Author Archives: Attention to the Unseen
It’s official: Timeline for human migration gets a rewrite
Gemma Tarlach writes: The great thing about science is supposed to be that you come up with a hypothesis and then you and other researchers try to shoot it down and, if the hypothesis doesn’t hold up, you come up with a new one based on what you learned from destroying the old one. And the scientific method generally works, as long as everyone keeps their egos in check.
Unfortunately, many researchers clung to the idea of a single migration out of Africa, no earlier than 60,000 years ago, for too long. Finds such as a human presence in the Levant 100,000 years ago, for example, were dismissed as a single band of early humans that strayed too far from home and went extinct— in other words, an evolutionary dead end.
Today, however, writing in Science, researchers say that no one can ignore the preponderance of evidence. It’s time, at long last, to revise that tired old timeline of human migration.
The timeline they call for is one of multiple migrations out of Africa beginning perhaps 120,000 years ago. While some of these early explorations certainly failed and became evolutionary dead ends, others, say the authors, survived, not only spreading across Asia but interbreeding with Denisovans and Neanderthals.
Both the archaeological and genetic evidence support a large dispersal from Africa around 60,000 years ago, but it was by no means the first — or the last — to occur. [Continue reading…]
Music: Amber Navran — ‘Lastaya Love’
Matter inside a neutron star is so dense that a teaspoonful would weigh a billion tons
Science News reports: On astrophysicists’ charts of star stuff, there’s a substance that still merits the label “here be dragons.” That poorly understood material is found inside neutron stars — the collapsed remnants of once-mighty stars — and is now being mapped out, as scientists better characterize the weird matter.
The detection of two colliding neutron stars, announced in October (SN: 11/11/17, p. 6), has accelerated the pace of discovery. Since the event, which scientists spied with gravitational waves and various wavelengths of light, several studies have placed new limits on the sizes and masses possible for such stellar husks and on how squishy or stiff they are.
“The properties of neutron star matter are not very well known,” says physicist Andreas Bauswein of the Heidelberg Institute for Theoretical Studies in Germany. Part of the problem is that the matter inside a neutron star is so dense that a teaspoonful would weigh a billion tons, so the substance can’t be reproduced in any laboratory on Earth.
In the collision, the two neutron stars merged into a single behemoth. This remnant may have immediately collapsed into a black hole. Or it may have formed a bigger, spinning neutron star that, propped up by its own rapid rotation, existed for a few milliseconds — or potentially much longer — before collapsing. The speed of the object’s demise is helping scientists figure out whether neutron stars are made of material that is relatively soft, compressing when squeezed like a pillow, or whether the neutron star stuff is stiff, standing up to pressure. This property, known as the equation of state, determines the radius of a neutron star of a particular mass. [Continue reading…]
Music: Moonchild — ‘Run Away’
Music: Amber Navran — ‘Letter 7/Say Yes’
An excerpt from Letter 7 written by Rainer Maria Rilke in 1902:
For one human being to love another, this is perhaps the most difficult of all our tasks, the ultimate, the last test and proof, the work for which all other work is but preparation. For this reason young people, who are beginners in everything, cannot yet know love: they have to learn it.
But young people err so often and so grievously in this: that they (in whose nature it lies to have no patience) fling themselves at each other when love takes possession of them, scatter themselves, just as they are, in all their untidiness, disorder, confusion…. and then what? What is life to do with this heap of half-battered existence which they call their communion and which they would gladly call their happiness
‘Let the soul dangle’: How mind-wandering spurs creativity
By Julia Christensen, Guido Giglioni, and Manos Tsakiris
The Renaissance painter Albrecht Dürer was regarded by his friends as a master in the art of mind-wandering. He could become ‘enwrapped’ in his own pleasant reflections, wrote the German humanist Willibald Pirckheimer, at which times Dürer ‘would seem the happiest person on Earth’.
Many of us are familiar with mind-wandering in a number of guises: procrastination, reflection, meditation, self-flagellation, daydreaming. But while some mental meandering seems fruitful, on other occasions it has the unmistakeable bite of a bad habit, something that holds us back from reaching our full potential. Reverie can be a reprieve from reality and a font of inspiration, yes. But equally familiar is the mind’s tendency to devolve into sour and fruitless rumination when left to its own devices, especially when we’re in the grip of depression, anxiety or obsession.
Can art itself be a useful catalyst for nudging us towards more helpful emotions and mental states? Whether in the form of literature, rap or abstract oil painting, many of us know we can improve the tenor of our thoughts by contemplating art. The Germans have a lovely saying for the benefits of keeping an idle (or idling) mind: ‘die Seele baumeln lassen’, meaning ‘let the soul dangle’. Now, the emerging science of neuroaesthetics is beginning to reveal the biological processes that sit behind such ‘dangling’.
Music: Moonchild — ‘Ocean Deep’
What the Pliocene epoch can teach us about future warming on Earth
Science News reports: Imagine a world where the polar ice sheets are melting, sea level is rising and the atmosphere is stuffed with about 400 parts per million of carbon dioxide. Sound familiar? It should. We’re living it. But the description also matches Earth a little over 3 million years ago, in the middle of the geologic epoch known as the Pliocene.
To understand how our planet might respond as global temperatures rise, scientists are looking to warm periods of the past. These include the steamy worlds of the Cretaceous Period, such as around 90 million years ago, and the boundary of the Paleocene and Eocene epochs, about 56 million years ago.
But to many researchers, the best reference for today’s warming is the more recent Pliocene, which lasted from 5.3 million to 2.6 million years ago. The mid-Pliocene was the last time atmospheric CO2 levels were similar to today’s, trapping heat and raising global temperatures to above the levels Earth is experiencing now.
New research is illuminating how the planet responded to Pliocene warmth. One set of scientists has fanned out across the Arctic, gathering geologic clues to how temperatures there may have been as much as 19 degrees Celsius higher than today. The warmth allowed trees to spread far to the north, creating Arctic forests where three-toed horses, giant camels and other animals roamed. When lightning struck, wildfires roared across the landscape, spewing soot into the air and altering the region’s climate.
Other researchers are pushing the frontiers of climate modeling, simulating how the oceans, atmosphere and land responded as Pliocene temperatures soared. One new study shows how the warmth may have triggered huge changes in ocean circulation, setting up an enormous overturning current in the Pacific Ocean, similar to the “conveyor belt” in today’s Atlantic that drives weather and climate. A second new paper suggests that the Greenland and Antarctic ice sheets might have responded differently to Pliocene heat, melting at different times.
All this research into the last great warm period is helping scientists think more deeply about how the future might play out. It may not be a road map to the next 100 years, but the Pliocene is a rough guide to the high sea levels, vanishing ice and altered weather patterns that might arrive hundreds to thousands of years from now.
“It’s a case study for understanding how warm climates function,” says Heather Ford, a paleoceanographer at the University of Cambridge. “It’s our closest analog for future climate change.” [Continue reading…]
Music: Moonchild — ‘Cure’
America’s ancient heritage is rapidly disappearing
Kathleen Sharp writes: Like many pre-Columbian sites on this timeless plateau [in Arizona], Little Giant’s Chair is both a Hopi shrine and a crime scene. America’s ancient heritage is disappearing at an alarming rate. Some archaeologists estimate that more than half of America’s historic sites have been vandalized or looted. According to the non-profit Saving Antiquities for Everyone, over 90 percent of known American Indian archaeological sites have been destroyed or degraded by looters.
As the cultural legacy of Native American tribes has vanished, the demand for genuine U.S. antiquities has exploded. And few objects are more coveted than a Hopi religious item, Kuwanwisiwma says. “People love them so much, they are slowly robbing us to death.”
The outside world calls them “artifacts,” but they are often ceremonial items that have been passed down over the years and are still in use by the tribes. Others are ripped from grave sites like the one at Little Giant’s Chair. If this burial ground had been in Arlington, Virginia, or Gettysburg, Pennsylvania, the police would have wrapped the scene in yellow crime tape and called in their top investigators. But on this case, the primary detectives were a Hopi ranger and the skeleton crew at the CPO, whose mission is to find, repatriate, and protect the cultural objects that belong to the Hopi people. [Continue reading…]
Music: Lonnie Smith ft. George Benson — ‘It’s Changed’
How bacteria help regulate blood pressure
Veronique Greenwood writes: Some years ago, when Jennifer Pluznick was nearing the end of her training in physiology and sensory systems, she was startled to discover something in the kidneys that seemed weirdly out of place. It was a smell receptor, a protein that would have looked more at home in the nose. Given that the kidneys filter waste into urine and maintain the right salt content in the blood, it was hard to see how a smell receptor could be useful there. Yet as she delved deeper into what the smell receptor was doing, Pluznick came to a surprising conclusion: The kidney receives messages from the gut microbiome, the symbiotic bacteria that live in the intestines.
In the past few years, Pluznick, who is now an associate professor of physiology at Johns Hopkins University, and a small band of like-minded researchers have put together a picture of what the denizens of the gut are telling the kidney. They have found that these communiqués affect blood pressure, such that if the microbes are destroyed, the host suffers. The researchers have uncovered a direct, molecular-level explanation of how the microbiome conspires with the kidneys and the blood vessels to manipulate the flow of blood.
The smell receptor, called Olfr78, was an orphan at first: It had previously been noticed in the sensory tissues of the nose, but no one knew what specific scent or chemical messenger it responded to. Pluznick began by testing various chemical possibilities and eventually narrowed down the candidates to acetate and propionate. These short-chain fatty acid molecules come from the fermentation breakdown of long chains of carbohydrates — what nutritionists call dietary fiber. Humans, mice, rats and other animals cannot digest fiber, but the bacteria that live in their guts can.
As a result, more than 99 percent of the acetate and propionate that floats through the bloodstream is released by bacteria as they feed. “Any host contribution is really minimal,” Pluznick said. Bacteria are therefore the only meaningful source of what activates Olfr78 — which, further experiments showed, is involved in the regulation of blood pressure. [Continue reading…]
The scallop sees its world with hundreds of space-age eyes
Carl Zimmer writes: It’s hard to see what’s so special about a scallop. It looks a lot like a clam, mussel or any other bivalve. Inside its hinged shell lurks a musclebound creature that’s best enjoyed seared in butter.
But there’s something more to this ubiquitous entree: the scallop sees its world with hundreds of eyes. Arrayed across the opening of its shell, the eyes glitter like an underwater necklace. Each sits at the tip of its own tentacle and can be extended beyond the rim of the shell.
While some invertebrate eyes can sense only light and dark, scientists have long suspected that scallops can make out images, perhaps even recognizing predators quickly enough to jet away to safety. But scallop eyes — each about the size of a poppy seed — are so tiny and delicate that scientists have struggled to understand how they work.
Now, a team of Israeli researchers has gotten a look at the hidden sophistication of the scallop eye, thanks to powerful new microscopes. On Thursday, they reported in the journal Science that each eye contains a miniature mirror made up of millions of square tiles. The mirror reflects incoming light onto two retinas, each of which can detect different parts of the scallop’s surroundings.
Our own eye has been likened to a camera: it uses a lens to focus light on the retina. The new research suggests that scallop eyes are more akin to another kind of technology: a reflector telescope of the sort first invented by Newton. Today, astronomers build gigantic reflector telescopes to look in deep space, and they also build their mirrors out of tiles.
“For me, Newton and Darwin come together in these eyes,” said Gáspár Jékely, a neuroscientist at the University of Exeter who was not involved in the new study. [Continue reading…]
Music: Kelan Phil Cohran and Legacy — ‘White Nile’
Music: Arve Henriksen — ‘Blue Silk’
Music: Arve Henrikson — ‘Le Cimetière Marin’
Bacteria from outer space rendezvous with Russians at International Space Station?
National Geographic reports: Living bacteria have been found on the outside of the International Space Station, a Russian cosmonaut told the state news agency TASS this week.
Anton Shkaplerov, who will lead Russia’s ISS crew in December, said that previous cosmonauts swabbed the station’s Russian segment during spacewalks and sent the samples back to Earth. The samples came from places on the station that had accumulated fuel waste, as well as other obscure nooks and crannies. Their tests showed that the swabs held types of bacteria that were not on the module when it originally launched into orbit, Shkaplerov says.
In his interview with TASS, Shkaplerov says the bacteria “have come from outer space and settled along the external surface”—a claim that sparked some media outlets to issue frenzied reports about aliens colonizing the space station.
For now, though, details about the swabbing experiment are thin on the ground. Shkaplerov did not note whether the study has been vetted by a peer-reviewed journal, which means it’s unclear exactly when and how the full experiment was conducted, or how the team avoided any contamination from much more mundane bacteria on the cosmonauts or in the Earth-bound lab. Interview requests with the Russian space agency were unanswered when this article went to press.
Rather than microbes raining down from outer space, it’s much more plausible that the outside of the space station became contaminated by earthly organisms, many of which can survive in the harsh environment in orbit. [Continue reading…]
Indeed, the journey along Occam’s Razor is much shorter and vastly easier than any voyage from distant worlds.