A genetic analysis of opulent burial mounds in Germany sheds new light on how power passed through family lines

A reconstruction of the central grave in the burial mound of Eberdingen-Hochdorf, located in southwestern Germany Landesmuseum Württemberg / FaberCourtial / Thomas Hoppe

In the Iron Age, many Celtic elites were buried in luxurious graves filled with ceremonial wagons, jewelry, furniture and dining wares. Such burials have made historians wonder: How did these individuals garner such wealth? According to a new study, they got it from their mothers.

Researchers recently conducted genetic testing on 31 skeletons found in seven opulent burial sites in Baden-Württemberg, Germany, all dating to between 616 and 200 B.C.E.

Their analysis found that two men occupying two of the richest graves, located about six miles apart, were related. According to the study, which was published this month in the journal Nature Human Behaviour, the ancient men may have been an uncle and nephew—more specifically, a man and his sister’s son.

“This result shows that political power in this society was most likely inherited through biological succession, comparable to a dynasty,” says study co-author Joscha Gretzinger, a researcher with the Max Planck Institute for Evolutionary Anthropology, in a statement.

The Celts were a group of Central European tribes with similar cultural and religious traditions. First mentioned by ancient Greek writers around the fifth century B.C.E., the tribes thrived during the Iron Age. The rich burial mounds in question were made by “early Celtics,” a group whose societal structures “remain enigmatic,” as the researchers write.

The new genetic testing illuminates an intriguing custom of this mysterious people: “a practice of matrilineal dynastic succession in early Celtic elites,” as the study puts it.

In other words, early Celtics didn’t just inherit power from their families; power appears to have been passed down specifically through female lines. Researchers think the younger deceased man garnered the wealth apparent in his burial through his mother’s side of the family.

As such, “matrilinear avunculate organization”—inheritance via a maternal uncle—is more common in populations that conduct frequent extramarital affairs, which lowers confidence in a child’s true paternity, per the researchers. In such societies, “men are more likely genetically closer related to their sisters’ children than to those of their own wives, ultimately favoring investment in [their] sisters’ children.”

This practice may also explain another finding: Two of the grave occupants were born to parents who were first cousins.

“If a ruler has children on their own but also passes power to their sister’s children, then there might be an incentive to merge the direct and the sister’s lineage, which would then result in first-cousin matings through the female line,” study co-author Stephan Schiffels, a population geneticist at the Max Planck Institute, tells Live Science’s Kristina Killgrove. “But we cannot prove such a scenario from the genetic data.”

Inbreeding and inheritance practices aside, the uncle and nephew also hold another distinction. As study co-author Dirk Krausse, a government archaeologist for Baden-Württemberg, tells Live Science, the two men are among the tallest Iron Age Germans ever recorded: They were both about 5-foot-11. The researchers attribute their stature to the nutritious diets they likely enjoyed as a wealthy, powerful family.

Get the latest stories in your inbox every weekday.