wikipedia discovery: bonobos

Sexual intercourse plays a major role in Bonobo society, being used as a greeting, a means of conflict resolution and post-conflict reconciliation, and as favors traded by the females in exchange for food. Bonobos are the only non-human apes to have been observed engaging in all of the following sexual activities: face-to-face genital sex (most frequently female-female, then male-female and male-male), tongue kissing, and oral sex.[2] In scientific literature, the female-female sex is often referred to as GG rubbing or genital-genital rubbing, while male-male sex is sometimes referred to as penis fencing [citation needed].

Sexual activity happens within the immediate family as well as outside it, and often involves adults and children, even infants.[7] Bonobos do not form permanent relationships with individual partners. They also do not seem to discriminate in their sexual behavior by gender or age, with the possible exception of sexual intercourse between mothers and their adult sons; some observers believe these pairings are taboo. When Bonobos come upon a new food source or feeding ground, the increased excitement will usually lead to communal sexual activity, presumably decreasing tension and allowing for peaceful feeding.[8]

Bonobo males frequently engage in various forms of male-male genital sex (frot).[9] [3][4] One form has two males hang from a tree limb face-to-face while "penis fencing". Frot may also occur where two males rub their penises together while in missionary position. A special form of frot called "rump rubbing" occurs to express reconciliation between two males after a conflict, where they stand back-to-back and rub their scrotal sacks together.

Bonobo females also engage in female-female genital sex (tribadism) to socially bond with each other, thus forming a female nucleus of Bonobo society. The bonding between females allows them to dominate Bonobo society - although male Bonobos are individually stronger they cannot stand alone against a united group of females. Adolescent females often leave their troop of birth to join another troop. Sexual bonding with other females establishes the new females as members of the group. This troop migration mixes the Bonobo gene pools.

Bonobo reproductive rates are not any higher than that of the Common Chimpanzee. Female Bonobos carry and nurse their young for five years and can give birth every five to six years. Compared to Common Chimpanzees, Bonobo females resume the genital swelling cycle much sooner after giving birth, allowing them to rejoin the sexual activities of their society. Also, Bonobo females who are either sterile or too young to reproduce engage in sexual activity.