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Top 10 Science Stories of 2015

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getty images

It’s been a busy year for scientists: medical breakthroughs; newly discovered human ancestors; genes and neurons; Earth’s troubled species; and enticing findings from Mars, Pluto, and beyond. Here are 10 science advances that made a big impact in 2015. 


After a 9.5-year, 3-billion-mile journey, NASA’s intrepid New Horizons spacecraft finally reached Pluto in July, sending back high-resolution images of the dwarf planet and its moon, Charon. At its closest approach, the craft passed within 7800 miles of Pluto’s surface—close enough to reveal bizarre ice mountains and vast, crater-free plains, seemingly divided into “cells” dozens of miles wide. There’s evidence of geological activity within the last 100 million years—a mere eye-blink compared to the age of the solar system—which came as a surprise to scientists, who imagined Pluto to be a geologically “dead” world. Charon, meanwhile, has cliffs that run for hundreds of miles, and canyons more than six miles deep. The findings will keep planetary scientists busy for years.


An organism’s development is governed by its DNA—but what if you could manipulate that DNA at will? The era of custom “gene editing” now looms on the horizon, thanks to a tool known as CRISPR-Cas9, which allows researchers to “swap out” sections of a genome faster and more cheaply than ever before. Earlier this year, scientists developed gene-edited mosquitos that are resistant to malaria and gene-edited African pigs that are immune to swine fever; the FDA, meanwhile, recently approved a fast-growing, gene-edited salmon for human consumption.

Are genetically engineered humans next? Scientists in China have already done the first experiments on human embryos, in a bid to correct faulty genes that cause disease. The embryos in those studies were non-viable, but even so there’s been a storm of controversy. Some argue in favor of human gene modification, in the hope of engineering human beings with less susceptibility to devastating illnesses such as cancer and dementia—while others see any such research as the start of a slippery slope leading to a world divided between genetic haves and have-nots.


Berger et al. ineLife.

Pieced together from 1500 bones found deep in a cave near Johannesburg, South Africa, Homo naledi—claimed to represent a new species of human ancestor—caused a sensation when the finding was announced in September. (“Naledi” means “star” in Sesotho, one of South Africa’s official languages.) Its bones tell a complicated story. The small skull and ape-like shoulders suggest it may be among the earliest members of the human family tree, while the shape of the feet and ankles indicate it walked upright. And yet the highly curved fingers hint at the tree-climbing prowess of its ancestors.

But is it really a new species? Some skeptics believe the bones could belong to early members of Homo erectus, a well-documented human ancestor that lived from about 1.9 million years ago to about 70,000 years ago—or even an isolated offshoot of Homo sapiens. It would help if we knew exactly when Homo naledi flourished; unfortunately, scientists haven’t been able to date the bones yet.


Over the past 450 million years, the Earth has witnessed five “mass extinction events”—catastrophes in which an asteroid impact or volcanic activity triggered rapid climatic change and a dramatic loss of biodiversity. The most severe of these was the event that killed off the dinosaurs—and three-quarters of all species—some 66 million years ago. Scientists believe we’re now on the brink of a sixth such mass extinction event—only this time, the culprit is human activity. In a study published in the journal Science Advances in June, biologists found that our planet is losing animal species at 20 to 100 times the average “background” rate, and that the rate is increasing. “The smoking gun in these extinctions is very obvious, and it’s in our hands,” Todd Palmer, a biologist at the University of Florida and a co-author of the study, told the Washington Post


Injecting drugs into the body is routine—unless you’re targeting the brain, which is protected by the “blood-brain barrier,” a film-like coating that surrounds the blood vessels in the brain. The barrier prevents harmful substances from entering the brain—but also stands in the way of certain treatments (for example, chemotherapy drugs targeting brain tumors). In November, doctors in Toronto used tightly focused ultrasound waves to penetrate the barrier for the first time. The technique could pave the way for the treatment of an array of illnesses, from brain cancer to Alzheimer’s disease. 


Getty Images

Mars, with its many similarities to Earth, has long been the most enigmatic planet in our solar system—and it became even more beguiling in September, when NASA scientists announced that they’d found evidence for flowing water on the planet’s surface. Images from the Mars Reconnaissance Orbiter reveal dark streaks that appear during the Martian summer, likely the result of seasonal “flows.” A caveat: the water is briny and extremely salty, and scientists are far from certain that it’s capable of supporting life. And while it would be great to go there (or send a robotic ambassador) for a close-up view, there’s a very real danger of contaminating the area with microbes from Earth.


It’s one of the most bizarre features of the quantum world: The notion that two particles, even if they’re far apart, can be “entangled” quantum mechanically. When two particles are entangled, measuring the properties of one particle instantly gives you information about the other, regardless of the distance between them. The notion of entanglement dates back to a paper written by Einstein and two colleagues in the 1930s, although he later dismissed the idea as “spooky action at a distance.” But beginning in the late '70s, ever-more sophisticated experiments suggested entanglement is real. In October, physicists in the Netherlands managed to entangle two electrons almost a mile apart—and they say they’ve ruled out all of the loopholes which made earlier experiments inconclusive. And while it all may sound pie-in-the-sky, scientists say that the research could eventually lead to the development of ultra-fast “quantum computers,” with potentially game-changing applications in medicine, cryptography, and artificial intelligence.



We think of memories like pages in a scrapbook, or pictures in a photo album, but in practice, our memories are often wrong. “False memory syndrome” is now recognized as a real phenomenon in the scientific literature, and psychologists are eager to learn more about how erroneous memories form. Animal studies may shed some light. In March, neuroscientists in France described how they were able to implant false memories into mice while the animals slept. They used electrodes to directly stimulate specific nerve cells within the brain, causing the mice to associate certain locations with rewards. After waking, the mice “remembered” those associations, spending more time in the locations where they (incorrectly) recalled receiving a reward. The researchers hope their work will help explain how false beliefs form in humans.


We don’t usually think of events in deep space influencing life on Earth—after all, astrology was debunked centuries ago. But if physicist Lisa Randall is right, there may be a subtle but important connection between an exotic form of matter that permeates the universe, and the evolution of life on our blue-green world. In her book Dark Matter and the Dinosaurs, Randall suggests that a thin disk of dark matter—a kind of matter that responds to gravity, but not to light—might periodically perturb the orbit of comets at the far edges of our solar system. That might be what happened 66 million years ago, when a wayward comet is believed to have slammed into the Earth, triggering catastrophic climate change and dooming not only the dinosaurs but three-quarters of all species. It’s a controversial theory, but it could gain support, Randall says, if we can detect the gravitational influence of the alleged dark-matter disk. Read an excerpt from Dark Matter and the Dinosaurs on Science Friday.


Artist's representation of a crumbling Dyson sphere orbiting KIC 8462852. Image credit: Danielle Futselaar // SETI International

You wouldn’t think it’s anything special from its name—KIC 8462852—but the peculiar star, located about 1500 light-years from Earth, set the Internet abuzz in September when it was suggested that it might be home to an advanced alien civilization (“might” being the key word, of course). Data from the Kepler space telescope showed that the star undergoes strange variations in brightness over time. Kepler is specifically designed to detect planets that may periodically pass in front of a star, causing it to dim—but KIC 8462 displayed a more unusual pattern, with more substantial dimming at irregular intervals. A swarm of comets was said to be the most likely explanation. But one of the astronomers also suggested the possibility of an “alien megastructure”—perhaps some variation of the “Dyson sphere,” a vast artificial structure that an advanced civilization might build surrounding a star, popularized by physicist Freeman Dyson in the 1960s.

Later, radio astronomers aimed the Allen Telescope Array in California at the star, just in case it was emitting alien chatter. It was not. The latest thinking is that it’s probably comets after all. The lesson? When it’s a choice between aliens and something else, it’s always been something else (so far), and that’s most likely the case this time. But for getting people’s attention, little green men beat icy snowballs every time. 

Penn Vet Working Dog Center
Stones, Bones, and Wrecks
New Program Trains Dogs to Sniff Out Art Smugglers
Penn Vet Working Dog Center
Penn Vet Working Dog Center

Soon, the dogs you see sniffing out contraband at airports may not be searching for drugs or smuggled Spanish ham. They might be looking for stolen treasures.

K-9 Artifact Finders, a new collaboration between New Hampshire-based cultural heritage law firm Red Arch and the University of Pennsylvania, is training dogs to root out stolen antiquities looted from archaeological sites and museums. The dogs would be stopping them at borders before the items can be sold elsewhere on the black market.

The illegal antiquities trade nets more than $3 billion per year around the world, and trafficking hits countries dealing with ongoing conflict, like Syria and Iraq today, particularly hard. By one estimate, around half a million artifacts were stolen from museums and archaeological sites throughout Iraq between 2003 and 2005 alone. (Famously, the craft-supply chain Hobby Lobby was fined $3 million in 2017 for buying thousands of ancient artifacts looted from Iraq.) In Syria, the Islamic State has been known to loot and sell ancient artifacts including statues, jewelry, and art to fund its operations.

But the problem spans across the world. Between 2007 and 2016, U.S. Customs and Border Control discovered more than 7800 cultural artifacts in the U.S. looted from 30 different countries.

A yellow Lab sniffs a metal cage designed to train dogs on scent detection.
Penn Vet Working Dog Center

K-9 Artifact Finders is the brainchild of Rick St. Hilaire, the executive director of Red Arch. His non-profit firm researches cultural heritage property law and preservation policy, including studying archaeological site looting and antiquities trafficking. Back in 2015, St. Hilaire was reading an article about a working dog trained to sniff out electronics that was able to find USB drives, SD cards, and other data storage devices. He wondered, if dogs could be trained to identify the scents of inorganic materials that make up electronics, could they be trained to sniff out ancient pottery?

To find out, St. Hilaire tells Mental Floss, he contacted the Penn Vet Working Dog Center, a research and training center for detection dogs. In December 2017, Red Arch, the Working Dog Center, and the Penn Museum (which is providing the artifacts to train the dogs) launched K-9 Artifact Finders, and in late January 2018, the five dogs selected for the project began their training, starting with learning the distinct smell of ancient pottery.

“Our theory is, it is a porous material that’s going to have a lot more odor than, say, a metal,” says Cindy Otto, the executive director of the Penn Vet Working Dog Center and the project’s principal investigator.

As you might imagine, museum curators may not be keen on exposing fragile ancient materials to four Labrador retrievers and a German shepherd, and the Working Dog Center didn’t want to take any risks with the Penn Museum’s priceless artifacts. So instead of letting the dogs have free rein to sniff the materials themselves, the project is using cotton balls. The researchers seal the artifacts (broken shards of Syrian pottery) in airtight bags with a cotton ball for 72 hours, then ask the dogs to find the cotton balls in the lab. They’re being trained to disregard the smell of the cotton ball itself, the smell of the bag it was stored in, and ideally, the smell of modern-day pottery, eventually being able to zero in on the smell that distinguishes ancient pottery specifically.

A dog looks out over the metal "pinhweel" training mechanism.
Penn Vet Working Dog Center

“The dogs are responding well,” Otto tells Mental Floss, explaining that the training program is at the stage of "exposing them to the odor and having them recognize it.”

The dogs involved in the project were chosen for their calm-but-curious demeanors and sensitive noses (one also works as a drug-detection dog when she’s not training on pottery). They had to be motivated enough to want to hunt down the cotton balls, but not aggressive or easily distracted.

Right now, the dogs train three days a week, and will continue to work on their pottery-detection skills for the first stage of the project, which the researchers expect will last for the next nine months. Depending on how the first phase of the training goes, the researchers hope to be able to then take the dogs out into the field to see if they can find the odor of ancient pottery in real-life situations, like in suitcases, rather than in a laboratory setting. Eventually, they also hope to train the dogs on other types of objects, and perhaps even pinpoint the chemical signatures that make artifacts smell distinct.

Pottery-sniffing dogs won’t be showing up at airport customs or on shipping docks soon, but one day, they could be as common as drug-sniffing canines. If dogs can detect low blood sugar or find a tiny USB drive hidden in a house, surely they can figure out if you’re smuggling a sculpture made thousands of years ago in your suitcase.

New Cancer-Fighting Nanobots Can Track Down Tumors and Cut Off Their Blood Supply

Scientists have developed a new way to cut off the blood flow to cancerous tumors, causing them to eventually shrivel up and die. As Business Insider reports, the new treatment uses a design inspired by origami to infiltrate crucial blood vessels while leaving the rest of the body unharmed.

A team of molecular chemists from Arizona State University and the Chinese Academy of Sciences describe their method in the journal Nature Biotechnology. First, they constructed robots that are 1000 times smaller than a human hair from strands of DNA. These tiny devices contain enzymes called thrombin that encourage blood clotting, and they're rolled up tightly enough to keep the substance contained.

Next, researchers injected the robots into the bloodstreams of mice and small pigs sick with different types of cancer. The DNA sought the tumor in the body while leaving healthy cells alone. The robot knew when it reached the tumor and responded by unfurling and releasing the thrombin into the blood vessel that fed it. A clot started to form, eventually blocking off the tumor's blood supply and causing the cancerous tissues to die.

The treatment has been tested on dozen of animals with breast, lung, skin, and ovarian cancers. In mice, the average life expectancy doubled, and in three of the skin cancer cases tumors regressed completely.

Researchers are optimistic about the therapy's effectiveness on cancers throughout the body. There's not much variation between the blood vessels that supply tumors, whether they're in an ovary in or a prostate. So if triggering a blood clot causes one type of tumor to waste away, the same method holds promise for other cancers.

But before the scientists think too far ahead, they'll need to test the treatments on human patients. Nanobots have been an appealing cancer-fighting option to researchers for years. If effective, the machines can target cancer at the microscopic level without causing harm to healthy cells. But if something goes wrong, the bots could end up attacking the wrong tissue and leave the patient worse off. Study co-author Hao Yan believes this latest method may be the one that gets it right. He said in a statement, "I think we are much closer to real, practical medical applications of the technology."

[h/t Business Insider]


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