Study blames Earth’s magnetic field flip for climate change, extinctions

Image of a large tree

Enlarge / The massive trunk of a kauri tree can remain intact for tens of thousands of years. (credit: W. Bulach / Wikimedia)

The Earth’s magnetic field helps protect life from energetic particles that would otherwise arrive from space. Mars now lacks a strong magnetic field, and the conditions on its surface are considered so damaging to life that any microbes that might inhabit the planet are thought to be safely beneath the surface. On Earth, the magnetic field ensures that life can flourish on the surface.

Except that’s not always true. The Earth’s magnetic field varies, with the poles moving and sometimes swapping places and the field sometimes weakening or effectively vanishing. Yet a look at these events has revealed nothing especially interesting—no obvious connections to extinctions, no major ecological upsets.

A paper published yesterday in Science provides an impressively precise dating for a past magnetic field flip by using rings of trees that have been dead for tens of thousands of years. And it shows the flip was associated with changes in climate. But the paper then goes on to attempt to tie the flip to everything from a minor extinction event to the explosion of cave art by our ancestors. In the end, the work is a mix of solid science, provocative hypothesizing, and unconstrained speculation.

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#biology, #cave-art, #climate-science, #earth-science, #extinctions, #magnetic-field, #science

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This painted pig is the world’s oldest figurative art

Color photo of stylized pig painted in red on a rock wall

Enlarge (credit: Brumm et al. 2021)

A pig painted on the wall of an Indonesian cave is the world’s oldest figurative art—that is, it’s the oldest known drawing of something,

rather than an abstract design or a stencil.

The 45,500-year-old ocher painting depicts a Sulawesi warty pig, which appears to be watching a standoff between two other pigs. If that interpretation is correct, the painting is also a contender for the world’s oldest narrative scene. And it hints at how much the earliest Indonesians observed and recorded about the animals and ecosystems around them. A growing pile of evidence tells us that the first people to reach the islands of Indonesia carried with them a culture of art and visual storytelling, as well as the means to cross the expanses of water between the islands, eventually reaching Australia.

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#ancient-asia, #ancient-people-did-stuff, #archaeology, #cave-art, #cave-paintings, #human-migration, #indonesia, #pleistocene, #rock-art, #science, #sulawesi, #uranium-series-dating

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Rock art in a California cave was a visual guide to hallucinogenic plants

This red pinwheel image (left), which is around 500 years old, may depict the unfurling petals of a datura flower (right).

Enlarge / This red pinwheel image (left), which is around 500 years old, may depict the unfurling petals of a datura flower (right). (credit: Rick Bury and Melissa Dabulamanzi)

At a cave in Southern California, archaeologists recently found centuries-old bundles of hallucinogenic plants tucked into crevices in the low ceiling, near a painting that may depict a flower from the same plant, called datura. The painted images may have been a visual aid to help people understand the rituals they experienced in the cave.

Chew on this

University of Central Lancashire archaeologist David Robinson and his colleagues describe the bundles of leaves and stems tucked into the domed ceiling of California’s Pinwheel Cave. The five-armed pinwheel that gives the cave its name is painted in red nearby, attended by a bizarre-looking figure with antennae, eyes pointed in different directions, and a long body. Archaeologists have dubbed it the Transmorph, perhaps because it wouldn’t answer to anything else they tried. Based on radiocarbon dates of the bundles, people placed them in the room’s nooks and crannies over several centuries, from about 1530 to 1890.

That matches the age of charcoal from nearby chambers in the cave, where people left behind traces of more mundane activities: cooking meat, grinding seeds and nuts, and making stone projectile points. Whatever rituals happened in Pinwheel Cave, they weren’t hidden away or separate from everyday life.

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#ancient-north-america, #ancient-people-did-stuff, #archaeology, #cave-art, #cave-paintings, #chumash, #datura, #drugs, #hallucinogenics, #hallucinogens, #indigenous-communities, #indigenous-north-america, #rock-art, #science

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Paleolithic French didn’t let their dead rest peacefully

Paleolithic French didn’t let their dead rest peacefully

If you died in Europe 35,000 to 25,000 years ago, you’d probably be buried with parts of your body painted with red ochre and bedecked with beads, carved figurines, and other items. Depending on your social standing, you might have just a little body art, or someone might have taken the time to paint your whole body red; you might be buried with just a few beads or with thousands.

But people in at least one part of southwestern France laid their dead to rest in abandoned bear nests in the deepest recesses of a cave—and then returned once the bodies had decomposed to carefully arrange the bones and take away the skulls.

Both a gallery and a tomb

Bears used to make their homes in Grotte de Cussac, a karst cave in southwestern France. They left behind tracks on the floor, claw marks on the walls, and bear-sized depressions in the cave floor where they’d made their hibernation nests. (Pro tip: if you rent to bears, get a very large deposit.) But the bears left “long before any human incursions,” wrote University of Bordeaux archaeologist Sacha Kacki and his colleagues. Traces of human activity in the cave—footprints, torch marks, artwork, and carefully arranged skeletons—lie on top of the bear traces, and not the other way around.

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#ancient-europe, #archaeology, #burials, #cave-art, #paleoanthropology, #paleoarchaeology, #paleolithic-europe, #science, #skeletons, #upper-paleolithic

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Rare miniature rock art found in Australia

Rare miniature rock art found in Australia

(credit: Brady et al. 2020)

Ancient artists used several techniques to paint images on rock. Sometimes they drew by hand, but other times they would place an object like a hand, a leaf, or a boomerang against the wall and spatter it with paint, leaving behind a spray of color surrounding a silhouette of the object. This may sound like a simple way to produce art, but there’s new evidence that it could be a fairly complex process. People in northern Australia seem to have used beeswax to shape miniature stencils to paint on the walls of Yilbilinji Rock Shelter in Limmen National Park.

Welcome to Marra Country

The miniature images are part of a veritable gallery of rock art on the roof and rear walls of Yilbilinji. Over thousands of years, people came here to paint people, animals, objects, tracks, dots, and geometric motifs in striking red, yellow, black, and white. There’s even a European smoking pipe in the mix, which shows that at least some of the paintings must have been created after the colonists arrived.

Out of 355 images painted on the walls, only 59 are stencils—outlines of full-sized hands and forearms surrounded by sprays of white pigment (probably made with local kaolin clay). But 17 of those stencils are too small to have been done the usual way, by spattering an actual object with paint to leave a life-sized outline on the wall. They depict people—sometimes holding boomerangs and shields or wearing headdresses—crabs, echidna, at least two species of turtle, kangaroo pawprints, and geometric shapes.

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#aboriginal-australians, #ancient-people-did-stuff, #anthropology, #archaeology, #australia, #cave-art, #dreamtime, #experimental-archaeology, #indigenous-communities, #rock-art, #science

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