Science news in brief: From venomous slow lorises to glowing Venus flytraps

Slow lorises are adorable but they bite with flesh-rotting venom

With their bright saucer eyes, button noses and plump, fuzzy bodies, slow lorises — a group of small, nocturnal Asian primates — resemble adorable, living stuffed animals. But their innocuous looks belie a startling aggression: they pack vicious bites loaded with flesh-rotting venom. Even more surprising, new research reveals that the most frequent recipients of their toxic bites are other slow lorises.

“This very rare, weird behaviour is happening in one of our closest primate relatives,” says Anna Nekaris, a primate conservationist at Oxford Brookes University and lead author of the findings, published in Current Biology.

Researchers are just beginning to untangle the many mysteries of slow loris venom. One key component resembles the protein found in cat dander that triggers allergies in humans. But other unidentified compounds seem to lend additional toxicity and cause extreme pain. Strangely, to produce the venom, the melon-sized primates raise their arms above their head and quickly lick venomous oil-secreting glands located on their upper arms. The venom then pools in their grooved canines, which are sharp enough to slice into bone.

“The result of their bite is really, really horrendous,” Nekaris says. “It causes necrosis, so animals may lose an eye, a scalp or half their face.”

To get to the bottom of how slow lorises use their venom in nature, Nekaris used radio collars to track 82 Javan slow lorises, a critically endangered species in Indonesia. Like other types of slow lorises, Javan slow lorises form long-term mating pairs that occupy small territories containing one or several gum-producing trees.

Over an eight-year span, the researchers spent more than 7,000 hours monitoring their study subjects in a 2sqm patch of forest. They recaptured the animals every few months for health checks.

Shockingly, across all captures, 20 per cent of slow lorises had fresh bite wounds — often severe, flesh-rotting injuries that entailed a lost ear, toe or more. Males suffered more frequent bites than females, as did young animals dispersing from their parents’ territories. While necrotic wounds were a regular occurrence, predation was not; since 2012, the researchers have lost just one Javan slow loris to a predator, which was a feral dog.

Nekaris and her colleagues conclude that slow lorises are remarkably territorial and that they frequently use their venom to settle disputes.

— Rachel Nuwer

Why scientists made Venus flytraps that glow

Provoking a Venus flytrap takes a certain amount of finesse. If you brush just one of the trigger hairs inside of its leaves, the plant likely won’t react. But if you trigger it again quickly enough, it will spring into action, swinging its famous mouth shut.

 Despite centuries of interest in the species, no one was quite certain how the plants remember the first trigger in order to act on a second.

In a paper published in Nature Plants, researchers report they have found the cause: calcium ions. By inducing the flytraps to glow when calcium entered their cells, a team of scientists have been able to show how the ions build up as the hairs are triggered, eventually causing the snap.

Calcium is used for conveying information between cells in many different life forms, says Mitsuyasu Hasebe, leader of the lab at the National Institute for Basic Biology in Okazaki, Japan, where the research was done.

To visualise the flytrap’s memory mechanism, Hasebe and his colleagues spliced a special type of gene into the plant. This gene, widely used in biology, produces a protein that turns fluorescent green when it binds to a target — in this case, a calcium ion.

Hiraku Suda — the paper’s lead author and a doctoral student in Hasebe’s lab at the time of the research — was in charge of integrating the gene, which required infecting the plant’s leaves with a modified bacterium and then using those leaves to grow new shoots.

It took him two-and-a-half years to figure it out. The key, it turned out, was raising the plants in the dark, which may have made them easier to infect with the bacteria.

Next, the researchers started poking the plant. After a single tap to a sensory hair, a green flush appeared at the hair’s base and quickly spread across the leaves, indicating a surge of calcium ions.

A second tap within about 30 seconds spurred an additional surge, pushing the total calcium amount over a threshold that caused the trap to close. But if the researchers waited too long between taps, the concentration decreased again, and the trap didn’t budge.

Suda, now a postdoctoral fellow at Saitama University in Japan, plans to use his new method to study the capturing of prey, digestion and other activities of the flytrap.

— Cara Giaimo

Melting ice reveals mummified penguins in Antarctica

In January 2016, Steven Emslie was finishing a season of studying penguin colonies living near Zucchelli Station, an Italian base in Antarctica. With the austral summer quickly coming to a close and all planned work completed, Emslie, an ornithologist at the University of North Carolina, Wilmington, did what any good scientist would do with a few extra days in the Antarctic: he went exploring.

He had heard rumours of penguin guano on a rocky cape along the Scott Coast but knew of no active colonies there. Emslie immediately knew he had stumbled upon something intriguing when he arrived. “There were pebbles everywhere,” he recalls.

While pebbles are an everyday find on other continents, it is rare to spot them in abundance on dry land in Antarctica. A key exception is found in Adelie penguin colonies, as the birds collect the small stones from the beaches to build their nests.

Then Emslie saw the guano. Then he found the penguin corpses. With feathers still intact and flesh having barely decayed, Emslie was stunned. He collected some remains and took them back for carbon-dating analysis to work out when the birds had died.

With dates of death that ranged from 800 to 5,000 years ago, Emslie immediately realised that the guano, feathers, bones and pebbles had all been locked in place under layers of ice for centuries and that the “freshly dead” penguins were in fact recently defrosted mummies that had been swallowed by advancing snowfields long ago.

Emslie speculates in the journal Geology, where he reported his findings in mid-September, that cooling temperatures drove a type of sea ice to form along the coast that persisted well into summer months. Known as “fast ice” because it “fastens” to the coastline, this sea ice makes it very difficult for penguins to gain access to beaches and prevents them from colonizing places where it occurs.

He says he thought the ice forced the colony to be abandoned but also suggested that warming temperatures might change things in the years ahead.

With Antarctic ice melting and sea levels rising, established penguin colonies are being forced to disperse to new places. Emslie suggests that the penguins could then return to sites like this one.

“They need pebbles for their nests, so they are going to find all the pebbles that are already on the land at this site very attractive,” he says.

— Matt Kaplan

People with this mutation can’t smell stinky fish

A small contingent of the world’s population carries a mutation that makes them immune to the odious funk that wafts off fish, according to a study of some 11,000 people published in the journal Current Biology. 

The trait is rare, but potent: when faced with a synthetic odour that would put many people off their lunch, some test subjects smelled only the pleasant aroma of caramel, potato or rose.

 Nearly 98 per cent of Icelanders, the research says, are probably as put off by the scent as you’d expect.

“I can assure you I do not have this mutation,” says Dr Kari Stefansson, a neurologist and the study’s senior author. “I tend to get nauseated when I get close to fish that is not completely fresh.”

Study participants were asked to smell six Sniffin’ Sticks — pens imbued with synthetic odours resembling the recognisable scents of cinnamon, peppermint, banana, liquorice, lemon and fish. They were asked to identify the smell, then rate its intensity and pleasantness.

The older the study subjects were, the more they struggled to accurately pinpoint the scents. 

The reek of fish, however, was mostly recognisable and received the lowest pleasantness ratings among the six sticks. But a small group of people consistently tolerated or even welcomed the piscine perfume: those born with a genetic mutation that incapacitated a gene called TAAR5.

TAAR5 helps make a protein that recognises a chemical called trimethylamine, or TMA, that is found in rotten and fermented fish and certain animal bodily fluids.

Most people carry an intact version of TAAR5 and easily recognise the fishy fragrance as mildly repulsive — an ability that might have evolved to help our ancestors avoid spoiled food. But a small number of the Icelanders in the study carried at least one “broken” copy of the gene that appeared to render them insensitive to the scent. When asked to describe it, some even mistook it for a sugary dessert, ketchup or something floral.

A blunted sense for bad-smelling fish might sound maladaptive. But TMA doesn’t always spell trouble, especially in Iceland, where fish features prominently on many menus.

That might be why the TAAR5 mutation appears in more than 2 per cent of Icelanders but a much smaller proportion of people in Sweden, Southern Europe and Africa, the researchers found.

Paule Joseph, an expert in sensory science at the National Institutes of Health, notes that these genetic changes could affect, or be affected by, dietary patterns.

— Katherine J Wu

Why male baboons benefit from female friends

New research has shown that platonic relationships between baboons might be just as important as the relationships that make more baby monkeys. Male baboons live longer if they have more female friends.

The findings, published in Philosophical Transactions of the Royal Society B, came from one of the world’s longest-running studies of wild primates. Researchers have been continuously observing savanna baboons in Kenya’s Amboseli basin since 1971. They’ve amassed a data set that includes the births and deaths of hundreds of animals, as well as the baboons’ daily activities. One activity, grooming, is the basis for baboons’ social relationships.

“Grooming’s really interesting behaviour”, in part because it isn’t always reciprocated, says Fernando Campos, a biological anthropologist at the University of Texas at San Antonio and one of the lead authors.

Although males and females may groom each other, there isn’t much male to male grooming or bonding in the Amboseli population. Pairs of female baboons, on the other hand, form “lifelong bonds”, Campos says, and earlier research has shown that female baboons with strong relationships live longer than socially isolated females.

But what about male baboons? That question has been harder to study because every few years or so, males join a new social group. If a male baboon disappears from the Amboseli study population, scientists can’t tell whether he has died or joined another group farther away.

In the new paper, biologists and statisticians collaborated on a model that addressed that problem. Their data set included 542 adult baboons, both male and female, observed over more than three decades. Based on the occasional deaths or moves that humans actually witnessed, and the age of the male baboons when those events happened, the scientists could calculate the likelihood that any other vanished male had either died or migrated.

Just as with female baboons, they saw that males with more social bonds — those platonic grooming relationships with females — lived longer.

It’s not clear why, though.

Baboons of either sex might get health benefits simply from having their parasites picked off. Friendships might also help the animals avoid conflicts. Studies in other primates have found that social relationships reduce physiological signs of stress.

It’s also possible, Campos says, that causation goes the other way. Maybe healthier animals have more energy to invest in relationships.

— Elizabeth Preston

© The New York Times