Science news in brief: from venomous moles to snakes with legs

And other news from around the world

Bats have been shown to pollinate durians in Indonesia (Wildlife Conservation Society)

They’re smelly and spiky and need bats to pollinate them

Known as the world’s smelliest fruit, durians are essential to the farming economy of Indonesia. Although repulsive to many Western noses – some compare the smell to rotting rubbish – durians command the highest unit price of any fruit in Indonesia, with an export value of more than $250m (£190m) in 2013.

Hoping to help improve the yield of small-scale farmers, three researchers decided to figure out what kind of creatures pollinate the durians in Sulawesi, a large island at the centre of Indonesia.

In a three-step process, the team first tested the plants to figure out what time of day pollination usually occurred. Evenings, they discovered, were prime time, as each flower opens for a single night and produces pollen only that one night.

Then the researchers put bags on some of the flowers. Some bags had holes big enough for bugs but not larger creatures, and some had no holes at all. The bagged plants did not yield fruit, suggesting that something bigger than a bug was responsible for pollination.

Finally, the researchers set up nighttime cameras to figure out which species of birds or bats was most responsible for the pollination. They reported in the journal Biotropica that they caught three species of bats in the act, including a cave nectar bat and two types of flying foxes.

The last two were a surprise, says Holly Ober, an associate professor and extension specialist at the University of Florida in Quincy. Flying foxes are known to eat fruit smaller than durians and are often killed by farmers trying to protect their mango crop.

Some people also kill bats to sell as bushmeat. “Now that we know that these bats are important to helping farmers produce more durians, we can start getting the message out that folks should not be causing harm to these bats,” Ober says.

The fruit’s odour is akin to rotting rubbish (Getty/iStock)

Joseph Walston, senior vice president for global programmes at the Wildlife Conservation Society, says bats were often overlooked as key contributors to an ecosystem.

Bats come out at night and inspire horror stories, but “they are so utterly fundamental to our ecosystems, to our economies and to our health”, he says. And yet, they are rarely offered support and protection, he adds.

“This study really is trying to provide empirical evidence for why we as a community should do more for bats,” Walston says.

A fossil belonging to the extinct snake group Najash, which still retained their hind legs (Fernando Garberoglio)

When snakes had use for a pair of legs

Snakes, with their sleek bodies and kaleidoscopic diversity, have long entranced humans. But we know very little about the evolutionary past of these legless lizards because of a scarcity of fossils left by snake ancestors that shared the earth with dinosaurs.

That’s why recently excavated snake fossils from Argentina, described in a study published last month in Science Advances, are such a big deal. The intricate fossils, mostly skulls, are nearly 100 million years old and belong to the extinct snake group Najash, which still retained hind legs. The fossils suggest that snakes lost their front legs much earlier than had previously been believed but also held onto their hind legs for millions of years. The find will also help to resolve mysteries over when snakes began their transition to their modern form.

This find is the most complete Mesozoic snake skull known (Fernando Garberoglio)

Fernando Garberoglio, who led the research, discovered the most spectacular of these new skull specimens, called MPCA 500, in 2013 when he was an undergraduate student.

“That skull is now the most complete Mesozoic snake skull known and preserves key data on ancient snake anatomy,” says Garberoglio, who is pursuing a PhD at the Fundacion Azara at Universidad Maimonides in Buenos Aires.

The exceptional preservation of the fossils enabled Garberoglio and his colleagues to study long-standing mysteries about snake development, such as the sequence of events that led to their limbless bodies.

Scientists have not found fossils of the snake family’s four-legged ancestors, though they are certain these tetrapod forebears existed. The new study suggests that those mysterious proto-snakes probably lost their forelimbs early in snake evolution, at least 170 million years ago. But the back legs stuck around for tens of millions of years.

The Najash group were around for aeons before most snakes transitioned into fully limbless slitherers (Raul Orencio Gomez)

That means that hind-legged snakes, such as the Najash group, did not represent a short-lived evolutionary phase. Instead, snakes retaining two of their legs were a successful body plan that sufficed for aeons until most snakes transitioned into fully limbless slitherers during the latter half of the Cretaceous period.

“‘Snakeness’ is really old, and that’s probably why we don’t have any living representatives of four-legged snakes like we do all of the other lizards,” says Michael Caldwell, a vertebrate palaeontologist at the University of Alberta and a co-author of the study.

“Snakes probably were one of the first lizard groups to start experimenting with limblessness, but what’s really intriguing is that they were also very clearly showing the characteristics of their skulls, which are their specialisation.”

Titan is Saturn’s biggest moon (JPL-Caltech/Nasa)

Go ahead, take a spin on titan

How weird can nature get?

Try Titan, Saturn’s largest moon, almost 900 million cold miles from the sun and even further, perhaps, from the feeble limits of human imagination.

This is a world where it rains gasoline. Rivers have carved canyons through mountains of frozen hydrocarbons, and layers of ice float on subsurface oceans of ammonia. A chemical sludge that optimistic astronomers call “prebiotic” creeps along under an oppressive brown sky. Besides Earth, Titan is the only world in the universe that is known to harbour liquid on its surface – and everything that could imply.

For almost four centuries, Titan was just a mysterious brown dot in the sky. Time, technology and human ingenuity have since revealed that dot, Titan, to be a natural wonderland. Last month in Nature Astronomy, planetary scientists and geologists from Nasa’s Jet Propulsion Laboratory and Arizona State University, led by Rosaly Lopes of JPL, published what they called the first geologic map of the distant, frigid world.

The map is based on radar measurements from the Cassini orbiter, which landed a probe on Titan. The map shows the locations of a wide variety of geological terrains, from lakes, dunes, craters and plains to more exotic features, including hummocks (rolling hills) and labyrinthine channels cut by rain or rivers.

Water is the key to life as we know it, which is why Nasa’s exoplanet searches are oriented towards finding planets warm enough to harbour oceans or lakes. But some investigators in the hopeful field of astrobiology speculate that there might exist a life as we don’t know it thriving on some other liquid.

And so Titan, with its rains, rivers, lakes and subsurface ocean of ammonia and water, has risen to the top of the list of homes for possible weird life out there. Awash in organic materials, Titan is thought by many scientists to resemble in some ways the early Earth before evolution caught on. But stuck in a deep freeze, everything on Titan moves much more slowly.

Nasa and planetary scientists plan to launch an aircraft called Dragonfly to utilise the moon’s relatively thick atmosphere to hop around and inspect different regions, with the aim of figuring out how this world, with its strange weather and chemistry, works.

Dragonfly would land on Titan in 2034, on the Shangri-La dune fields near the moon’s equator. Over the next three years, Dragonfly – a drone-like helicopter with eight rotors – will skip from site to site, poking, measuring and taking it all in.

The Hispaniolan solenodon lives in the forests of the Dominican Republic and Haiti (Lucy Emery)

How a curious mammal evolved its venom

The Hispaniolan solenodon is a wondrously strange creature.

About the size of a guinea pig, it has a long, hairless snout, sharp little teeth and, to top it all off, venom-laced saliva. Highly endangered, it lives quietly in the forests of the Dominican Republic and Haiti, and scientists have been hard-pressed to understand much about its habits and evolution. But in a paper published last month in the Proceedings of the National Academy of Sciences, a diverse group of researchers outline the intriguing conclusions they reached about how the solenodon got its dangerous spit after they sequenced its genome and analysed its venom.

It was not easy finding solenodons to study, says Nicholas Casewell, a venom expert at the Liverpool School of Tropical Medicine and a co-author of the new paper. The team managed to track down two of the animals in the wild with venom they could sample. At the National Zoological Park in the Dominican Republic, they took blood for genome sequencing from another solenodon – one of a handful of captive specimens in the world. They compared the genome to those of related animals, like hedgehogs, moles and shrews, and identified substances present in the venom, including a set of enzymes called kallikreins.

The venom-delivery tooth of the Hispaniolan solenodon (Nicholas Casewell)

Kallikreins mince up other proteins, including some involved in maintaining blood pressure. The researchers injected mice with solenodon venom and saw that indeed, while their pulse and breathing did not change, their blood pressure dropped precipitously as soon as the venom went in. This could render prey foggy-headed and easier for the solenodon to finish off, the researchers suggest.

Another venomous mammal among the solenodon’s relatives, the northern short-tailed shrew, also has kallikreins in its venom.

“To us, it was a real surprise to find very similar proteins in the venom of the solenodon and shrews,” Casewell says.

They asked whether venom might have existed in the common ancestor of moles, hedgehogs, shrews and solenodons. The researchers concluded that it is more likely that shrews and solenodons came up with the adaptation after they branched off from these other small mammals.

But the fact that there is an overlap in these enzymes in two different animals implies that mammals have a very limited palette of options to work with when it comes to ginning up a venom.

A projectile is obliterated upon impact, while the target breaks up in stages over the following months (Olivier Hainaut)

This is what it looks like when an asteroid gets destroyed

The asteroid belt, hanging out between Mars and Jupiter, is not like the cluttered debris field in The Empire Strikes Back. It may contain millions of rocky and metal objects, but the distances separating them are vast, and collisions are rare.

That is what makes P/2016 G1 such an exciting object. Spotted zipping through the asteroid belt in early 2016, this object had a strange orbit and a tail of dust that resembled a comet.

What they had stumbled across was not a comet, but the immediate aftermath of an asteroid’s assassination.

On or around 6 March 2016, an asteroid at least 1,300 feet in diameter was minding its own business when another space rock, weighing around 2.2 pounds and perhaps 1 foot long or so, slammed into the larger asteroid at roughly 11,000 mph. That’s about five times as fast as a bullet fired from a rifle. The projectile was obliterated upon impact; the target then broke up in stages over the coming months.

Without this collision, these two small objects would have remained forever anonymous. Instead, scientists gained a serendipitous insight into the destructibility of asteroids, which could help defend Earth against future asteroid hazards. After all, “the best way to see how hard something is, is to break it”, says Olivier Hainaut, an astronomer at the European Southern Observatory and lead author of the study published earlier this year in Astronomy and Astrophysics.

Astronomers first discovered P/2016 G1 in April 2016. Backtracking through archived images, astronomers realised that it had first been visible the previous month as a centralised collection of rocky clumps: the fractured, rubbly remnants of the asteroid, surrounded by a fine dust cloud, most likely the immediate debris jettisoned by the impact.

After the initial debris cloud was created, the cratering process lost energy and subsequent streams of debris were more slowly excavated from the asteroid’s new scar.

There is no clear date when the asteroid disappeared. Documenting the vanishing of P/2016 G1 was like tracking a drop of milk in your coffee, Hainaut says: Parts spread out and faded away individually.

Knowing what types of impacts cause deflections and disruption is key to Earth’s protection from errant asteroids. That makes the demise of P/2016 G1 a vital source of information, says Megan Bruck Syal, a planetary defence researcher at the Lawrence Livermore National Laboratory who was not involved with the study.

© New York Times