Humans on Mars: The Future of Life Beyond Earth
The prospect of humans living on Mars is more tangible now than it has ever been.
On February 13, SpaceX, led by Elon Musk, sent an international team of four astronauts to the International Space Station, demonstrating that private companies can routinely launch people into orbit. The company is also continuing to refine its immense Starship rocket, which it envisions using for missions to the moon and possibly Mars one day.
Simultaneously, NASA is advancing its Artemis program, which aims to land astronauts on the moon again and utilize these missions as a stepping-stone for exploring deeper space. Mars continues to be a distant objective.
The discussions about humanity’s potential future on another planet range from tech moguls in Silicon Valley to casual fans of science fiction. Yet, a new book by evolutionary biologist Scott E. Solomon poses a more unsettling question: What might happen to humanity if we decide to remain on Earth?
In *Becoming Martian: How Living in Space Will Change Our Bodies and Minds*, Solomon suggests that future generations of astronauts may find themselves at odds with those who stay behind on Earth. He posits that these descendants might not be able to return home, and over many generations, they could evolve into a distinct species.
Solomon argues, “The colonization of other worlds will change the very definition of what it means to be human.”
Although not a rocket scientist, Solomon is a professor of ecology and evolutionary biology at Rice University and a research associate at the Smithsonian National Museum of Natural History. His career has revolved around studying how organisms adapt to new environments, including significant fieldwork in the Amazon rainforest.
After witnessing SpaceX’s first Starship launch in Texas—a launch that ended dramatically—he began considering the implications of Mars in earnest. Rather than focusing on the technical aspects of the launch, he found himself pondering deeper evolutionary questions about those who might leave Earth for other worlds.
When considering the impact of living in a low-gravity environment from birth, Solomon questions how our bodies will change over time. For instance, he notes that children born on Mars “are very likely to get sick when they return to Earth because they haven’t been pre-exposed to the many microbes we encounter daily.”
Solomon points out that the biological changes might not only affect adults but could also reshape the very foundation of humanity. He mentions how astronauts experience muscle weakening and changes in bone density due to the lack of gravity, but emphasizes that the long-term implications for those born in space could be more severe.
He raises concerns about developing immune systems: Earthlings are constantly exposed to a variety of microbes that help train our immune systems. “Most microbes found on Earth will not exist on Mars,” he asserts, which presents real challenges for any future Martians returning to Earth.
The hurdles don’t stop there. Solomon suggests that if women were to give birth on Mars, the lower gravity might lead to different physical challenges during pregnancy. For example, C-sections could become the norm as the physical shape required for natural births evolves with each generation.
In the book, Solomon argues that the cumulative effects of life on Mars could lead to two populations—Earthlings and Martians—becoming fundamentally incompatible over time due to natural selection.
He draws parallels to historical events like Darwin’s finches, which, after isolation, evolved into distinct species. Similarly, Mars could impose even stronger selective pressures on its inhabitants.
The shifts wouldn’t solely be physical; Solomon stresses that the psychological and social challenges of living on another planet are significant. Mars presents a much more extreme environment compared to the International Space Station, with longer wait times for rescue and care in emergencies. He reflects on past “analog” missions on Earth that attempted to simulate space conditions and recognizes that they often fell short of capturing the full weight of such isolation.
Ultimately, as life continues on Mars, those born there may begin to see themselves as Martians, much like previous immigrants have adapted to new homes. Yet, Solomon concludes that while he’s a strong advocate for exploration, we need to closely examine whether we are prepared for the consequences that come with permanent human residency on another planet.
So, when asked about his thoughts on his children living permanently on Mars, Solomon’s answer is cautious yet encouraging. He promotes curiosity and exploration, but acknowledges that the idea of leaving Earth—our finely-tuned home—comes with profound uncertainties.
With emerging technologies making the journey to Mars look feasible, the pressing question remains whether we should stay there long-term and what it would mean for our species. Future generations may indeed inhabit new worlds, but as Solomon warns, they may find it increasingly challenging to return home—if they wish to at all.
