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Sunday, Sept. 13, 2009

NATURAL SELECTIONS

Sex in space could be the key to the survival of humans


I've been thinking about sex in space. Not from any interest in a potential new porn genre, or because I've got a chance of joining the 62-mile-high club any time soon. No, my concerns are loftier even than that: I'm worried about the future of humanity.

As British physicist Stephen Hawking said in a talk to NASA last year: "Spreading out into space will completely change the future of the human race and maybe determine whether we have any future at all."

Hawking recommended that we get off-planet within the next 200-500 years to have any hope that the human species will survive long-term. That's not to say we shouldn't bother trying to protect Earth from the terrible devastation we are wreaking upon it — we should, and fast — but in the long term, most species go extinct. That's just the way it goes. To guarantee the survival of humanity, we need to colonize other planets.

And it's not a straightforward matter. Newton's third law gets in the way — that's the one that says every action has an equal and opposite reaction. Floating in microgravity might be fun, in other words, but it might make sex more tricky. And incidentally, the size of a man's penis is said to decrease slightly in microgravity due to the decrease in his blood pressure in space. But more serious is the fact that fertilization and embryo implantation has evolved here on Earth: Getting it to work in space is a major problem.

Several research projects are already underway to work out just how we will be able to reproduce in the special, unnatural conditions of space — and some of the projects are based in Japan.

Sayaka Wakayama at RIKEN's Laboratory for Genomic Reprogramming in Kobe is involved in one such project. Wakayama and colleagues are investigating how fertilization and embryo development occur in microgravity.

We already know that mammals have had sex in space — though we're talking rat sex, not people sex. (There are lots of rumors, especially about the Endeavour shuttle mission in 1992, on which a married couple flew, but NASA denies that any of its astronauts have had sex on a mission.)

In 1979, the Cosmos 1129 space mission, also known as Bion 5, was a joint collaboration between the United States and the Soviet Union. It was primarily a biomedical program, and on this particular mission male and female rats were sent into space and allowed to do what comes naturally.

Whatever problems there might be with having sex in microgravity, floating in space, the rats managed it. I'm not surprised really. If you've ever dissected a male rat in biology class you'll have noted the size of their testicles: I'm sure that given a sniff of a female, even a rat floating in orbit round our planet would try to get it on.

Two other species were on board Bion 5, by the way: the Japanese quail, and some carrots. But my concern here is with the rats. When they returned to Earth, the female rats were examined. Two had become pregnant, but they did not give birth. Apparently the space-embryos were reabsorbed.

Ever since then, an important question has remained unsolved: is it possible for mammals to reproduce in space, and if so, what are the particular concerns? It is this that Wakayama's team is investigating.

The researchers don't have to go into orbit to do their work. They put mouse sperm into a clinostat, a kind of gyroscopic spinning device that mimics the effects of weightlessness, and used the dizzy sperm to fertilize eggs. The eggs did start to develop, so fertilization itself wasn't prevented by microgravity. But many of the "space embryos" didn't develop properly, and only some led to normal pregnancy and birth.

"These results suggest for the first time that fertilization can occur normally under a microgravity environment in a mammal," Wakayama's team write, in the journal PLoS ONE, "but normal preimplantation embryo development might require 1G [full Earth-like gravity]".

Wakayama and her colleagues are continuing work that was carried out on board the space shuttle Columbia. Columbia is remembered primarily for the tragic accident that destroyed it with the loss of all seven crew members in 2003. But in late 1996 the shuttle took some very early-stage mouse embryos into space. They failed to properly develop, and it is this developmental problem that the Japanese team are working on.

"Sustaining life beyond Earth either on space stations or on other planets will require a clear understanding of how the space environment affects key phases of mammalian reproduction," write the researchers.

Eventually, in the centuries to come, we will no doubt exist in a form totally different to today. We will surely be massively modified — we might be part machine or we might eventually not bother to have organic bodies. But for the foreseeable future, at least, we'll need the tried and tested method of making new humans.

It's not many research groups who can say that they're working on something that is both out of this world, and which could be key to the survival of the human race.

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: How new biology explains your journey through life"); Price ¥1,500.

Follow Rowan Hooper on Twitter at twitter.com/rowanNS



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