LEIDEN, THE NETHERLANDS—According to a statement released by Leiden University, a groundbreaking ancient DNA study has provided new information about a pivotal transitional period in prehistoric Europe. The research underscored the remarkable genetic stability in the Low Countries and shed new light on the mysterious origins of the so-called Bell Beaker culture. A team of geneticists and archaeologists analyzed the genomes of 112 individuals who lived in the Rhine–Meuse region of the Low Countries—today’s Netherlands, Belgium, and northwestern Germany—between 8500 and 1700 b.c. The data revealed that when Europe’s first farmers arrived from Anatolia around 4,500 years ago, Low Countries...