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Ancient footprints in Saudi Arabia help researchers track human migrations out of Africa

Ancient footprints in Saudi Arabia help researchers track human migrations out of Africa

Science
Sept. 18 (UPI) -- Paleontologists have discovered a diverse assemblage of 120,000-year-old human and animal footprints in an ancient lake deposit in Saudi Arabia's Nefud Desert, offering new insights into the trajectories of human migrations out of Africa, according to a study published Friday in the journal Science Advances. A mounting body of evidence, compiled and published over the last two decades, has upended early theories that humans migrated out of Africa in one or two giant waves. Advertisement "As more and more fossils are discovered, it seems that humans repeatedly dispersed out of Africa and did so much earlier than previously thought," study co-author Mathew John Stewart told UPI in an email. "Precisely when, how often and under what conditions remain open questions," said S...
Astronomers observe stellar winds from aging stars in unprecedented detail

Astronomers observe stellar winds from aging stars in unprecedented detail

Science
Sept. 17 (UPI) -- Astronomers have captured high resolution images of stellar winds emanating from a diversity of aging stars. The observations, detailed Thursday in the journal Science, suggest the dramatic shapes of planetary nebulae are formed by interactions between stellar winds and nearby planets and stars. Advertisement As dying stars swell and cool, they expel particles and shed mass, producing stellar winds. As the red giants continue to age and evolve, they heat up again, casting off layers of ejected stellar material. Stellar radiation causes these sloughed layers to glow, creating what astronomers call planetary nebulae. Scientists have long struggled to explain the wide variety of shapes and colors that characterize planetary nebulae. "The sun, which will ultimately become a...
Cleanup, waste management aren’t enough to save ecosystems from plastic pollution

Cleanup, waste management aren’t enough to save ecosystems from plastic pollution

Science
Sept. 17 (UPI) -- Even if countries fund massive cleanup efforts and dramatically improve waste management infrastructure, two studies published Thursday in the journal Science suggest it won't be enough to save Earth's ecosystems from plastic pollution. "We simply make too much plastic waste to handle with current waste management infrastructure, and eventually we are going to run out of land to put landfills," ecologist Stephanie Borrelle, research fellow at the University of Toronto, told UPI in an email. Advertisement Plastic pollution is a growing problem for the planet's many ecosystems. From the island reefs and deep sea valleys to polar glaciers and the world's tallest peaks, pieces of plastic, big and small, are showing up everywhere. And it's not just ecosystems. Scientists have...
Plastic pollution: Washed clothing’s synthetic mountain of ‘fluff’

Plastic pollution: Washed clothing’s synthetic mountain of ‘fluff’

Science
When you add it up, the total amount of synthetic microfibres going into the wider environment as we wash our clothes is an astonishing number.US scientists estimate it to be 5.6 million tonnes since we first started wearing those polyester and nylon garments in a big way in the 1950s.Just over half this mass - 2.9 million tonnes - has likely ended up in our rivers and seas.That's the equivalent of seven billion fleece jackets, the researchers say.But while we fret about water pollution, and rightly so, increasingly this synthetic "fluff" issue is one that affects the land.The University of California, Santa Barbara, team which did the calculations found that emission to the terrestrial environm...
Paleontologists find evidence of new mass extinction 233 million years ago

Paleontologists find evidence of new mass extinction 233 million years ago

Science
Sept. 16 (UPI) -- Paleontologists have unearthed evidence of a new mass extinction that occurred during the Late Triassic, some 233 million years ago. The extinction event, which scientists dubbed Carnian Pluvial Episode, was characterized by significant reductions in biodiversity and the loss of 33 percent of marine genera. Advertisement In a new paper, published Wednesday in the journal Science Advances, researchers suggest the episode may have created the ecological space for the emergence of a variety of important modern plant and animal lineages -- including conifers, insects, dinosaurs, crocodiles, lizards, turtles and mammals. Through analysis of both paleontological assemblages and geological evidence, researchers confirmed that biodiversity declines coincided with stark chemical ...