Research Highlights

Our pick of the latest scientific literature

  • Volume 546
  • Issue 7659

Genomics

How cats came to dominate the world

Domestic felines followed trade routes to spread into Europe.

Feline remains at ancient burial sites suggest that domestic cats existed in early societies in the Near East and Egypt. But scientists know little about how the animals advanced across the world.

Eva-Maria Geigl at the Institute Jacques Monod in Paris and her colleagues analysed mitochondrial DNA from 209 cats that lived between about 8000 BC and the twentieth century.

They found two distinct populations that contribute to modern domestic cats, one of which appeared in the Middle East and spread to Europe as early as 4400 BC. A separate lineage, initially common only to ancient Egyptian cats, spread to Europe and the Middle East from the fifth century AD onwards.

This move mirrors ancient trade routes, suggesting that a role as ship’s rat catcher might have helped cats to spread to Europe and beyond.

Technology

Ground-to-air quantum link achieved?

Researchers have transmitted photons to a speeding aircraft, demonstrating technology for space-based quantum communication.

Quantum encryption is secure because the laws of quantum physics guarantee that any eavesdropping would be detectable. But photons, which are used encode a shared quantum key, can travel only relatively short distances through fibres or air before being absorbed, making transmission through space more appealing for long-distance communication.

Thomas Jennewein at the University of Waterloo, Canada, and his collaborators sent photons to a receiver mounted on an aircraft passing overhead at the same apparent rate as a satellite and over distances of up to 10 kilometres. The team successfully transmitted photons in 7 of 14 attempts, generating quantum keys more than 800,000 bits long.

The authors say that this ‘uplink’ scheme, in which photons are generated at ground stations, could be simpler than a set-up used by rivals, which requires complex devices to be put into orbit.

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The Lighthouse/Universal Images Group/REX/Shutterstock

Computer science

Robot can single out humans

A robot can learn to detect human motion by the tell-tale smoothness with which people move.

To work with humans, robots must discriminate between movements of living and non-living things — a challenging task. Alessia Vignolo at the Italian Institute of Technology in Genoa and her team developed a machine-learning algorithm that exploits the characteristic smoothness with which humans change speed and trajectory on a split-second timescale.

By observing how sharply motion changed, the algorithm learned to differentiate between human actions, such as rolling dough, and the movements of inanimate objects, such as toy trains. The program does not interpret objects on the basis of their appearance, so it was successful even when viewing unfamiliar actions and when a scene was partly obscured.

Installed in a humanoid robot, the algorithm was able to automatically direct the machine’s gaze at humans, a useful skill for social interaction, say the authors.

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Auriga

Astronomy and astrophysics

How galaxies grew

Milky-Way-like galaxies formed through gentle mergers according to mega-simulations.

Large disk-shaped galaxies such as the Milky Way grow bigger when external gas and dark matter merge into them with just the right speed and trajectory.

A team led by Robert Grand at the Heidelberg Institute for Theoretical Studies in Germany created one of the largest cosmological simulations ever run, and used it to show how features such as the Milky Way’s spiral arms came to be. The results suggest that when material flows gently into a growing galaxy, it bulks up the central disk and allows structures such as bars and spiral arms to form. By contrast, violent collisions tend to shred the galaxy and limit its growth, say the authors.

The model ran on two supercomputers over several months and included, for the first time, the effects of magnetic fields that pervade interstellar space. Astronomers can compare the results of the simulations with their observations to better understand galaxy formation, says the team.

Zoology

Hunting spiders lose web skills

Adaptations to create sticky traps leaves ground spiders without a safety harness.

Ground spiders (Gnaphosidae) specialize in catching prey that fights back fiercely, including ants and other spiders. They snare their prey with an unusually glue-like silk, which evolved from a thread normally used to anchor a web’s structural silks to surfaces.

Jonas Wolff at Macquarie University in Sydney, Australia, and his colleagues studied 11 species in slow-motion video and examined the biomechanics of their silk and silk-producing structures.

The researchers found that as the gluey silk evolved into a hunting tool, the glands that produce it became bigger, while those that make the main thread shrank. As a result, these ground spiders can no longer spin abseiling ‘draglines’ and are barely able to attach webs to the environment.

Drug discovery

New class of antibiotic found

Natural compound kills bacteria that are resistant to multiple antibiotics.

Richard Ebright at Rutgers University in Piscataway, New Jersey, Stefano Donadio at the biotechnology firm Naicons in Milan, Italy, and their team extracted the antibiotic — called pseudouridimycin — from microbes in soil. They found that it cured bacterial infections in mice and killed several strains of antibiotic-resistant bacteria in culture.

The drug works by stopping bacteria from making RNA — it inhibits the binding of a nucleoside triphosphate, a building block of nucleic acids. Other antibiotics also stop RNA synthesis, but not by the same mechanism. This means that few bacteria will be prepared for pseudouridimycin’s mode of attack, say the authors.The team showed that resistance to pseudouridimycin develops ten times more slowly than it does to rifampin, an existing drug that also inhibits RNA synthesis.

Antiviral drugs that block nucleoside triphosphates have transformed the treatment of hepatitis C and HIV, add the authors, who hope that the new drug will be similarly successful against bacteria.

Cell biology

A UV-free tan that protects skin

Drug that stimulates melanin production could shield skin from damage caused by the Sun.

A drug that can be applied to the skin can boost production of the pigment melanin and potentially protect against cancer.

A type of melanin known as eumelanin darkens skin and helps to shield cells from damage caused by ultraviolet (UV) light, but drugs known to promote its production in mice struggle to penetrate the tougher barrier of human skin.

David Fisher of Massachusetts General Hospital in Boston and his colleagues therefore looked for alternatives. They focused on compounds that inhibit SIK, a protein involved in the suppression of pigment synthesis. One such compound was found to stimulate eumelanin production in mice that produce low levels of the pigment owing to a genetic mutation.

To increase the chances of penetrating human skin, the researchers developed SIK inhibitors that were smaller and more soluble in lipids than the original compound. Two of these increased eumelanin production in human skin cells. The researchers hope that the compounds might be useful in combination with sunscreens.

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Michael Cook/Altai World Photography/Getty

Ecology

How termite mounds begin

Collective digging, rather than depositing of soil, triggers mound building by termites.

No one knows for sure how termites collaborate to build complex structures, although researchers have long thought that a chemical, secreted by the creatures when they deposit soil, prompts others to start dropping soil in the same place.

Ben Green at Harvard University in Cambridge, Massachusetts, and his colleagues observed the behaviour of workers from two species of termite (Macrotermes) in soil-lined Petri dishes. Tracking the insects’ motion and behaviour, the researchers first observed random digging, after which termites clustered at the busiest excavation sites. Soil deposited at these sites became the basis for new mounds.

The observations fit with a simulation by the team in which mound building is initially driven by termites joining in at the most popular excavation sites; they fit less well, the authors say, with a model in which the insects deposit soil in response to a chemical signal.

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Ingrid Visser/Hedgehog House/Minden/NGC

Ecology

Sea-ice ‘treadmill’ speeds up for polar bears

Faster-drifting sea ice forces bears to travel farther for food.

Shrinking Arctic sea ice has already reduced the roaming range of polar bears (Ursus maritimus), but the impact of changes in ice drift has not been explored. George Durner at the US Geological Survey in Anchorage, Alaska, and his team analysed data on sea-ice drift across the Beaufort and Chukchi seas between 1987 and 2013, along with the movements of a total of 273 radio-tagged polar bears during that period. They found an increased rate of westward ice drift since 1987, which coincided with bears walking eastward faster or for longer to reach their seal-hunting grounds.

Bears would need to catch up to three more seals each year to fuel this extra activity, say the authors, who add that faster-drifting ice could exacerbate the physiological stress that bears already face in the warming Arctic.

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