National / Science & Health | NATURAL SELECTIONS

Space exploration and human evolution

by Rowan Hooper

Special To The Japan Times

Can we become a multiplanetary species? There have been several spectacular announcements along these lines recently. Both SpaceX founder Elon Musk and Amazon founder Jeff Bezos have unveiled ambitious plans and tested rockets. Now aerospace multinational Boeing has ramped up its plans to get to Mars. What we’re doing is more than just becoming multiplanetary, however — we are intervening in human evolution. In short, we are accelerating our own speciation.

Some might look at what we’re doing to the Earth and suggest that the human “infection” shouldn’t be allowed to spread in the cosmos. Others, and it’s the majority view, held by people such as the physicist Stephen Hawking, say it’s the only way to ensure the long-term survival of our species. Whichever view you subscribe to, there is a new space race in operation.

Musk and Bezos are developing rockets — the Falcon Heavy and Blue Origin, respectively — to transport people to Mars. Boeing CEO Dennis Muilenburg announced that he wants his company to be the first to get to the red planet. He has a contract with NASA to transport U.S. astronauts to the International Space Station, as has Musk. But Muilenburg is very serious about Mars. “I’m convinced that the first person to step foot on Mars will arrive there riding on a Boeing rocket,” he said in Chicago last week.

Boeing has the advantage of collaboration with NASA. Boeing’s rocket is called the Space Launch System that, incidentally, is powered by RS-25 engines, a model that was used on space shuttles, and has since been refitted and re-tested.

SpaceX’s Falcon Heavy rocket is also an impressive beast. It is due to make its first test flight later this year, and when it does it will be the biggest operational rocket in the world by a factor of two. Its design is impressive; it’s big enough to carry more than 54 tons of payload into orbit. That, SpaceX says, is equivalent to an entire 737 jet loaded with passengers, crew, luggage and fuel. SpaceX also has plans for their Interplanetary Transport System — a commercial passenger rocket big enough for 100 people. Musk’s timeline is ambitious to say the least — he wants to launch the first people to Mars in 2024. Officially, NASA and Boeing are looking at a crewed flight to Mars in the 2030s.

I’ve mentioned some of the details of the rockets to emphasize that these projects are really happening. No doubt Musk’s dates will get pushed back as revisions delay launches. However, if he can secure the additional investment, he will probably be able to get to Mars at some stage. At that point, we will be able to describe ourselves as a multiplanetary species.

However, what we’ve not been considering is that we’re hastening the evolution of our own species. If we manage to get to Mars, we won’t just be multiplanetary — we will be on the way to splitting our species in two. That’s because humans evolved on Earth and are just not up to space travel. We’ll need to engineer people to to help them adapt better.

Our most obvious weakness is our ability to handle radiation. Radiation mutates our DNA and makes us prone to cancer. It’s enough of a problem on Earth but in space, even on a relatively short six-month trip to Mars, travelers would be exposed to large doses of cosmic radiation, certainly more than the current NASA limits for astronauts on the ISS. Maybe, people say, we would be able to reach Mars but then die there of cancer.

Takekazu Kunieda at the University of Tokyo has a possible solution, although it may also be some years off. He works on tardigrades, microscopic animals with eight legs that are resistant to massive doses of radiation. Kunieda and colleagues last month published a paper in the journal Nature Communications showing that tardigrades have a “damage suppressor” protein, or Dsup for short, that shields their DNA from radiation damage.

Kunieda thinks it may be possible in the future to engineer space-traveling humans with the Dsup protein, thereby gaining tardigrade-level protection. He also identified other genes in the tardigrade genome that help protect the animals from DNA damage.

Now, as soon as you start engineering people with special genes, you are creating a barrier to breeding with unmodified people. Not necessarily a genetic barrier, not at first. Someone with just a few tweaked genes would still be able to breed with an unmodified human, but they probably wouldn’t want to, because their offspring would not be guaranteed to get the desired genes. In any case, space pioneers will only have themselves to breed with, so the choice will be restricted.

And so far I’ve just mentioned one trait: tardigrade-radiation protection. However, space travelers will ultimately need a whole suite of adjustments. The most immediate will be changes to muscles and bones to cope with living on a planet with lower gravity that Earth. The immune system will work differently in space, diets will be less diverse so microbiomes will be different and so on. Indeed, there are a number of “improvements” we could make.

The point is that we should remember that we’re talking about making a new human species. I don’t actually have a problem with that. It seems sensible and necessary if we are to give ourselves the best shot of surviving what will be extraordinarily tough new lives.

The first people to live on Mars will live every day in conditions that make surviving an Antarctic winter look simple. I hope we eventually become a multiplanetary species. It’s important, however, to remember that we will also be on the way to creating a new, space-faring species. Homo sapiens martianius, perhaps?

Rowan Hooper is the news editor of New Scientist magazine. The second volume of Natural Selections columns translated into Japanese is published by Shinchosha. The title is “Hito wa Ima mo Shinka Shiteru” (“The Evolving Human”). Follow Rowan on Twitter @rowhoop.