Hi there,

This week I've got two biomechanics stories that should make you smile. One is about a snake that moves like a cross between a hula hoop and a bullwhip. The other is about an ant that has changed the chemistry of its venom to make its stinger work like a glue gun. Man, those are great stories. Seriously.

Also this week, Japan has launched a spacecraft toward one of Mars' two moons – a tiny nothing of a rock, just 22 km across. The moon is so small, in fact, that it's hardly got enough gravity for a landing to happen at all. But the team behind the mission is optimistic, and I'll tell you why.

If that's not enough, I've got a social science story, too... about how just a handful of rule-breakers can push a community of rule-followers into anarchy. Oh, and I want to show you a tattoo, too. Don't worry. It's not on my butt. In fact, it's not on me, at all.

Let's get started, and we begin with the snake. Brace yourself. This is truly awesome.

Rolling is rare in the animal kingdom, mostly because spinning your body like a tire makes it hard to keep your sensory system oriented. But a group of tiny snakes in Borneo has found a workaround. New research shows that dwarf reed snakes (Pseudorabdion) roll away from danger like a wheel, reaching peak forward speeds of 1.7 to 3.7 metres per second (average 2.3 m/s), which is roughly four times faster than they slither. The reason it works for the snakes is that they’ve found a way to overcome the sensory issue; while the back half of the body is cartwheeling, the head stays facing forward, never flipping upside down. It’s kind of like how spinning ballerinas keep their focus in one direction, or how a running chicken keeps its head still most of the time, relative to the ground.

This video has been living rent-free in my brain since the first time I saw it. I can only hope it's just as impressive to you, too.

Japan has just launched a mission to land on the larger of Mars's two moons, scoop up a piece of it, and bring it home to Earth. The Martian Moons eXploration mission, or MMX, lifted off from Japan on Oct 19. It will spend about 10 months travelling to Mars, arriving next August.

The moon in question is just 22 km across, and is called Phobos. And the purpose behind the mission is to figure out the origin stories of Phobos and its smaller sibling, Deimos (diameter ~12 km). Both moons look like asteroids, so one hypothesis is that Mars captured them with its gravity billions of years ago. But other evidence suggests they're leftovers from a giant impact early in Mars's history, similar to the giant impact that caused Earth to have a moon. Telescopes and orbiters can't settle that debate from a distance, but a sample brought back to a lab would settle it very nicely, indeed.

Phobos is a tricky target, but Japan’s optimistic because they’re coming off a pair of robot asteroid visits that went beautifully, Hayabusa and Hayabusa 2. Phobos' gravity is far too weak, and Mars's gravity is too strong, for the spacecraft to orbit the moon, so MMX will have to manoeuvre around the moon while they orbit the planet together. Then, in late 2028 or early 2029, the spacecraft will drop a shoebox-sized four-wheeled rover called Idefix, built by the French and German space agencies. It will try to drive around for up to 100 days in gravity less than one-thousandth of Earth's. Later in 2029, the main spacecraft will make up to two landings, staying on the surface for several hours and collecting samples two ways: a coring drill on a robotic arm that pulls out a cigar-shaped specimen, and a NASA-provided pneumatic sampler that fires high-pressure nitrogen gas to sweep material into a canister. The samples head for Earth in 2030 and should land in South Australia in 2031.

As a bonus, Phobos flies about 6,000 km above the Martian surface – roughly 40 times closer to Mars than our Moon does to Earth, and closer than any other moon in the solar system to its planet. As a result, the haul might even include bits of Mars itself that have settled on the moon, a preview of what scientists hope to learn when they finally get samples from the Martian surface.

When people see a cheater cheat, it nudges them to cheat, too. But when people see others obey the rules, it doesn't really have any effect at all. As a result, a few bad apples can push an otherwise law-abiding population into a worse version of itself.

This conclusion comes from an experiment in which participants watched an animated shooting star move across a row of 100 squares. The rule was to pick the square that lit up most intensely. That square was always near the middle, but squares farther to the right paid more money, so people figured out fairly quickly that cheating had a payoff. After a first choice, participants saw the choice of another player who had either (a) committed a minor violation (about one-third of the way toward the highest-paying square), (b) committed a major violation (picked the rightmost square), or (c) followed the rule. Then the player chose again. Everyone did this a bunch of times.

People were already bending the rule before seeing anyone else, with first choices averaging 0.34 on a scale from 0 (full compliance) to 1 (full rule-breaking). Seeing a minor violation raised rule breaking in the subsequent round by 0.07, on average, and seeing a major violation raised rule-breaking by 0.15. But Seeing a rule-follower had no significant impact on the subsequent round at all. 

This one-way winch on individuals, pushing them toward rule-breaking, seems like a pretty clear indictment of human behaviour whenever a group faces a moral dilemma. But these results might just reflect the artificiality of the set-up. Perhaps a different version of this game, with clearer consequences for rule-breaking, might result in a different dynamic. I sure hope so!

I was unable to attend the North American Symposium on Bat Research this year, in Fort Collins CO, but apparently there was a "pop-up tattoo table" there (is that really a thing???), and people were getting bat-themed tattoos.

Imagine my surprise to see that one person got my PhD data as a tattoo!! This sequence of running vampires comes straight from a pair of papers I published - one in Nature and one in the Journal of Experimental Biology - where I showed image sequences of common vampire bats running on a treadmill.

Vampire bats are the only bats that run. I think that's something most bat biologists think is cool, but to my knowledge, Professor Amy Russell, of Grand Valley State University in Allendale MI, is the first person to get a tattoo of it!

Isn't that cool??? I'm tickled.

Ants have been using venom as a weapon for well over 100 million years, but one tiny species in Japan has turned its venom gland into something new: a glue gun. Workers of Lordomyrma azumai push a sticky secretion out of the tip of their stinger, and it hardens almost instantly into a continuous thread. The ant doesn't inject the glue (so it’s not technically a venom – venoms must be injected, by definition). Instead, it wipes the thread onto an enemy. The enemy tries to clean itself, but ends up getting covered in soil and other debris, instead. Scientists observed nine glue-gunned victims to see what effects the glue has. Within 24 hours, eight (89%) were dead, dismembered by nestmates (it’s an ant-eat-ant world).

As far as the authors know, no other stinging insect has modified its venom to make a solid thread. The glue kind of reminds me of spider thread, but it's much less sophisticated or versatile. Maybe this is a hint about how spider thread first evolved!

Note: This is still just a pre-print, and hasn't been through peer review yet.

Last Week's Trivial Answer

Last week's question was "What U.S. Capital has the highest elevation?" The correct answer was "Santa Fe, New Mexico."

Thanks for reading! -Dan