Behold: the double-headed space worm

Not many humans have been into space, and in the greater scheme of things, not for very long spells either. The longest continuous spell spent in space is still 437 days – a record set by Valery Polyakov back in 1995 which is a long time, but nothing compared to our planned mission to Mars. It takes six months just to get there, after all, and you’d want some time to check out the sights, sparse as they may be.

The trouble is that from our admittedly small sample of astronauts that have gone into space, a worrying proportion of them have come back with health issues. Forget the bone deterioration and loss of eyesight: they seem to be four to five times more likely to die of cardiovascular disease. Sending more humans isn’t an option, so we send other life up on our behalf to see how they fare.

And in the case of one planarian flatworm, the answer is strangely. Really strangely.

In a study published in Regeneration, researchers found that one flatworm from a sample of 15 sent for an all-expenses-paid five week vacation aboard the International Space Station returned to Earth and promptly grew a second head. That’s something that the researchers haven’t seen in over 18 years spent examining tens of thousands of flatworms.

Flatworms are used for experiments because of their abilities to regenerate parts of their body after amputation, and this particular specimen had been amputated before it left our atmosphere. But the worms left in tact also behaved oddly, with some of them splitting into two or more unique worms. But that’s something the scientists think could be down to a change in temperature.

But back to our two-headed friend, because astonishingly you haven’t heard the weirdest bit yet. The researchers clearly didn’t consider it a friend in the way I just referred to it, as they amputated both its heads to see what would happen next. They grew back. Both of them. That’s really weird, because it suggests this isn’t just a mutation: its whole body has been reprogrammed and it now considers itself to be a two-headed species.

“As humans transition toward becoming a space-faring species, it is important that we deduce the impact of space flight on regenerative health for the sake of medicine and the future of space laboratory research,” sain Junji Morokuma, lead author of the study.

To be 100% clear, flatworms aren’t humans, and this isn’t likely to result in the doubling of NASA’s helmet budget. But it does show that when it comes to fully understanding the impact of space flight on the body, we have a whole lot left to learn.

Image: Junji Morokuma, Allen Discovery Center at Tufts University