The Greek astronomer Hipparchus, who lived around 120 BCE, usually gets credit for discovering the equinoxes and their relationship to the zodiac constellations. But in a controversial new study, researchers point to ancient cave paintings as proof that people who lived nearly 40,000 years ago already had this advanced knowledge of astronomy. If true, this theory would dramatically change the timeline of humanity’s understanding of the natural world.

First author Martin Sweatman, Ph.D., is confident that his paper can dramatically alter our understanding of the ancient world and modern-day academic principles. In the Athens Journal of History paper, he and co-author Alistair Coombs claim that depictions of animals in well-studied ancient cave paintings in France and Spain prove that Hipparchus was tens of thousands years late to the astronomy game.

“Basically, we have defined a new research area — the evolution of an ancient zodiac,” Sweatman tells Inverse. “It also has implications for the origin of writing, science, mathematics, and astronomy of course. It has implications for the origin and evolution of religion.”

Other scientists are not convinced.

David Pearce, Ph.D., the director of the Rock Art Research Institute at the University of the Witwatersrand, tells Inverse that these claims “look a bit dicey.” More bluntly, Paul Pettitt, Ph.D., a Durham University professor who specializes in Palaeolithic art, tells Inverse that the study is “embarrassingly bad.”

cave art
The Lascaux shaft scene.

Employed as a reader in chemical engineering at the University of Edinburgh, Sweatman’s research nevertheless extends into archeology. In 2017, he co-authored a paper claiming that the Turkish archeological site Göbekli Tepe is a memorial to a mini Ice Age known as the Younger Dryas period. His interest in other sites with ancient animal symbols led to the new paper.

Sweatman and Coombs argue that their conclusions and methodology are practically foolproof:

Essentially, our statistical result is so strong that, unless a significant flaw in our methodology is found, it would be irrational to doubt our hypothesis. It follows that any proposition about these artworks that is inconsistent with our hypothesis can automatically be rejected — it is certainly wrong, since our hypothesis is almost certainly correct.”

The accepted history of the equinoxes and zodiac holds that back in ancient Greece, Hipparchus discovered that equinoxes move along the plane of Earth’s orbit. This movement, which he called the “precession of the equinoxes” (and gives us the four seasons), leads the equator to pass through the center of the sun twice a year, which is when the Sun is directly above the equator.

The sun, completing one circuit each year, appears to move through the constellations of the zodiac, animal-shaped constellations such as Aries the ram and Leo the lion typically credited to the astronomers of ancient Mesopotamia.

Sweatman and Coombs argue that cave-dwelling humans who made art in the Chauvet cave of northern Spain, the Lascaux site in France, and Neolithic sites like Göbekli Tepe, had figured out the equinox and constellations long before Hipparchus and the Babylonians.

“Our work essentially proves the animal symbols used in Paleolithic cave art represent star constellations,” Sweatman says. “We know this, because when we compare the dates of this art, determined by the radiocarbon method, with our predictions based on our zodiacal method, we find an extraordinary level of agreement for all European Paleolithic art.”

They claim that the cave art in Chauvet, Lascaux, and Göbekli Tepe doesn’t just depict any animals — they depict animal-shaped constellations, the same ones Hipparchus spotted in 120 BC. The Lascaux shaft scene, for example, shows four figures of animals and three geometric shapes and dates to about 15,200 BCE. In the paper, Sweatman argues this scene actually shows four animal-shaped constellations corresponding to the solstices and equinoxes — and may also commemorate a comet strike.

The Lion-Man.

In Sweatman’s “zodiacal method,” he and Coombs compared the radiocarbon-derived date of ancient art to the position of the constellations in the sky at the time the cave art was created. To do so, they used a software program called Stellarium, which calculates the positions of stars in earlier epochs. They also applied this method to the Lion-Man of Holenstein-Stadel Cave, a fantastical half-beast half-man that’s considered the world’s oldest sculpture.

“Its radiocarbon date is 37,800 BC with an uncertainty of 680 years at the 95 percent confidence level,” Sweatman says of the Lion-Man. “Our zodiacal method predicts its age is between 38,150 and 39,150 BC, corresponding to Caner [the lion symbol] on the winter solstice. These date ranges overlap, so the Lion-Man is consistent with our theory.”

In turn, their theory goes, the overlap of these dates and the creation of the animal cave art means that ancient humans used zodiac constellations to record dates and understand the passing of time. Sweatman figures that people could have defined dates within an accuracy window of 250 years. If so, that would be an unprecedented level of human sophistication for such an early stage of our evolution.

Regardless of how convinced the researchers are of their claim, one thing is clear: Far more compelling evidence will be necessary before this bold new theory is accepted by the mainstream.