How might early hominids have defended themselves against large predators and food competitors?

Judging from comparative data on mortality and survival strategies among the higher primates, the early hominids must have used weapons in order to defend themselves effectively against their Natural enemies. They were, however, too small and too weak for throwing big stones or for wielding heavy sticks in the chimpanzee manner. Did they use thorn branches? Experiments in which a bait was covered with a shield of thorn branches showed that wild-living lions are highly afraid of thorns and hardly dare to touch them with their paws. The accompanying behavioural symptoms indicated stress resulting from inhibitions. In the final experiment the bait was protected against wild-living, tame lions by an electrically operated helicopter-like rotor with four blades on which some thorn branches were attached. Every time a lion closely approached the bait the rotor was operated for a split-second, causing the nearby lions to jump wildly away. When finally a lion was struck on the nose all three lions present walked away and did not return until I had myself left. This excessive fear of suddenly moving thorn branches could perhaps indicate that the responses of carnivores which were originally adapted to porcupines, facilitated the use of thorn branches as defensive weapons among the incipient hominids. The evolution of this behaviour may have started among dryopithecines living in dry woodlands and would have promoted the emergence of regular bipedal gait.