Analysis of a cow's tooth, found at the southern entrance to Stonehenge and dating to the monument's early history, between 2995 and 2900 BC, has helped unravel the mysteries of its construction, according to the British Geological Survey (BGS), which is conducting the research.
Specifically, researchers have discovered a link between Stonehenge and two quarries in Wales, UK, which are believed to be the source of the "legendary" Stonehenge bluestones, as archaeologists and geologists predicted in the 2010s and confirmed by studies published in August 2025.
The BGS recalls that in 1924, archaeologists discovered a carefully placed cow jawbone next to the southern entrance to Stonehenge and dated it to the time of the monument's construction.
Now, researchers from BGS, Cardiff University, and University College London (UCL) have used isotopic analysis of the cow's third molar to discover its diet, environment, and movements.
Specifically, they cut the cow's third molar, which records chemical signals from the animal's second year of life, into nine horizontal sections. They were then able to measure the isotopes of carbon, oxygen, strontium, and lead, each of which provides clues about the cow's diet, environment, and movement.
Thus, oxygen isotopes revealed that the tooth captured about six months of growth, from winter to summer, while carbon isotopes showed that the animal's diet changed with the seasons: forest forage in winter and open pasture in summer. Furthermore, strontium isotopes indicated that seasonal food sources came from different geological zones, suggesting that the cow moved seasonally or that winter forage was imported.
Furthermore, lead isotopes revealed peaks in composition from late winter to spring, suggesting an older source of lead than the lead present in the rest of the tooth. Furthermore, the composition suggests that the cow originated in an area with Paleozoic rocks, such as the blue sandstones of Wales, before being moved to Stonehenge.
As the BGS points out, this is the first time scientists have found evidence linking cattle remains from Stonehenge to Wales, reinforcing the theory that cows were used to transport the enormous boulders across the country.
BGS Honorary Research Associate Jane Evans said the study “has revealed unprecedented details of six months in the life of a cow and provided the first evidence of cattle moving from Wales, as well as documenting dietary changes and life events that occurred around 5,000 years ago.”
In addition to this discovery, the researchers concluded that the "unusual" lead signal could not be explained by local contamination or movement alone and could be due to lead stored in the cow's bones being remobilized during the stress of pregnancy, making it likely that the animal was a female.
For Michael Parker Pearson, Professor of British Prehistory at University College London, "this is even more fascinating evidence of Stonehenge's connection to southwest Wales, where its bluestones come from." "It raises the tantalizing possibility that livestock helped transport them," he noted.
