Book SummaryBecoming Martian, by Scott Solomon

1-Page Summary1-Page Book Summary of Becoming Martian

Plans for a human settlement on Mars are more serious than most people realize. Scientists have developed blueprints for propelling rockets on the monthslong journey from Earth to Mars, housing people on the red planet, and growing food on its lifeless surface. Little of this planning touches a question that fascinates evolutionary biologist Scott Solomon: What would life on Mars do to the people there? In Becoming Martian (2026), Solomon argues that Mars’s low gravity, intense radiation, and microbial isolation would make evolutionary change to the human species inevitable. Mars settlers will evolve into something different from the humans who first leave the Earth behind—so different they might cease to belong to the same species.

Solomon is a professor at Rice University and a research associate at the Smithsonian Institution’s National Museum of Natural History. In Future Humans (2016), he examined the evidence that humans are still evolving. From that exploration, a new question emerges: If natural selection can still shape us, what would happen to people who move to an environment more hostile than anything our species has ever seen? Solomon interviewed scientists in...

Becoming Martian Summary What Would Mars Make of Us?

Before asking how Mars would change us over evolutionary time, Solomon asks something more immediate: What will Mars do to anyone who lands there? This section examines the planet’s basic conditions, how space travel affects the human body and mind, and what Solomon contends is the single most important gap in our current knowledge—whether humans can reproduce on Mars.

What It’s Like on Mars

The Mars of popular imagination is a harsh but manageable environment: a blank slate for human colonization. In reality, the planet is inhospitable in ways that would prove enormously consequential for anyone trying to live there. Solomon reports that three conditions define the challenge. First, the gravity on Mars equals only 38% of Earth’s—if you weigh 100 pounds on Earth, you would weigh only 38 pounds on Mars. This difference would impact almost every system in the human body, from the bones that bear our weight to the heart that pumps blood against gravity’s pull. Research shows that even small decreases in gravity quickly cause many changes in the body, and these effects would compound over generations.

The Gravity Gap: What We Know and What We Don't

Gravity works...

Becoming Martian Summary Why Evolutionary Change Is Inevitable

The conditions on Mars wouldn’t just make life difficult for the first generation of Mars settlers. Solomon contends that the conditions in a Mars settlement would set evolutionary forces in motion that could transform the humans living there into something new over the span of generations. In this section, we’ll begin with the basic mechanisms of evolution, then examine the specific biological changes that scientists think the Martian environment would drive, and finally trace the force that Solomon argues would push Earth and Mars populations past the threshold of speciation.

The Mechanics of Evolutionary Change

We often imagine evolution as something that happened to our ancestors a long time ago, but Solomon writes that biologists understand evolution as an ongoing change in the inherited traits of a population across generations. All evolution requires is that some individuals in a population survive and reproduce more successfully than others, and that they pass those advantages on to their offspring. In this sense, evolution is happening right now to every population of organisms (including humans), and biologists recognize several distinct mechanisms by...

Becoming Martian Summary How Can We Take Control — And Should We?

Solomon argues that evolutionary change in humans living on Mars will be inevitable—but it might not need to be entirely unguided. For decades, scientists have been developing tools to deliberately edit human DNA, raising the possibility that future space settlers could be biologically prepared for the conditions they’ll face before they arrive. This section examines what those tools could do, the ethical questions they raise, and the paradox that Solomon sees haunting the project: that whether humans on Mars change through natural evolution or deliberate engineering, the result may be the same.

What Genetic Engineering Could Do

Natural evolution works, but at a cost. It produces adaptation through survival and reproduction, meaning generations of suffering and death take place before beneficial changes spread through a population. Genetic engineering offers the ability to equip people for an alien environment rather than waiting for the environment to select among them. The most significant tool available is CRISPR, a molecular editing system that can locate a specific sequence in the genome, cut the DNA there, and disable a gene or insert a new one. Scientists...

Shortform Exercise: What If You Were a Martian Colonist?

Solomon’s predictions describe what life would be like for people born into a Martian settlement, whose bodies would be shaped by conditions very different from anything humans have ever experienced. Over enough generations, biological differences would make them a whole new species.

If you’d been born and raised on Mars, would you want to try to visit Earth? What would you need to know or consider before deciding?

Shortform Exercise: Think About What We Owe to the Future

Solomon points out that the people most affected by the decision to settle Mars would be those with no say in making it. Children born on Mars would inherit bodies and circumstances shaped by decisions made before they existed: about where to live, whether to use genetic engineering, and how much contact to maintain with Earth.

Solomon distinguishes between adults who choose to accept the risks of going to Mars and children who would be born into those conditions. Do you find this distinction morally significant? Where would you draw a line between acceptable risk and unacceptable imposition?