It was once a tidy assumption that the architects of Europe’s impressive megalithic monuments represented a continuous, evolving culture. But then, recent ancient DNA analysis from a 5,000-year-old French megalithic tomb dropped a bombshell: the original population suffered a "dramatic population collapse" and was subsequently replaced by genetically distinct, unrelated newcomers. Apparently, the grand builders didn't just evolve; they vanished, leaving their monumental legacy to a fresh batch of inhabitants.