produced by Judy Kinberg ; directed by Merrill Brockway ; written by Holly Brubach ; a production of Thirteen/WNET New York in association with Société Radio-Canada & British Broadcasting Corporation
a BBC/WGBH Boston/ProSieben co-production [in association with France 3 ; produced and directed by John Hayes Fisher ; produced for Nova by Gary Glassman ; senior executive producer, Paula S. Apsell
a production of Média Vérité and Café Productions in association with BBC, History Television Inc., Public Broadcasting Service, U5 Filmproducktion GmbH ; written by Malcom Clarke ; produced by Malcolm Clarke and Karl-Eberhard Schaeffer ; directed by Malcolm Clarke and Stuart Sender
narrated by Paul Christie ; directed & produced by Tom Mustill ; AGB Films with Gripping Films for Thirteen Productions LLC and BBC in association with WNET
narrated by F. Murray Abraham ; a production of Brian Leith Productions, Thirteen/WNET New York and BBC ; producer, Brian Leith ; director, Steve Gooder
narrated by Daniel Stern ; written and directed by Steve Gooder ; an OSF Wales production for BBC and Thirteen Productions LLC in association with WNET
produced and directed by Paul Thompson ; a BBC Studios Natural History Unit production for PBS ; a BBC Studios production for PBS, BBC and Tencent Penguin Pictures ; a BBC partnership with Open University