Children born off-Earth will develop immune systems in total microbial isolation, exposed to only a small fraction of the diversity they would naturally encounter on Earth. Return trips could leave them highly vulnerable to illness.
Solomon assesses that this challenge is underestimated and could determine whether humans can freely move between planets.
For these reasons, Solomon concludes that humanity is not yet ready to settle in space.
“I’m not saying we shouldn’t proceed. In fact, I think there are good reasons to try eventually, but I don’t think we’re ready,” Solomon concluded.
