He then was invited to join the faculty of the Department of English at the University of California, Berkeley, where he remained for twenty-six years until taking early retirement.
This research resulted in his book Homo Narrans: The Poetics and Anthropology of Oral Literature (1997), as well as his later study Webspinner: Songs, Stories and Reflections of Duncan Williamson, Scottish Traveller (2022).
His researches into the archaeology and prehistory of early Northwest Europe led to the joint publication Beowulf and Lejre (2007).
This is about the prehistoric Danish site (at the present-day hamlet of Lejre, Zealand) where much of the imagined action of Beowulf is set.
In 2022, Niles was the honorand of a collection of articles, first published as a special issue of the journal Humanities, and subsequently as the book Old English Poetry and Its Legacy.