Human evolution at the crossroads

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Astrans: Turning into an alien race
Image: Astran
Astran: Body hair just gets in the way during interstellar trips.
If humans survive long enough, there’s one sure way to grow new branches on our evolutionary family tree: by spreading out to other planets.

Habitable worlds beyond Earth could be a 23rd century analog to the Galapagos Islands, Charles Darwin’s evolutionary laboratory: just barely close enough for travelers to get to, but far enough away that there'd be little gene-mixing with the parent species.

“If we get off to the stars, then yes, we will have speciation,” said University of Washington paleontologist Peter Ward. “But can we ever get off the Earth?”

Currently, the closest star system thought to have a planet is Epsilon Eridani, 10.5 light-years away. Even if spaceships could travel at 1 percent the speed of light — an incredible 6.7 million mph — it would take more than a millennium to get there.

Even Mars might be far enough: If humans established a permanent settlement there, the radically different living conditions would change the evolutionary equation. For example, those who are born and raised in one-third of Earth’s gravity could never feel at home on the old “home planet.” It wouldn’t take long for the new Martians to become a breed apart.

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As for distant stars, the SETI Institute’s Seth Shostak has already been thinking through the possibilities:

Build a big ark: Build a spaceship big enough to carry an entire civilization to the destination star system. The problem is, that environment might be just too unnatural for natural humans. “If you talk to the sociologists, they’ll say that it will not work. … You’ll be lucky if anybody’s still alive after the third generation,” Shostak said.
Go to warp speed: Somehow we discover a wormhole or find a way to travel at relativistic speeds. “That sounds OK, except for the fact that nobody knows how to do it,” Shostak said.
Enter the Astrans: Humans are genetically engineered to tolerate ultra long-term hibernation aboard robotic ships. Once the ship reaches its destination, these “Astrans” are awakened to start the work of settling a new world. “That’s one possibility,” Shostak said.

The ultimate approach would be to send the instructions for making humans rather than the humans themselves, Shostak said.

“We’re not going to put anything in a rocket, we’re just going to beam ourselves to the stars,” he explained. “The only trouble is, if there’s nobody on the other end to put you back together, there’s no point.”

So are we back to square one? Not necessarily, Shostak said. Setting up the receivers on other stars is no job for a human, “but the machines could make it work.”

In fact, if any other society is significantly further along than ours, such a network might be up and running by now. “The machines really could develop large tracts of galactic real estate, whereas it’s really hard for biology to travel,” Shostak said.

It all seems inconceivable, but if humans really are extinction-proof — if they manage to survive global catastrophes, genetic upheavals and cybernetic challenges — who’s to say what will be inconceivable millions of years from now? Two intelligent species, human and machine, just might work together to spread life through the universe.

“If you were sufficiently motivated,” Shostak said, “you could in fact keep it going forever.”