Bronze Age man had a grape-sized stone in his urinary tract

A man who lived about 5,300 years ago, in what is now southwestern Russia, had a hard mineral stone inside his body about the size of a grape. Researchers who examined the lump say it formed in his urinary tract, and that a long-lasting infection — not his diet — was the reason it grew.

Found among the bones of his hand

The man was buried in a kurgan cemetery, an old tradition of the steppe in which a large mound of earth is piled over a grave. The site lies in the Stavropol Upland region of southwestern Russia. When archaeologists dug into the mound, they found a catacomb, a chamber cut into the ground, and inside it the skeleton of a man who was in his 40s when he died. A flint arrowhead lay near his pelvis.

The stone was not noticed at the graveside. It turned up later, during laboratory work, in the collection of the man's hand bones. It is brownish, round and bumpy, with several protrusions, and measures about 0.8 inches (2.1 centimetres) across. A small crack in the surface showed a crystal-like structure inside.

What the stone was made of

Researchers studied the object with X-rays and other methods. Its main ingredients were calcium and phosphorus. More telling was the presence of a mineral called whitlockite, a rare calcium salt that is known to occur in kidney, bladder and prostate stones. Hard mineral masses of this kind are called calculi.

Just as important was what the stone did not contain. The team found none of the minerals that form because of what a person eats and drinks, such as calcium oxalate or uric acid. That combination — a phosphate mineral with no diet-related crystals — is a signature of a stone caused by bacteria. The study calls it an "urolith of infectious origin."

What the analysis could not settle was exactly where the stone grew. The researchers say two explanations fit equally well: a kidney stone caused by an infection higher up in the urinary tract, or a stone that formed in the prostate during a long bacterial infection there.

A pain that lasted for years

The study was led by Natalia Berezina, an anthropologist at Lomonosov Moscow State University in Russia. "He lived with a chronic urogenital infection," she said. "It was not a brief episode. His last years were probably marked by considerable and more or less constant pain." Urogenital refers to the parts of the body involved in producing and passing urine, and in reproduction.

The findings were published Sept. 30 in the journal Archaeological and Anthropological Sciences. The paper describes the stone as direct physical evidence of long-term illness: a small, hard record of an infection that never went away, kept in the ground for more than five thousand years.