Will humans continue to evolve during multigenerational space missions?

Scientific American has posted an interview and podcast with Portland State University anthropologist Cameron Smith about the ways in which humans might evolve during extended missions in space. Given the intense timeframes involved, Smith speculates about the various ways in which Darwinian pressures will continue to shape human evolution. Just because we're in space, he argues, doesn't mean evolution has stopped. But while Smith is right about our need to adapt to space, his vision of how it will come about is utterly wrong — and here's why.

Top image courtesy Alexander Preuss, CG Society.

Smith, the author of Emigrating Beyond Earth: Human Adaptation and Space Colonization, is interested in the long-term human future and the ways in which interstellar colonization will forever alter the fabric of humanity — both culturally and biologically.

"So far the experience of humanity in space has been very limited," he told SciAm. "We have gone up for short periods of time, we've gone in very small numbers."

But as space access becomes cheaper and more people start going up, he says, we'll eventually have communities up there. "And then...our understanding of that is going to have to shift from purely biology to anthropology," he says. "These will be communities of people, and of course communities are cultural and they're also biological. So anthropology marries culture and biology. And it will be used to help us plan out successful space colonization."

Responding to a question about how people will change during a multigenerational mission, Smith had this to say:

Well, we can only predict that change will occur. We can make some predictions about some very few biological changes that might occur. But because mutation is random, and mutation is the origin of new characteristics in populations, because that is ultimately random, it's not entirely possible to say precisely what will happen. What we can say, though, is that new environments — for example, new radiation environments, whatever the gas composition is that people are breathing, whatever is the gravity field inside this starship — those basic environmental conditions will reshape the human genome. Subtly, subtly, but they will reshape it.

We know that we have evolved under almost 15 pounds of pressure per square inch at sea level. And in the last few thousand years, though, some people have migrated to higher elevations, where they are under somewhat less pressure. Their biology has changed to account for that, or to make it possible to live there. They have different blood oxygen levels, they have deeper chests with greater what is called lung ventilation, greater capacity for breathing in and taking in oxygen. And even the biology of the developing infant is somewhat different. And I am certain that exactly the same sort of thing, on that same magnitude, will happen in off-Earth environments.

Astoundingly, Smith also contends that biological evolution will result in an increase in infant mortality — what will put Darwinian selectional processes into play ('survival of the fittest,' here we come!). In addition, we will continue to deal with "ethnic rivalries" and "religious issues."

The fundamental problem with Smith's argument is his assumption that natural selection will continue to apply during extended missions in space. While he's right by suggesting that we'll have to adapt to our new environments (whether they be in space or on a new planet), he's completely wrong about the mechanism that will bring this about. It won't be Darwinian selection that will cause these changes, but rather the deliberate application of human biotechnologies instead.

Indeed, the idea of sending unmodified biological humans on interstellar missions is completely facile. We've known since the 1950s that space is no place for humans, and that the only way we'll ever be able to survive up there will be through radical morphological modifications. The entire field of cybernetics was predicated on this underlying assumption — and nothing has changed in the 60 years following its advent.

Moreover, Darwinian selection is slowly but surely being decommissioned, replaced by intentional design. In addition to cybernetics, we will modify ourselves and adapt to our environments by using advanced genomics, synthetic biology, and nanotechnology. And should we encounter any problems — which we surely will — we can use these same technologies to adapt on the fly.

As we wrote earlier this year:

Will humans continue to evolve during multigenerational space missions?S

Nanotechnology expert Robert Freitas has outlined a plan for the elimination of lungs, making breathable air unnecessary. Ray Kurzweil has speculated that future humans won't require food, equipped instead with nanobots that can energize our cells. And even Craig Venter has chimed in, putting out the call to develop an advanced inner ear that can allow people to escape motion sickness, genes for bone regeneration, and DNA repair for radiation He's also suggested that we develop a small stature, higher energy utilization, hairlessness, and slower skin turnover. And yet others have speculated about transforming humans into gangly octopus-like creatures who would be far more adapted to slithering around in zero gravity environments.

But relying on "random mutations," as Smith suggests, is completely ludicrous. We will be the ones in control of our genome, and not the whims of Darwinian processes. Our ability to live and work in space will not be a subtle thing, and not something that will come about after tens of thousands of years of agonizingly slow evolution.

Thinking even more conceptually, there's even the possibility that we'll have to become completely postbiological to survive long-term in space. This could entail our complete transformation into cyborgs, or as Giulio Prisco recently argued, as uploaded entities.

Either way, the future of humanity is a far cry from what Cameron Smith envisages.