Why are there no persisting hybrids of humans with Denisovans, Neanderthals, or anyone else?

Bibliographic Collection: 
APE, CARTA-Inspired Publication
Publication Type: Journal Article
Authors: Ajit Varki
Year of Publication: 2016
Journal: Proceedings of the National Academy of Sciences
Volume: 113
Number: 17
Pagination: E2354-E2354
Publisher: National Acad Sciences
Publication Language: eng
ISBN Number: 0027-8424