Hominids (Neanderthal Parallax Series #1)

Hominids first appeared as a serial in Analog Science Fiction, won the 2003 Hugo Award for Best Novel and was nominated for the John W. Campbell Award the same year; In this polished anthropological SF yarn, Neanderthals have developed a radically different civilization on a parallel Earth, as both sides discover when a Neanderthal physicist, Ponter Boddit, accidentally passes from his universe into a Canadian underground research facility. Fortunately, a team of human scientists, including expert paleoanthropologist Mary Vaughan, promptly identifies and warmly receives Ponter.