He spent the following years traveling in Southern and Eastern Africa, conducting research for what was to become his first book on the subject, African Genesis (1961), ultimately an international bestseller.

[3][15]: 1 After graduating from the University of Chicago, under the continuing mentorship of Thornton Wilder, Ardrey wrote a novel, several plays, and many short stories, all of which remained unpublished.

[15]: 53–8  While in Los Angeles he would meet and work with Samuel Goldwyn, Clarence Brown, Pandro Berman, Garson Kanin, Gene Fowler, Lillian Hellman, Sidney Howard, and S.N.

"[15]: 60  He moved with his new wife back to the east coast and set to work, first on a minor project which he would abandon, and then on the play that would become Thunder Rock.

"[15]: 63 (quoted) [17]: 23 In his autobiography, Ardrey gives the following summary of the play: My story was that of a renowned journalist who having experienced the disillusionments of the 1930s had given up all hope of influencing man toward a better world.

"[29] During the summer of 1940 Ardrey discovered, when he read a syndicated column from Britain, that unbeknownst to him Thunder Rock had been having a massively successful run in London.

The play had been so successful that the British Minister of Information, Duff Cooper, arranged to have the Treasury department fund a production at the Globe Theatre in London's West End.

Eminent theater critic Harold Hobson wrote of Thunder Rock: "The theatre ... did a great deal to keep the morale of the British people high.

[15]: 67 [17]: 24–6  It continues to be commonly produced in American university theaters and productions have gone up all around the globe, including in Harare (formerly Salisbury), Zimbabwe, and Nairobi, Kenya.

[15]: 68 In 1946, after a series of talks with RKO, Ardrey and his new agent Harold Norling Swanson negotiated the first-ever independent contract with a major Hollywood studio for him to write the screen adaptation of the A. J. Cronin novel The Green Years.

[15]: 76  The contract stipulated that Ardrey could work at his home in Brentwood – an unprecedented studio concession – and he was not to be bothered until he completed the screenplay in around six weeks.

Jeb was a play about a disabled African American soldier returning to his home in the rural south after having fought in the war in the Pacific.

[35] It received largely positive reviews (famed American theatre critic George Jean Nathan called it the best play on the topic of civil rights) and found small but enthusiastic audiences.

[15]: 95  However, due to factors including high production costs and relatively low revenues, the play had to close after a run of only one week.

[15]: 106  Following the founding of the Committee for the First Amendment, Ardrey flew to Washington, along with Lauren Bacall, Humphrey Bogart, Gene Kelly, Danny Kaye, and John Huston, to defend The Hollywood Ten.

He travelled to Paris, Madrid, Barcelona, the Riviera, Venice, Yugoslavia, where he spent a month living in Belgrade, Greece, Istanbul, and Munich.

Heston, in his autobiography, wrote about his decision to take the role: "It's a good part, presents the challenge of doing a mystic, as well as the English thing.

This led Dart to theorize that in australopithecines, as man's direct ancestors, the use of weapons evolutionarily predated the development of large brains.

In his New York Times obituary, Bayard Webster wrote, "A closer look at his dramas and his behavioral books disclose that he was writing about social conditions in both genres.

The biologist and naturalist E. O. Wilson admired The Hunting Hypothesis, commenting: In his excellent new book Robert Ardrey continues as the lyric poet of human evolution, capturing the Homeric quality of the subject that so many scientists by and large feel but are unable to put into words.

[55][56] Ardrey wrote for popular audiences on topics in paleoanthropology, which encompasses anthropology, ethology, paleontology, zoology and[57] human evolution.

The Observer, for instance, in its review of The Social Contract, wrote that "Robert Ardrey ... leaps across the fences with which scientists nowadays surround their special subjects.

Along with Raymond Dart and Konrad Lorenz, Robert Ardrey became one of the three most famous proponents of the hunting hypothesis and the killer ape theory.

[59] Ardrey postulated that precursors of Australopithecus survived millions of years of drought in the Miocene and Pliocene epochs, as the savannah spread and the forests shrank, by adapting the hunting ways of carnivorous species.

The killer ape theory posits that aggression, a vital factor in hunting prey for food, was a fundamental characteristic which distinguished prehuman ancestors from other primates.

[8] A 1967 review by Patrick Bateson said "The arguments on which he bases his conclusions are shot through with such elementary mistakes, and his definitions are so loose, that he will surely mislead anyone who takes him seriously .

Robert Ardrey has misunderstood two of the basic concepts of the new biology, "aggression" and "territory", and has misapplied them in discussing human society".

[13] A 1972 review by David Pilbeam said Ardrey's ideas were "based upon misinterpretation of ethological studies and a total ignorance of the rich variety of human behavior documented by anthropologists".

[14] A 1976 review said "Ardrey started with an idea that he derived from Raymond Dart and set out to prove it by selecting only the evidence that favored his viewpoint".

[75] A 1984 article said "the hard evidence for Ardrey's killer-ape hypothesis, all from Dart, is slim" and was refuted in the early 1970s by paleontologists, in particular CK Brain and Elisabeth Vrba.