Dr. Cassidy said that they also found DNA in other remains that indicated relatives of the man who was a child of royal incest were placed in other significant tombs. “This man seemed to form a distinct genetic cluster with other individuals from passage tombs across the island,” she said.
She said “we also found a few direct kinship links,” ancient genomes of individuals who were distant cousins. That contributed to the idea that there was an elite who directed the building of the mounds. In that context, it made sense that the incest was intentional. That’s not something that can be proved, of course, but other societies have encouraged brother/sister incest, and not only the Egyptians. Brothers married sisters in ancient Hawaii, and in Peru among the Incas.
“The few examples where it is socially accepted,” she said, are “extremely stratified societies with an elite class who are able to break rules.”
Dr. Reich said that the research had implications beyond the specific findings. He said it marked a new direction in ancient DNA studies, moving beyond discoveries of broad patterns of prehistoric human migration. Now, genetic data may help delineate social structures of specific communities, like that in Ireland, so lost in deep time that they have been almost impossible to decipher.
Dr. Reich said he had reservations about one of the paper’s conclusions. The researchers reported that members of the elite, those found in the most elaborate tombs, were closer to one another genetically than they were to people found in other, simpler burials. But, Dr. Reich said, the simpler burials and the higher status burials were separated by hundreds of years, so the comparison wasn’t contemporaneous. Perhaps the genetic makeup of the society, which was small in number, changed over a few centuries. Dr. Bradley acknowledged that this was an alternative explanation.
The final piece of the puzzle that the researchers reported was neither archaeological nor genetic, but folkloric. An account of Irish place names written around 1100, the authors write, tells a tale of a King Bressal, who slept with his sister. The result was that Dowth, the burial mound next to Newgrange, was called Fertae Chuile, or the Mound of Sin.