Barnes Ice Cap sits on the central plateau of Baffin Island, in the Canadian Arctic. It is the last surviving fragment of the Laurentide Ice Sheet, the largest of the Pleistocene ice sheets, which at its peak buried most of Canada under two miles of ice and locked away around 80 meters of sea level. That remnant has now yielded direct physical evidence that ice sheets might have reversed their retreat and started to grow again thousands of years ago.

In a recent Science study, researchers show that the Laurentide reached its smallest size about 3,600 years ago, then started re-expanding roughly 2,000 years ago, which the team interprets as the opening move of the next glaciation. Apparently, this brand-new ice age was on its way until about 1960, when human-caused climate warming reversed it.

Frozen to the bed

“Barnes is the last remaining piece of one of the domes of the Laurentide Ice Sheet,” says Nicolás Young, a geologist at Columbia University's Lamont-Doherty Earth Observatory and lead author of the study. As that enormous dome thinned through the Holocene, its margin withdrew up onto Baffin Island, and what's left today is the deflated core of something that was once two miles thick. The reason Barnes can testify about its own history, Young explains, comes down to the temperature at its base.

Read full article

Comments

Much of what we know about how a brain makes decisions comes from studying monkeys watching dots. In a task known as a random-dot-motion task, a cloud of flickering specks drifts weakly in one direction while the subject tries to determine whether—and in which direction— it’s moving. The task has shown that in the primate neocortex, neurons gather visual evidence over time, with their firing rates climbing until they cross a threshold, when the animal commits to a decision.

But avian brains don’t have a neocortex, so it wasn’t obvious how they made similar decisions.

“This was the big question,” said Andreas Nieder, a neurobiologist at the University of Tübingen. “How [would] a differently organized avian brain encode decisions?”

Read full article

Comments

One reason plastics are used so often is that they’re chemically inert, meaning bags, food containers, and cups don't react with what we put in them. Yet they can still break down into microplastics, which turn up in drinking water, human blood, arteries, and brains. The consequences of that are uncertain.

“Whether microplastics can directly cause human disease is still being researched,” said Wei Min, a chemist at Columbia University. In a new Nature study, Min's team took a step toward answering this question by demonstrating that microplastics are likely not as chemically inert as we might expect.

Microdroplet chemistry

Min's lab has spent years working on microdroplet chemistry, studying how water broken into tiny droplets behaves at its boundary with air. These droplets have been reported to generate reactive oxygen species, or ROS, a family of harmful, oxygen-containing molecules. “ROS will essentially bump into proteins, lipids, DNA, and cause damage,” Min said. “You could break a DNA strand into segments. You could mutate DNA; you could misfold proteins.”

Read full article

Comments

For about a decade, the mainstream understanding has been that psychedelics cause chaos in the brain. Brain networks—the stable patterns of communication that handle vision, attention, or our sense of self, and more—loosen and start talking to each other all at once. EEG traces get noisier and more complex. “Think of the networks of the brain as highways,” says Devon Stoliker, a neuroscientist at Monash University. “Under psychedelics, these highways break down into many different directions.”

In a recent Nature study, Stoliker’s team designed an experiment to test whether these directions are truly chaotic and random. Researchers gathered 62 people who had never taken a psychedelic before, gave them 19 milligrams of psilocybin, a common psychedelic found in certain fungi, and scanned their brains. Then, they used AI to analyze the drugged and sober brain scans. What emerged was not exactly chaos.

An uninterrupted trip

Stoliker thinks chaos is not a satisfactory explanation for psychedelics’ effect on the brain. “It never really explained why an individual would have a meaningful experience, why they might have insight, why they might experience clarity, and why these might translate into positive psychological changes,” Stoliker says. To investigate if there are other explanations, he and his colleagues designed a study called PsiConnect.

Read full article

Comments

The Stone Age owes its name to tools that survived to our time. The material early humans worked with most, though, was probably wood because it is so much easier to process. Unfortunately, we know very little about Paleolithic woodwork because wood rots relatively quickly. But at Abric Romaní, a rock shelter in Capellades, west of Barcelona, mineral-rich water coated wooden Neanderthal tools in a limestone-like crust. When wood rotted away, it left behind hollow molds that faithfully reflect its shape.

In a recent Science Advances study, a team of Spanish archaeologists has cataloged 597 wooden remains from Neanderthal living areas dating from 62,000 to 40,000 years ago. They found spears, digging sticks, bark trays, parts of shelters, and a club unlike anything seen before, suggesting Neanderthals were likely much more than just Homo sapiens’ dumber cousins.

Beyond hunting gear

The oldest wooden artifacts we have are mostly weapons. They include spears from a German town called Schöningen, a spear tip from Clacton-on-Sea in England, and the spear found alongside an elephant skeleton in Lehringen, Germany. Most came from waterlogged sediments, where a lack of oxygen slowed decay.

Read full article

Comments