Isegoria

Imagine emerging into the sun after 17 long years spent lying underground, Ed Yong suggests, only for your butt to fall off:

That ignominious fate regularly befalls America’s cicadas. These bugs spend their youth underground, feeding on roots. After 13 or 17 years of this, they synchronously erupt from the soil in plagues of biblical proportions for a few weeks of song and sex. But on their way out, some of them encounter the spores of a fungus called Massospora.

A week after these encounters, the hard panels of the cicadas’ abdomens slough off, revealing a strange white “plug.” That’s the fungus, which has grown throughout the insect, consumed its organs, and converted the rear third of its body into a mass of spores. The de-derriered insects go about their business as if nothing unusual has happened. And as they fly around, the spores rain down from their exposed backsides, landing on other cicadas and saturating the soil. “We call them flying saltshakers of death,” says Matt Kasson, who studies fungi at West Virginia University.

Massospora and its butt-eating powers were first discovered in the 19th century, but Kasson and his colleagues have only just shown that it has another secret: It doses its victims with mind-altering drugs. Perhaps that’s why “the cicadas walk around as if nothing’s wrong even though a third of their body has fallen off,” Kasson says.

[...]

Greg Boyce, a member of Kasson’s team, looked at all the chemicals found in the white fungal plugs of the various cicadas. And to his shock, he found that the banger-wings were loaded with psilocybin—the potent hallucinogen found in magic mushrooms. “At first, I thought: There’s absolutely no way,” he says. “It seemed impossible.” After all, no one has ever detected psilocybin in anything other than mushrooms, and those fungi have been evolving separately from Massospora for around 900 million years.

The surprises didn’t stop there. “I remember looking over at Greg one night and he had a strange look on his face,” Kasson recalls. “He said, ‘Have you ever heard of cathinone?’” Kasson hadn’t, but a quick search revealed that it’s an amphetamine. It had never been found in a fungus before. Indeed, it was known only from the khat plant that has long been chewed by people from the Middle East and the Horn of Africa. But apparently, cathinone is also produced by Massaspora as it infects periodical cicadas.

[...]

Infected cicadas behave strangely. Despite their horrific injuries, males become hyperactive and hypersexual. They frenetically try to mate with anything they can find, including with other males. They’ll even mimic the wing-flicking signals of females to lure males toward them. None of this does them any good—their genitals have either been devoured by the fungus or have fallen off with the rest of their butts. Instead, this behavior only benefits the fungus, allowing its spores to find new hosts.

Kasson suspects that cathinone and psilocybin are responsible for at least some of these behaviors. “If I had a limb amputated, I probably wouldn’t have a lot of pep in my step,” he said. “But these cicadas do. Something is giving them a bit more energy. The amphetamine could explain that.”

Psilocybin’s role is harder to explain. The drug might make humans hallucinate, but no one knows if cicadas would similarly trip. There is, however, a theory that magic mushrooms evolved psilocybin to reduce the appetites of insects that might compete with them for decaying wood. Perhaps by suppressing the appetites of cicadas, Massospora nudges them away from foraging and toward incessant mating.

There are many parasitic fungi that manipulate the behavior of insect hosts, including the famous Ophiocordyceps fungi, which can turn ants into zombies.

This is how a zombie outbreak could (semi-plausibly) happen.

The saiga is “an endearing antelope” that roams Central Asia. Its “bulbous nose gives it the comedic air of a Dr. Seuss character,” Ed Yong says:

It typically wanders over large tracts of Central Asian grassland, but every spring, tens of thousands of them gather in the same place to give birth. These calving aggregations should be joyous events, but the gathering in May 2015 became something far more sinister when 200,000 saiga just dropped dead. They did so without warning, over a matter of days, in gathering sites spread across 65,000 square miles — an area the size of Florida. Whatever killed them was thorough and merciless: Across a vast area, every last saiga perished.

At first, the team suspected that a new infectious disease had spread through the population, but the pattern of deaths just didn’t fit. The saiga were dying too synchronously and too quickly. Also, all of them had died. “In biology, there’s certain rules, you know?” says Kock. “We accept that sometimes microbes can cause us harm, but not like this. Even very severe viral diseases or anthrax don’t do this. A good proportion of the animals would be fine.”

News of the die-off sparked outlandish explanations about Russian rocket fuel, radiation, and even aliens. But while conspiracy theories raged, a huge international team of scientists, led by Kock, got to work. Vets autopsied as many saigas as they could. Ecologists sampled the soil. Botanists checked the local plants. They couldn’t find any signs of toxins that might have killed the saiga. Instead, the actual culprit turned out to be a bacterium, one that’s usually harmless.

Pasteurella multocida normally lives in the saiga’s respiratory tract, but Kock’s team found that the microbe had found its way into the animals’ blood, and invaded their livers, kidneys, and spleens. Wherever it went, it produced toxins that destroyed the local cells, causing massive internal bleeding. Blood pooled around their organs, beneath their skin, and around their lungs. The saigas drowned in their own bodily fluids.

But that answer just led to more questions. Pasteurella is common and typically harmless part of the saiga’s microbiome. In livestock, it can cause disease when animals are stressed, as sometimes happens when they’re shipped over long distances in bad conditions. But it has never been linked to a mass die-off of the type that afflicted the saigas. What could have possibly turned this docile Jekyll into such a murderous Hyde?

The team considered a list of possible explanations that runs to 13 pages. They wondered if some environmental chemical or dietary change had set the microbe off. They checked if biting insects had transmitted a new infection that interacted with Pasteurella. They considered that Pasteurella might have gone rogue because of an accompanying viral infection, in the same way that Streptococcus bacteria can bloom during a cold, leading to strep throat. “We tested for everything and we couldn’t find anything,” says Eleanor Milner-Gulland from the University of Oxford.

Only one factor fit the bill: climate. The places where the saigas died in May 2015 were extremely warm and humid. In fact, humidity levels were the highest ever seen the region since records began in 1948. The same pattern held for two earlier, and much smaller, die-offs from 1981 and 1988. When the temperature gets really hot, and the air gets really wet, saiga die. Climate is the trigger, Pasteurella is the bullet.

It’s still unclear how heat and humidity turn Pasteurella into a killer, and the team is planning to sequence the bacterium’s genome to find out more.

Blackbirds, Ed Yong explains, aren’t actually all that black:

Their feathers absorb most of the visible light that hits them, but still reflect between 3 and 5 percent of it. For really black plumage, you need to travel to Papua New Guinea and track down the birds of paradise.

Although these birds are best known for their gaudy, kaleidoscopic colors, some species also have profoundly black feathers. The feathers ruthlessly swallow light and, with it, all hints of edge or contour. They make body parts seem less like parts of an actual animal and more like gaping voids in reality. They’re blacker than black. None more black.

By analyzing museum specimens, Dakota McCoy, from Harvard University, has discovered exactly how the birds achieving such deep blacks. It’s all in their feathers’ microscopic structure.

A typical bird feather has a central shaft called a rachis. Thin branches, or barbs, sprout from the rachis, and even thinner branches—barbules—sprout from the barbs. The whole arrangement is flat, with the rachis, barbs, and barbules all lying on the same plane. The super-black feathers of birds of paradise, meanwhile, look very different. Their barbules, instead of lying flat, curve upward. And instead of being smooth cylinders, they are studded in minuscule spikes. “It’s hard to describe,” says McCoy. “It’s like a little bottle brush or a piece of coral.”

These unique structures excel at capturing light. When light hits a normal feather, it finds a series of horizontal surfaces, and can easily bounce off. But when light hits a super-black feather, it finds a tangled mess of mostly vertical surfaces. Instead of being reflected away, it bounces repeatedly between the barbules and their spikes. With each bounce, a little more of it gets absorbed. Light loses itself within the feathers.

McCoy and her colleagues, including Teresa Feo from the National Museum of Natural History, showed that this light-trapping nanotechnology can absorb up to 99.95 percent of incoming light. That’s between 10 and 100 times better than the feathers of most other black birds, like crows or blackbirds. It’s also only just short of the blackest materials that humans have designed. Vantablack, an eerily black substance produced by the British company Surrey Nanosystems, can absorb 99.965 percent of incoming light. It consists of a forest of vertical carbon nanotubes that are “grown” at more than 750 degrees Fahrenheit. The birds of paradise mass-produce similar forests, using only biological materials, at body temperature.

Swamp Park, in southeastern North Carolina, is at the northern extreme for American alligators, which means it can get a little cold for the cold-blooded reptiles:

At first, [George Howard, the park’s general manager] thought the water had too many cypress knees – woody projections from tree roots that are a common sight in swamps.

Then he saw teeth.

When it’s cold but not icy, the alligators disappear, sinking to the bottom of the swamp for most of the day or burrowing into the mud, Howard said. “You don’t see them, but they’re under there.”

[...]

Right before the surface freezes, they stick their snouts out of the water so they can continue breathing.

Iguanas, by the way, react somewhat differently to the cold:

And in Florida, where temperatures took a rare dip into the 40s last week, iguanas also slowed their bodily functions. But because many are tree dwellers, some just fell to the ground.

It was a repeat of a cold snap in 2010, when the iguana situation caught people similarly unawares.

“Neighbourhoods resounded with the thud of iguanas dropping from trees onto patios and pool decks, reptilian Popsicles that suggested the species may not be able to retain its claw-hold on South Florida,” the Sun-Sentinel’s David Fleshler wrote.

But the story had a happy ending, Fleshler reported. The iguanas “have rebounded, repopulating South Florida neighbourhoods and resuming their consumption of expensive landscaping.”

By the way, the term brumation was coined in 1965, so reptiles could have their own term for hibernation.

Raptors — the black kite, whistling kite, and brown falcon — are intentionally spreading grass fires in northern Australia:

Raptors on at least four continents have been observed for decades on the edge of big flames, waiting out scurrying rodents and reptiles or picking through their barbecued remains.

What’s new, at least in the academic literature, is the idea that birds might be intentionally spreading fires themselves. If true, the finding suggests that birds, like humans, have learned to use fire as a tool and as a weapon.

Gosford, a lawyer turned ethno-ornithologist (he studies the relationship between aboriginal peoples and birds), has been chasing the arson hawk story for years. “My interest was first piqued by a report in a book published in 1964 by an Aboriginal man called Phillip Roberts in the Roper River area in the Northern Territory, that gave an account of a thing that he’d seen in the bush, a bird picking up a stick from a fire front and carrying it and dropping it on to unburnt grass,” he told ABC.

“MJ,” a Kimberley, (Western Australia) cattle station caretaker manager … saw kites working together to move a late dry season fire across a river by picking up, transporting, and dropping small, burning sticks in grass, which immediately ignited in several places,” they write. “The experience resulted in an uncontrollable blaze that destroyed part of the station’s infrastructure.”

Bob White, a firefighter in the Northern Territory saw a small group of raptors, likely black kites, “pick up numerous smouldering sticks and transport them ahead of a fire front, successfully helping the blaze spread up a small valley.”

Nathan Ferguson claims to have observed fire spreading about a dozen times in the Northern Territory since 2001. The long-time firefighter is adamant that the birds he’s observed — picking up twigs and starting new fires — were doing so on purpose.

That jibes with the other research Gosford and Bonta dug up. “Most accounts and traditions unequivocally indicate intentionality on the part of three raptor species,” they wrote.

Dogs are not super-cooperative wolves:

She and her colleagues challenged their canines to a simple task, which other scientists have used on all kinds of brainy animals — chimps, monkeys, parrots, ravens, and even elephants. There’s a food-bearing tray that lies on the other side of their cage, tempting and inaccessible. A string is threaded through rings on the tray, and both of its ends lie within reach of the animals. If an individual grabs an end and pulls, it would just yank the string out and end up with a mouthful of fibers — not food. But if two animals pull on the ends together, the tray slides close, and they get to eat.

All in all, the dogs did terribly. Just one out of eight pairs managed to pull the tray across, and only once out of dozens of trials. By contrast, five out of seven wolf pairs succeeded, on anywhere between 3 and 56 percent of their attempts. Even after the team trained the animals, the dogs still failed, and the wolves still outshone them. “We imagined that we would find some differences but we didn’t expect them to be quite so strong,” Marshall-Pescini says.

It’s not that the dogs were uninterested: They explored the strings as frequently as the wolves did. But the wolves would explore the apparatus together — biting, pawing, scratching, and eventually pulling on it. The dogs did not. They tolerated each other’s presence, but they were much less likely to engage with the task at the same time, which is why they almost never succeeded.

“The dogs are really trying to avoid conflict over what they see as a resource,” says Marshall-Pescini. “This is what we found in food-sharing studies, where the dominant animal would take the food and the subordinate wouldn’t even try to approach. With wolves, there’s a lot of arguing and it sounds aggressive, but they end up sharing. They have really different strategies in situations of potential conflict. [With the dogs], you see that if you avoid the other individual, you avoid conflict, but you can’t cooperate either.”

“Amazingly, no one had ever studied whether carnivores could solve this type of cooperative task, and it’s fun to see that the wolves coordinated,” says Brian Hare from Duke University, who studies dog behavior and the influence of domestication. He has argued that during the domestication process, dogs began using their traditional inherited mental skills with a new social partner: humans.

Simultaneously, dogs perhaps became less attentive to each other, adds Marshall-Pescini. After all, wolves need to work together to kill large prey, and sharing food helps to keep their social bonds intact. But when they started scavenging on human refuse, they could feed themselves on smaller portions by working alone. If they encountered another forager, “maybe the best strategy was to continue searching rather than to get into conflict with another dog,” she says.

But dogs can be trained. When owners raise dogs in the same household, and train them not to fight over resources, the animals start to tolerate each other, and unlock their ancient wolflike skills. This might be why, in 2014, Ljerka Ostojic, from the University of Cambridge, found that pet dogs, which had been trained in search and rescue, had no trouble with the string-pulling task that flummoxed Marshall-Pescini’s dogs.

“It speaks to the fact that living among other dogs, without interaction with humans, is arguably less natural for dogs — as if domestication both refined attention, coordination, and even pro-sociality between species, and weakened social skills within the species,” says Alexandra Horowitz, who studies dog cognition at Barnard College. “A pack of dogs living together, without human intervention, is impaired compared to dogs living with humans.”

Being bitten by an Australian tiger snake is a wholly unpleasant experience:

Within minutes, you start to feel pain in your neck and lower extremities — symptoms that are soon followed by tingling sensations, numbness, and profuse sweating. Breathing starts to become difficult, paralysis sets in, and if left untreated, you’ll probably die. Remarkably, the venom responsible for these horrifying symptoms has remained the same for 10 million years — the result of a fortuitous mutation that makes it practically impossible for evolution to find a counter-solution.

[...]

The secret to tiger snake venom has to do with its biological target — a clotting protein called prothrombin. This critically important protein is responsible for healthy blood clotting, and it exists across a diverse array of animal species (humans included). Any changes to this protein and the way it works can be catastrophic to an animal, leading to life-threatening conditions such as hemophilia. It’s this vulnerable target that makes the tiger venom so potent, but at the same time, animals are under intense evolutionary pressure to maintain prothrombin in its default, functional state. As Fry explained in a release, if the animals had any variation in their blood clotting proteins, “they would die because they would not be able to stop bleeding.”