Episode Title: Becoming Martian: What Space Will Do to the Human Body, Mind, and Species
Runtime: ~55 minutes
Episode Summary
What happens to us — biologically, genetically, evolutionarily — if humans actually go live on Mars? Not visit. Live. Dr. Scott Solomon, evolutionary biologist and teaching professor at Rice University, has spent years following that question to its surprisingly unsettling conclusions. His new book, Becoming Martian (MIT Press), argues that the most profound consequence of human space settlement won't be geopolitical or even scientific. It'll be biological. We will change. Possibly into something that can never come home.
This conversation ranges from ant colonies to CRISPR, from the Polynesian navigators to H.G. Wells — and lands on a question that is equal parts thrilling and sobering: are we ready?
About the Guest
Dr. Scott Solomon is a biologist and teaching professor at Rice University, a research associate at the Smithsonian Institution, and one of the most compelling science communicators working today. His writing has appeared in The Washington Post, National Geographic, and Wired. He has been featured on NPR, the BBC, and ABC News, and hosts the podcast Wild World with Scott Solomon.
Previous book: Future Humans (2016) — where is evolution taking us here on Earth?
New book: Becoming Martian (MIT Press, 2025) — how living in space will change our bodies and minds
What We Cover
The big-picture case for going
Why does Scott believe becoming a multiplanetary species isn't just appealing — it may be morally necessary? The "eggs in one planetary basket" argument, and why the cost of not going deserves more attention than it gets.
Genetics vs. epigenetics in space
What's the difference, and why does it matter for astronauts? Scott breaks it down clearly: genetic changes alter your DNA sequence permanently; epigenetic changes affect how genes switch on and off and can be reversed. The NASA Twin Study — Scott Kelly in space, his identical twin Mark on Earth — gave us our first real window into what spaceflight does at the molecular level.
Radiation: the uninvited passenger
Mars has no magnetosphere and almost no atmosphere. Space radiation hits the surface at nearly full strength. That causes mutations — and while most mutations are neutral or harmful, some, over generations, become the raw material for adaptation.
Can humans reproduce in space?
Surprisingly, we don't really know. Very few experiments have been done. What we do know raises serious questions about pregnancy, childbirth, and child development in low gravity — including the unsettling implications of weakened pelvic bones and an immune system that has never encountered Earth's microorganisms.
The Polynesian parallel
The ancient Polynesians were the greatest navigators in human history, finding and settling nearly every island in the Pacific. So why didn't they evolve into new human species? Scott explains what their story teaches us — and why Mars is different in the ways that matter most.
Who should go, and why it's not just about skills
Selecting the founding population for a Mars settlement isn't only about piloting ability or psychological resilience. Genetic diversity in the founding group could determine whether future generations can adapt and survive. The biology of the colonists matters as much as their résumés.
Could Martian-born humans ever return to Earth?
If future generations adapt to one-third gravity and a radically different microbial environment, coming back to Earth could be genuinely dangerous — structurally, cardiovascularly, and immunologically. A kind of reverse War of the Worlds scenario: not aliens bringing disease to Earth, but humans returning as immunological strangers to their home planet.
CRISPR and the ethics of deliberate adaptation
We have the technology to edit human DNA to make people better suited to Martian conditions. Should we? What do we lose if we do? Scott unpacks the ethical terrain with characteristic care.
Should we go at all?
Scott's honest conclusion: eventually, probably yes. But not yet. Too many foundational questions — about reproduction, about return, about the rights of whatever life might already be there — remain unanswered. Research, yes. Settlement, not quite yet.
Books & Resources
Becoming Martian by Scott Solomon (MIT Press, 2025)
Future Humans by Scott Solomon (2016)
Wild World with Scott Solomon — podcast
The NASA Twin Study (Scott Kelly / Mark Kelly)
Scott Solomon's work at Rice University
