There are two principal clans or moieties (halves) in Matses society, that of the Jaguar Clan and that of the Worm Clan. These two kinship groups are based on descent and a member of the tribe is either “jaguar-kind” or “worm-kind” depending upon their father’s clan (i.e. patrilineal). The Matses believe that if a member of the jaguar clan even glances at their corn crop, insect larvae (“worms”) will attack the crop and cause it to die. Therefore according to Matses beliefs, only members of the Worm Clan can tend corn in their gardens. These two principal clans are intricately integrated into Matses society and religion, determining an individual’s activities and lifestyle.  Matses society is not exogamous.  However, the preference for marriages between cross-cousins often facilitates marriages between different clans.