Isithembu (kusuka ku- Late Greek πολυγαμία , Polygamía, "isimo somshado ukuba abangane bomshado abaningi" ) umkhuba eshada amaningi owakwakhe . Lapho owesilisa eshade nabafazi abangaphezu koyedwa ngasikhathi sinye, ososayensi bezokuhlalisana kwabantu bakubiza lokhu ngesithembu.Lapho owesifazane eshade nabesilisa abangaphezu koyedwa ngasikhathi, kubizwa nge- polyandry . Ngokuphambene nesithembu, ukuba nomfazi oyedwa ngumshado oqukethe amaqembu amabili kuphela. Njenge "monogamy", igama elithi "isithembu" livame ukusetshenziswa ngomqondo we- de facto, lisetshenziswe kungakhathalekile ukuthi umbuso uyabubona yini ubudlelwano. Ngo sociobiology futhi kwezilwane, abacwaningi babuye basebenzise isithembu ngomqondo obanzi ukuze kusho noma yiluphi uhlobo amaningi kokuzalela . Emhlabeni jikelele, imiphakathi eyahlukahlukene iyasikhuthaza, iyasamukela noma isenqabele isithembu. Emiphakathini evumela noma isineke isithembu, ezimweni eziningi ifomu elamukelwayo yi-polygyny. Ngokwe- <i id="mwLw">Ethnographic Atlas Codebook</i> (1998), emiphakathini engu-1 231 ephawuliwe, ama-588 ayenesithembu kaningi, ama-453 ayenesithembu ngezikhathi ezithile, abangu-186 babenomfazi oyedwa kanti abane babene-polyandry – yize ucwaningo lwamuva nje lukhombisa ukuthi i-polyandry ingavela ngokujwayelekile kunalokho obekucatshangwa ngaphambili.