Marriage between first cousins was encouraged in Ancient Greece

On January 16th, CNN had a article about marriage customs in Bronze Age Greece:

Even more surprising was the discovery that around half of those living on the islands married their cousins, while the proportion on the mainland was about a third.

“It’s not 100%, but not everybody has a cousin,” Stockhammer said.

“People have studied thousands of ancestral genomes and there’s hardly any evidence for societies in the past of cousin-cousin marriage. From a historical perspective this really is outstanding,” he added.

Stockhammer and his colleagues believe such unions were down to economics, to prevent family land from being divided.

He explained: “All of the driving force is to unite the land within the family. If you look at what people were growing, it was grapes and also olives for olive oil, but both grapes and olives might need to be at a certain place for decades.

“If you marry in your family it means that you focus on staying in the same area.”

He said that, by contrast, in other parts of Bronze Age Europe, women often traveled hundreds of miles in order to marry. Resources in those areas would have been more plentiful, he explained.

“In Greece, there’s not much space to grow things and things that you plant need decades to grow,” he said.

“We can completely see the cousin to cousin marriage from the genomic evidence. It’s too many people doing it to say it’s pure chance – but it isn’t 100%. I would say it was quite a strict practice.

“It’s an unwritten rule because everyone has done it.”