Influence of hashish extract on the social behaviour of encountering male baboons (Papio c. anubis).

The effects of hashish extract (2 mg delta 9-THC/kg)on the social behaviour of encountering male baboons were tested by ethological methods. In the "approaching" male the drug reduced "approach" and the aggressive elements "hit-ground", "brows-back" and "attack" but increased the frequency of "retreat". Social interactions were generally diminished. In the "retreating" male friendly social interactions as "lipsmack" and "touch-back/handle-genitals" were suppressed but the threatening elements "open-mouth" and "tooth-grind" were stimulated. "Retreat" was additionally more frequent. Non-social activities and locomotion were not affected in either of the males. Treating both subjects with hashish resulted in a reduction of "lipsmack", "approach", "fight" and "chase" in the approaching and "lipsmack", "touch-back/handle-genitals", "chase", "retreat" and "flee" in the retreating male. Social activities were generally reduced in both animals. Comparing the behavioural effects of hashish in male baboons to those described in other non-human primates, in rodents but also in man revealed analogous effects in all species. The drug generally impaired social interactions, induced social withdrawal and led to social isolation of the drugged subject.