News and Notes About Science
Posted May 21, 2018 5:04 p.m. EDT
In a Child’s Mummified Hand, a Coin for the Ferryman
At first, János Balázs had no idea why the tiny hand he found in a storage box of bones was green and mummified.
It was around 2005 and he was examining remains from an earlier archaeological dig of a cemetery conducted at Nyárlőrinc, a village in southern Hungary. The excavations had yielded more than 500 graves that mostly dated from between the 12th and 16th centuries. But none of those burials was anything like the mummified green hand Balázs and his colleague, Zoltán Bölkei, had uncovered in that forgotten box.
More than a decade later, Balázs and his colleagues think they have solved the mystery, and in doing so uncovered a unique form of mummification. They published their results recently in Archaeological and Anthropological Sciences.
The bones Balázs found were so small they could have been confused with a rat’s.
The remains are on display at Hungary’s Móra Ferenc Museum.
From inspecting the tiny skeleton, Balázs determined the deceased was either a stillbirth or premature baby that died shortly after birth.
Bronze or copper jewelry can often discolor skeletons as they degrade, and Balázs thought the child’s body came in contact with some sort of metal. But how did that mystery metal object end up near its tiny hands?
“It’s not so obvious, and it’s so unlikely that you’re questioning yourself,” Balázs, who is now a biological anthropologist at the University of Szeged, said through his colleague and translator Zsolt Bereczki, who is also a biological anthropologist and author on the paper.
They performed a chemical analysis on the remains and found that the child had copper levels that were hundreds of times more than average.
Balázs soon discovered that a nearby museum also had storage boxes from the dig where the baby was found. When he examined the boxes, he found the clues he needed: a small ceramic pot and a corroded copper coin.
The team concluded that before the child was placed in the pot and buried, someone put the copper coin into its hand. Many cultures in antiquity have buried their dead with coins as a way to pay a mythical ferryman to take their souls into the afterlife.
In his case, the copper’s antimicrobial properties protected the child’s hand from decay.
— NICHOLAS ST. FLEUR
In Virtual Reality, How Much Body Do You Need?
How connected are your body and your consciousness?
When Michiteru Kitazaki, a professor of engineering at Toyohashi University of Technology in Japan, recently posed this question in an email, he evoked an idea from Japanese culture known as tamashii, or the soul without a body.
Will it soon be possible, he wondered, to simulate the feeling of a spirit not attached to any particular physical form using virtual or augmented reality?
If so, a good place to start would be to figure out the minimal amount of body we need to feel a sense of self, especially in digital environments where more and more people may find themselves for work or play. It might be as little as a pair of hands and feet, report Kitazaki and a Ph.D. student, Ryota Kondo.
In a paper published recently in Scientific Reports, they showed that animating virtual hands and feet alone is enough to make people feel their sense of body drift toward an invisible avatar.
Their work fits into a corpus of research on illusory body ownership, which has challenged understandings of perception and contributed to therapies like treating pain for amputees who experience phantom limb.
The original body ownership trick was the rubber-hand illusion. In the 1990s, researchers found that if they hid a person’s actual hand behind a partition, placed a rubber hand in view next to it and repeatedly tapped and stroked the real and fake hand in synchrony, the subject would soon eerily start to feel sensation in the rubber hand.
Today, technologists working on virtual reality are using modern-day riffs on the rubber-hand illusion to understand how users will adjust when presented with digital bodies that do not match their own.
Taking ownership of an invisible body in cyberspace or otherwise could have positive applications, like reducing social anxiety, Kitazaki said.
Using an Oculus Rift virtual reality headset and a motion sensor, Kitazaki’s team performed a series of experiments in which volunteers watched disembodied hands and feet move 2 meters in front of them in a virtual room. In one experiment, when the hands and feet mirrored the participants’ own movements, people reported feeling as if the space between the appendages were their own bodies.
— STEPH YIN
Scientists Made Snails Remember Something That Never Happened to Them
In a paper published recently in the journal eNeuro, scientists at the University of California, Los Angeles, reported that when they transferred molecules from the brain cells of trained snails to untrained snails, the animals behaved as if they remembered the trained snails’ experiences.
David Glanzman, a professor of neurobiology at UCLA who is an author of the new paper, has been studying Aplysia californica, a sea snail,and its ability to make long-term memories for years. The snails, which are about 5 inches long, are a useful organism for studying how memories are formed because their neurons are large and relatively easy to work with.
In experiments by Glanzman and colleagues, when these snails get a little electric shock, they briefly retract their frilly siphons, which they use for expelling waste. A snail that has been shocked before, however, retracts its siphon for much longer than a new snail recruit.
Recently, the scientists realized that even when they interfered with their trained snails’ brain cells in a way that should have removed the memory completely, some vestige remained. They decided to see whether something beyond the brain cells’ connections to each other — namely, RNA — could be hanging on to the memory.
The researchers first extracted all the RNA from the brain cells of trained snails, and injected it into new snails. To their surprise, the new snails kept their siphons wrapped up much longer after a shock, almost as if they’d been trained.
Next, the researchers took the brain cells of trained snails and untrained snails and grew them in the lab. They bathed the untrained neurons in RNA from trained cells, then gave them a shock, and saw that they fired in the same way that trained neurons do. The memory of the trained cells appeared to have been transferred to the untrained ones.
Importantly, when the researchers gave the new snails a drug that keeps chemical tags from being added to DNA, the memory did not transfer. That is in line with other experiments that have suggested that blocking the formation of such tags blocks the formation of long-term memory in snails and some rodents, said Glanzman. That suggests that what they are seeing is in fact related to memory, and not something else to do with the influx of new RNA.
— VERONIQUE GREENWOOD
A Very Hungry Black Hole Is Found, Gorging on Stars
It is a truism of modern astronomy that every galaxy has a hungry heart, to paraphrase Bruce Springsteen, in the form of a massive black hole gulping gas, dust and even stars.
Astronomers in Australia now say they have found the hungriest heart in all the cosmos. It is a black hole 20 billion times the mass of the sun eating the equivalent of a star every two days.
The black hole is growing so rapidly, said Christian Wolf, of the Australian National University, who led the team that found it in the depths of time, “that it is probably 10,000 times brighter than the galaxy it lives in.” So bright, that it is dazzling our view and we can’t see the galaxy itself. He and his colleagues announced the discovery in a paper that was to be published in the Publications of the Astronomical Society of Australia.
Black holes are a one-way gate to gravitational oblivion, according to Einstein’s theory of general relativity, but they can only swallow so much, depending on their size; the rest of the matter and energy gets splashed out across space, producing the fireworks popularly known as quasars.
The blaze from material swirling around this newly observed drainpipe into eternity — known officially as SMSS J215728.21-360215.1 — is as luminous as 700 trillion suns, according to Wolf and his collaborators. If it were at the center of our own galaxy, the Milky Way, it would be 10 times brighter than the moon and bathe the Earth in so many X-rays that life would be impossible.
Luckily it’s not anywhere nearby. It is in fact 12 billion light years away, which means it took that long for its light to reach us, so we are glimpsing this cataclysm as it appeared at the dawn of time, only 2 billion years after the Big Bang, when stars and galaxies were furiously forming.
How it got so big so quickly after the Big Bang adds to a mystery about the origin of the supermassive black holes that occupy the centers of galaxies. What came first? The black holes or the galaxies?
“How they grew to such mass so early after the Big Bang is a profound puzzle for physics,” the authors say in their paper.
— DENNIS OVERBYE
The Thing Inside Your Cells That Might Determine How Long You Live
Once there was a mutant worm in an experiment. It lived for 46 days. This was much longer than the oldest normal worm, which lived just 22.
Researchers identified the mutated gene that had lengthened the worm’s life, which led to a breakthrough in the study of aging — it seemed to be controlled by metabolic processes. Later, as researchers studied these processes, all signs seemed to point to the nucleolus.
Under a microscope, it is hard to miss. Take just about any cell, find the nucleus, then look inside it for a dark, little blob. That’s the nucleolus.
You’ve got one in every nucleus of every cell in your body, too. All animals do. So do plants, and yeast — and anything with a cell with a nucleus. And they’ve become much more important in our understanding of how cells work.
“We think the nucleolus plays an important role in regulating the life span of animals,” said Adam Antebi, a cellular biologist at the Max Planck Institute for Biology of Ageing in Germany. He’s an author of a new review published in Trends in Cell Biology that examines all the new ways that researchers have fallen in love with the nucleolus — especially its role in aging.
The nucleolus is the cell’s ribosome factory. Ribosomes are like micro-machines that make proteins that cells then use for purposes like building walls, forming hairs, making memories, communicating, and starting, stopping and slowing down reactions that help a cell stay functioning.
But there’s more to the nucleolus than just making ribosomes.
If building a cell were like building a building, and the DNA contained the blueprint, the nucleolus would be the construction manager or engineer. “It knows the supply chain, coordinates all the jobs of building, does quality control checks and makes sure things continue to work well,” Antebi said.
How well it balances these tasks influences a cell’s health and life span. And in certain cells, its size has something to do with it.
The nucleolus can wax and wane in response to a body’s available nutrients and growth signals.
— JOANNA KLEIN