Headlines scream about it. The 67,000-year-old hand stencil. The 51,000-year-old warty pig. It’s supposed to be a race to the past, pushing boundaries.
But is the clock actually ticking right?
Georges Sauvet, a French prehistorian, says no. He’s looking at the numbers and seeing flaws. Specifically in the uranium-th dating method. He calls it a rush to antiquity that skips necessary checks.
“The validity of some of these dates has come into question,”
Sauvet isn’t alone. But he’s loud. He argues that researchers are ignoring caution for prestige. If you publish that a cave painting is ancient, you get grants. You get fame. But do you get truth?
The Problem With Closed Systems
Uranium-thorium dating works like this.
Water drips on limestone. Calcite forms. Uranium gets trapped. It decays into thorium over time. Simple chemistry.
Uranium-234 drops protons. It becomes Thorium-230. It takes 245,620 years for half of it to change. You measure the ratio. You get an age.
Except the system has to be closed.
No leaks. No extra water sneaking in or out.
In the real world, caves leak. Rainwater percolates. Groundwater moves. It leaches uranium away.
When uranium leaves the mix, the math breaks.
The ratio suggests the deposit is older than it really is. The art looks ancient because the minerals above it are lying.
Spanish Cave Disputes
Sauvet pointed a finger at a 2018 study. Dirk Hoffmann and team said Neanderthals painted Spanish caves 65,00 years ago.
Neanderthals. Not Homo sapiens.
The claim implies complex art by our extinct cousins.
Sauvet and forty-two others responded. They highlighted the closed system problem. Without proof that no uranium was lost, those dates are just guesses dressed up as science.
Did Neanderthals have art?
Some think so. Others say we just don’t have the proof yet.
If the Spanish dates are wrong, we lose that potential proof. We go back to square one.
Cases Of Open Systems
Take Nerja Cave. Southern Spain.
A U-Th test said a layer was 119.000 years old.
A carbon date on charcoal in the same drawing said 19.000.
Another carbon date on the calcite said 14.000.
That’s a discrepancy of almost a hundred thousand years.
Look at Leang Balangajia in Indonesia.
The outer calcite layer is the youngest. It formed last. Right?
U-Th said it was 37.300 years old.
The layer underneath was only 29.500.
The skin is older than the meat. Impossible in a closed system. It means uranium leaked. It means the dates are skewed.
“Dating of rock art is particularly challenging.”
Adelphine Bonneau, a chemistry professor, agrees in principle. She says U-Th can lead to overestimation if not handled carefully.
But she thinks Sauvet throws the baby out with the bathwater.
Laser Ablation Fixes This
Defenders of the method don’t deny the errors. They just have a fix.
Maxime Aubert, who worked on the Indonesian pig and hand stencils, uses laser ablation.
His team shoots lasers at tiny sections of the calcite.
They map the isotope ratios across the whole layer.
They spot the messy zones. The open system zones where water got in. They ignore them.
Only the clean, stable zones get counted for the age.
Aubert argues that dismissing U-Th entirely because some samples leak is wrong. It’s like throwing away thermometers because one was left in the sun.
We have better ways now. We can see the contamination.
Hoffmann didn’t have this tech in 2018.
Bonneau says he didn’t publish the raw isotope maps. Without them, you can’t verify his work. You’re just trusting his word.
Science requires transparency.
So who’s right?
Sauvet says cross-date everything. Never trust one method alone.
Aubert says modern tech fixes the leak problem. The oldest dates stand.
We might never know if those hand stencils are truly 67.800 years old.
Maybe the paint is old. Maybe the crust is a liar.
Or maybe both.
What do you trust more. The headline. Or the footnote?
