"Who built Newgrange and the other Boyne Valley passage tombs – and why? It remains one of archaeology’s most intractable questions. In a renewed effort to find some answers, archaeologists are using chemistry to analyse molecules in bone, pottery and artefacts found during early digs at Newgrange and Knowth." - https://www.irishtimes.com/news/science/molecular-archaeology-can-reveal-newgrange-s-secrets-1.4023929