© TOM BJÖRKLUNDIn Bronze Age Germany, women traveled far from their family of origin to marry; adult sons stayed at home.
Among the most striking of the findings, reported online this week in Science, was an absence: "We were totally missing adult daughters," says team member Alissa Mittnik, a postdoc at Harvard Medical School in Boston. Sons, in contrast, put down roots on their parents' land and kept wealth in the family.
"What shocked me was that you have to give away all your daughters at some moment," says co-author Philipp Stockhammer, an archaeologist at Ludwig Maximilian University in Munich and the Max Planck Institute (MPI) for the Science of Human History in Jena, both in Germany. That poignant glimpse into an ancient culture "could not possibly be recovered ... through any one of these methodologies" alone, says historian Patrick Geary of the Institute for Advanced Study in Princeton, New Jersey, who was not part of the team.
The researchers worked with remains and grave goods excavated more than 20 years ago, when land along the Lech River south of Augsburg was dug up to build a housing development. Radiocarbon dates showed the farmers lived between 4750 years ago and 3300 years ago. Mittnik was working in the lab of Johannes Krause at MPI, and she and her colleagues analyzed DNA across the genomes of 104 people buried on the farmsteads. The team sought clues to the farmers' sex and how they were related to one another. The researchers recalibrated the radiocarbon dates, constraining them to within 200 years in some cases, and identifying four to five generations of ancestors and descendants who lived in that time window.
Some of the early farmers studied were part of the Neolithic Bell Beaker culture, named for the shape of their pots. Later generations of Bronze Age men who retained Bell Beaker DNA were high-ranking, buried with bronze and copper daggers, axes, and chisels. Those men carried a Y chromosome variant that is still common today in Europe. In contrast, low-ranking men without grave goods had different Y chromosomes, showing a different ancestry on their fathers' side, and suggesting that men with Bell Beaker ancestry were richer and had more sons, whose genes persist to the present.
One-third of the women were also buried with great wealth — elaborate copper head-dresses, thick bronze leg rings, and decorated copper pins. They were outsiders, however. Their DNA set them apart from others in the burials, and strontium isotopes in their teeth, which reflect minerals in the water they drank, show they were born and lived until adolescence far from the Lech River. Some of their grave goods — perhaps keepsakes from their early lives — link them to the Únětice culture, known for distinctive metal objects, at least 350 kilometers east in what is now eastern Germany and the Czech Republic.
There was no sign of these women's daughters in the burials, suggesting they, too, were sent away for marriage, in a pattern that persisted for 700 years. The only local women were girls from high-status families who died before ages 15 to 17, and poor, unrelated women without grave goods, probably servants, Mittnik says. Strontium levels from three men, in contrast, showed that although they had left the valley as teens, they returned as adults. That "opens a new window into male life cycles," Geary says.
Bronze Age princely burials have long signaled social inequality. But the organization of these societies remained "rather vague," Stockhammer says. By combining archaeology with DNA data on family ties, the new study sharpened the picture. The data show, for example, that brothers were buried with equally rich grave goods, indicating that all sons, not just the eldest, inherited wealth. Related men kept wealth in the family for four to five generations.
The burials of poor, unrelated people on the same plot suggested inequality thrived within these households. Such complex social structure in these rather modest farmsteads surprised Stockhammer, who says the archaeological record in Europe first shows servants or enslaved people living under the same roof as higher-ranking people 1500 years later, in classical Greece.
Some researchers hope the same barrage of methods will be applied to other sites. Archaeologist Eszter Bánffy, director of the Romano-Germanic Commission of the German Archaeological Institute in Frankfurt, is excited about the results but notes they only provide "narratives for one region and one period. If similar analyses happen widely in time and space," researchers can draw more general conclusions, she says.
"While archaeology has provided the bone structure, archaeogenetics has added the flesh," adds archaeologist Detlef Gronenborn of the Central Museum for Roman and Germanic Art in Mainz, Germany. "The full fascination only emerges when both disciplines are combined."
doi:10.1126/science.aaz8136
Ann Gibbons is a contributing correspondent for Science. Twitter
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