Fraternal polyandry also accomplishes this, but does so by keeping all the brothers together with just one wife so that there is only one set of heirs per generation.
Some forms of polyandry appear to be associated with a perceived need to retain aristocratic titles or agricultural lands within kin groups, and/or because of the frequent absence, for long periods, of a man from the household.
Of the 1,231 societies listed in the 1980 Ethnographic Atlas, 186 were found to be monogamous; 453 had occasional polygyny; 588 had more frequent polygyny; and 4 had polyandry.
Polyandry is less rare than this figure which listed only those examples found in the Himalayan mountains (28 societies).
More recent studies have found more than 50 other societies practicing polyandry.
Fraternal polyandry was traditionally practiced among Tibetans in Nepal, parts of China and part of northern India, in which two or more brothers are married to the same wife, with the wife having equal "sexual access" to them.
.action_button.action_button:active.action_button:hover.action_button:focus.action_button:hover.action_button:focus .count.action_button:hover .count.action_button:focus .count:before.action_button:hover .count:before.u-margin-left--sm.u-flex.u-flex-auto.u-flex-none.bullet.
Polyandry is contrasted with polygyny, involving one male and two or more females.
If a marriage involves a plural number of "husbands and wives" participants of each gender, then it can be called polyamory, In its broadest use, polyandry refers to sexual relations with multiple males within or without marriage.
In the Indian Himalayas, polyandry may be combined with polygyny to produce a system termed "polygynandry".
The system results in less land fragmentation, a diversification of domestic economic activities, and lower population growth.