How Living on Mars Could Radically Change the Human Body
The ambition to establish human settlements on Mars is gaining momentum, but a growing body of scientific research suggests that living on the Red Planet could fundamentally alter humanity – not just culturally, but biologically. Rice University biologist Scott Solomon details these potential transformations in his forthcoming book, “Becoming Martian: How Living in Space Will Change Our Bodies and Minds,” scheduled for release in 2026.
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 a long evolutionary history on this planet.
Permanent life on Mars, however, would initiate a different evolutionary path. Martian colonists would face approximately 38% of Earth’s gravity, increased exposure to radiation, and a limited microbial ecosystem impacting human immune systems. These conditions, Solomon contends, could drive transformative changes across generations.
“Animals on islands often become larger or smaller over time,” Solomon told IFLScience, as reported by RealClearScience. “There’s a possibility that could happen to us.” He suggests that limited resources in a Martian settlement could favor individuals with smaller physiques, requiring less water, food, air, and space.
Reduced gravity poses significant physiological challenges. Experiments aboard the International Space Station have demonstrated that microgravity leads to bone density loss and muscle atrophy. Similar effects are anticipated on Mars, potentially resulting in a population with weaker bones and reduced muscle mass. Solomon warns that these effects could be particularly detrimental to children developing in a low-gravity environment. “If you’re building your skeleton and muscles in a low-gravity environment, there’s a great chance your skeleton and muscles won’t develop properly,” he noted.
Even the process of childbirth could be fundamentally altered. Solomon posits that the majority of births on Mars would likely require Cesarean sections. This shift could reshape the human species over time. “This creates an interesting 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 then there was an upper limit to how big the head could grow 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.
Visible changes to skin pigmentation are also probable. Melanin, the pigment in skin, provides protection against UV radiation. Mars lacks a substantial magnetic field and has a thin atmosphere, resulting in significantly higher radiation levels than Earth. “One scenario is that pigment evolves to make us darker, or a new pigment emerges that changes skin color. If you want to think about how we might look like science fiction aliens, there are some plausible scenarios,” Solomon stated.
The threat posed by microbes is often overlooked, Solomon argues. Astronauts in space experience weakened immune systems, and the bacteria that accompany them evolve and adapt to infect hosts in a foreign environment. Children born off-Earth would develop immune systems in almost complete isolation from microbes, exposed to only a fraction of the diversity naturally encountered on Earth. This could leave them particularly vulnerable to illness upon returning to Earth, or encountering new microbes on Mars.
Solomon believes this challenge is underestimated and could determine whether humans can freely travel between planets. He concludes that humanity is not yet prepared for off-world settlement. “I’m not saying we shouldn’t go. In fact, I think there are good reasons to endeavor eventually, but I don’t think we’re ready,” Solomon assessed.