spent almost a year on the International Space Station<\/a>, from March 2015 to March 2016, scientists found that the shape of his eyeball had changed, including developing a thicker retinal nerve and folds in the choroid layer that surrounds the eye, affecting visual acuity.)<\/p>\nThe cardiovascular system weakens as well, because the heart no longer has to pump blood uphill in the same way. Fluids shift upward in the body. The human form, shaped by millions of years under Earth\u2019s gravity, begins to subtly come apart.<\/p>\n
But Solomon\u2019s real concern is not what happens to healthy adults on relatively short missions. \u201cThe bigger issue,\u201d he said, \u201cis what happens when those conditions shape bodies from birth.\u201d<\/p>\n
\u201cThe research suggests that people living in the extreme environment of Mars would gradually adapt through natural selection,\u201d Solomon said. \u201cSo both culturally and biologically, people living on Mars would eventually become Martians.\u201d Pictured: a rendering from NASA\u2019s 3D Printed Habitat Challenge. NASA\/ Zopherus<\/p>\n
Solomon estimates that after 10 or more generations, spanning roughly 250 years, the accumulated effects of isolation, selection and immune divergence could make the populations of Earth and Mars effectively incompatible. Pictured: a rendering from NASA\u2019s 3D Printed Habitat Challenge. NASA\/ Mars Incubator<\/p>\n
Bones, for example, do not simply thin in low gravity. They grow differently.<\/p>\n
\u201cAs a child\u2019s body is growing and developing in lower gravity,\u201d Solomon said, \u201ctheir bones might not form in the same way.\u201d <\/p>\n
The problem is not just weakness, but structure. Certain microscopic connections inside bone may never form without Earth\u2019s constant downward pull.<\/p>\n
\u201cThere\u2019s this possibility,\u201d he said, \u201cthat a child born in lower gravity wouldn\u2019t form a skeleton strong enough to support being able to come back to Earth.\u201d<\/p>\n
In other words, you may be stuck on Mars from the day you are born.<\/p>\n
The immune system presents an even deeper problem. On Earth, it\u2019s trained from infancy by constant exposure to a vast and chaotic ecosystem of microbes. Every breath, every touch, every meal helps teach the body what is dangerous and what\u2019s not. \u201cBut most microbes on Earth won\u2019t be on Mars,\u201d Solomon said. \u201cWe\u2019ll take some by accident or on purpose, but it\u2019ll be a tiny slice.\u201d<\/p>\n
After astronaut Scott Kelly spent almost a year on the International Space Station, from March 2015 to March 2016, scientists found that the shape of his eyeball had changed, including developing a thicker retinal nerve and folds in the choroid layer that surrounds the eye, affecting visual acuity. NASA<\/p>\n
It\u2019s quite possible a child born and raised on Mars \u201cwould get sick if they come back to Earth,\u201d he added, \u201cbecause they\u2019d have no prior exposure to the vast majority of microbes we breathe in every day.\u201d<\/p>\n
In theory, vaccines could help. In practice, the challenge is overwhelming.<\/p>\n
\u201cWe have so many different kinds of microorganisms on Earth,\u201d Solomon said. \u201cWe haven\u2019t even discovered all of them, much less developed vaccines for the wide range a person would encounter when they take their first deep breath of Earth air.<\/p>\n
\u201cI think it could be a showstopper,\u201d he added, \u201cin terms of our ability to return to Earth once we\u2019ve settled other worlds.\u201d<\/p>\n
Childbirth may be the most unsettling case of all. \u201cWe know very little about pregnancy and childbirth in lower gravity,\u201d Solomon said. \u201cWe do know bone density decreases in lower gravity.\u201d Over a lifetime, that includes the pelvis. Solomon suggests that C-sections could become the norm for many Martian pregnancies.<\/p>\n
Once that happens, evolution takes an unexpected turn. Natural selection no longer favors bodies shaped for unassisted birth. Over generations, larger heads and narrower birth canals become easier, not harder, to pass on. A population can slowly back itself into permanent dependence on surgery just to reproduce.<\/p>\n
SpaceX plans to one day ferry crew and cargo to Mars. AFP via Getty Images<\/p>\n
It\u2019s the kind of feedback loop that rarely appears in glossy visions of space colonization, but sits squarely in the wheelhouse of evolutionary biology.<\/p>\n
Taken together, these changes point toward a future in which people born on Mars are not just culturally different from Earthlings, but biologically distinct. Solomon estimates that after 10 or more generations, spanning roughly 250 years, the accumulated effects of isolation, selection and immune divergence could make the two populations effectively incompatible. Not through deliberate genetic engineering, but through the same slow, inevitable mechanisms that have shaped life on Earth for billions of years.<\/p>\n
We\u2019ve seen versions of this story before, on a much smaller scale. Darwin\u2019s finches in the Gal\u00e1pagos Islands split into distinct species after periods of isolation. Human populations that settled remote islands developed noticeable physical differences within centuries. Mars would impose far more
extreme separation and far stronger selective pressures.<\/p>\n
The changes would not stop at the level of the body. Solomon devotes much of the book to the psychological and social challenges of life on another world. \u201cBeing in an isolated environment is stressful,\u201d he said. \u201cBeing in a dangerous, extreme environment is stressful. Being stuck with a small
number of people for a prolonged period is socially stressful. All of those would be true for Mars.\u201d<\/p>\n
Even on the International Space Station, where Earth is only hours away, isolation and confinement take a toll. On Mars, rescue would not be a phone call away. \u201cMars is much further away,\u201d Solomon said. \u201cAt least six months with current rocket technology for a one-way trip.\u201d And because the planets align only periodically, \u201cthere\u2019s only a window about every two years when it\u2019s even possible to send people back and forth.<\/p>\n
Astronauts Gerald Carr and William Pogue tested the effects of weightlessness at the International Sapce Station back in 1973. NASA<\/p>\n
\u201cIf you have a medical emergency, you can only get back every now and then, and it\u2019ll take a long time. That knowledge is psychologically stressful.\u201d<\/p>\n
Researchers have tried to model these pressures through \u201canalog\u201d missions on Earth, from Antarctic stations to desert habitats to the famous Biosphere 2 experiment in the 1990s, where eight people sealed themselves inside a giant dome in Arizona for two years. The project became notorious for internal conflict, food shortages and falling oxygen levels. Help was only minutes away. Mars would be tens of millions of miles.<\/p>\n
\u201cThere\u2019s a whole community of analog astronauts, researchers and volunteers who simulate space missions here on Earth,\u201d Solomon said.<\/p>\n
He visited their conferences and facilities while researching the book and came away impressed by the effort \u2014\u00a0but skeptical that any simulation can fully capture the psychological weight of permanent separation from Earth.<\/p>\n
Plus: At what point do we stop being human?<\/p>\n
\u201cBecoming Martian\u201d is on sale now.<\/p>\n
Part of the answer, Solomon suggests, is cultural. After a few generations, people born on Mars would almost certainly think of themselves as Martians first, just as immigrants on Earth gradually come to identify with new homelands. But the deeper shift would be biological.<\/p>\n
\u201cThe research suggests that people living in the extreme environment of Mars would gradually adapt through natural selection,\u201d he said. \u201cSo both culturally and biologically, people living on Mars would eventually become Martians.\u201d<\/p>\n
That doesn\u2019t mean he thinks humans should stay home forever. He\u2019s enthusiastic about exploration and scientific expeditions. But after five years immersed in the research, he\u2019s come away convinced that permanent settlement raises questions we\u2019re not yet ready to answer.<\/p>\n
\u201cI\u2019m very excited about sending people to the moon and Mars on scientific missions,\u201d he said. \u201cBut what I came away with is recognition that we\u2019re not yet ready to settle them. There are unanswered questions that need to be answered before it would make sense.\u201d<\/p>\n
When asked what he\u2019d tell his own children if they wanted to move to Mars permanently, his answer is careful and revealing. He\u2019d encourage curiosity and discovery. But he\u2019d worry deeply about a one-way trip. Earth, he points out, is not just familiar. It is exquisitely tuned to our biology in ways we are
only beginning to understand.<\/p>\n
With enough money and engineering talent, the problem of getting to Mars looks increasingly solvable. The bigger question is whether we should stay, and what staying would do to us.<\/p>\n
Your great-great-grandchildren may well live on another planet. But if Solomon is right, they may not be coming back. And in time, they may not even want to.<\/p>\n","protected":false},"excerpt":{"rendered":"The idea of humans living on Mars is closer to reality than it\u2019s ever been. On Feb. 13,…\n","protected":false},"author":2,"featured_media":484929,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[48],"tags":[223,3631,196,7042,718,79,193,1513,172],"class_list":["post-484928","post","type-post","status-publish","format-standard","has-post-thumbnail","category-space","tag-books","tag-international-space-station","tag-mars","tag-moon","tag-nasa","tag-science","tag-space","tag-spacex","tag-tech"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts\/484928","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/comments?post=484928"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts\/484928\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/media\/484929"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/media?parent=484928"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/categories?post=484928"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/tags?post=484928"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}