In social anthropology and sociobiology, polyandry (Greek: poly- many, andros- man) refers to a form of polygamous marriage, or other sexual union, in which one individual is married to two or more husbands at the same time. Polygyny, on the other hand, refers to polygamy in which one man is married to two or more wives.
According to inscriptions describing the reforms of the Sumerian king Urukagina of Lagash (ca. 2300 BC), he is said to have abolished the former custom of polyandry in his country, on pain of the woman taking multiple husbands being stoned with rocks upon which her crime is written.
Polyandry in human relationships occurs or has occurred in Tibet, the Canadian Arctic, Zanskar, Nepal, Bhutan, Ladakh, the Nymba, and Sri Lanka, and is known to have been present in some pre-contact Polynesian societies , though probably only among higher caste women . It is also encountered in some regions of Mongolia, among the Mosuo people in China, and in some Sub-Saharan African such as the Maasai people in Kenya and northern Tanzania  and American indigenous communities. Polyandry has been practiced in several cultures in India — in the Jaunsar region in Uttarakhand, among the, Nairs, Theeyas and Toda of South India, and the Nishi of Arunachal Pradesh. The Guanches, the first known inhabitants of the Canary Islands, practiced polyandry until their disappearance. In other societies, there are people who live in de facto polyandrous arrangements that are not recognized by the law. There are no known indigenous communities that currently practice polyandry involving unrelated males.
Differences of interpretation
Polyandry is a controversial subject among anthropologists. For instance, Pennsylvania anthropologist Stephen Beckerman points out that at least 20 tribal societies accept that a child could, and ideally should, have more than one father, referring to it as "partible paternity". On the other hand, in Tibet, which is the best-documented cultural domain within which polyandry is practised, the certain polyandrists themselves testify that the marriage form is difficult to sustain.
In Tibet polyandry has been outlawed, so it is difficult to measure the incidence of polyandry in what may have been the world's most "polyandrous" society.
In other parts of the world, most traditional societies have been drastically altered or destroyed, so the incidence of polyandry in the past may not be accurately known. In India, among Tibetan refugee groups who fled the Chinese takeover of their country, polyandry is seldom encountered.
The Zo'e tribe in the State of Para on the Cuminapanema River, Brazil also practice polyandry.
The Hebrew Bible prohibits polyandry. For a woman to have sexual relations when she is married to another (which would include a situation such as polyandry) would constitute adultery, with the consequences that it would have on her status, as well as of her children from that relationship.
Islam also bans polyandry. In Islam the verse from the Quran that is typically used for a proof in this matter is Surah Nisa’ Chapter 4 verses 22 to 24, which gives the list of women with whom one cannot marry and it is further mentioned in Surah Nisa’ Chapter 4 verse 24. Nikah Ijtimah, a pre-Islamic tradition of polyandry, was forbidden by Islam.
There is at least one reference to polyandry in the ancient Hindu epic, Mahabharata. Draupadi marries the five Pandava brothers. This ancient text remains largely neutral to the concept of polyandry, accepting this as her way of life.
In Mormonism it was practiced by Joseph Smith and other early leaders of the Mormon movement as part of its doctrine of polygamy. Dr. Todd Compton in his celebrated work "In Sacred Loneliness", a depiction of Smith's polygamous marriages, asserts that Polyandry was an integral part of Smith's polygamy rather than an anomaly: “A common misconception concerning Joseph Smith's polyandry is that he participated in only one or two such unusual unions. In fact, fully one-third of his plural wives, eleven of them, were married civilly to other men when he married them. If one superimposes a chronological perspective, one sees that of Smith's first twelve wives, nine were polyandrous. So in this early period polyandry was the norm, not the anomaly." (Todd Compton, In Sacred Loneliness, pp. 15-16)
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. In Tibet the practice is particularly popular among the priestly Skye class but also among poor small farmers who can ill afford to divide their small holdings. As to the latter variety, as some males return to the household, others leave for a long time, so that there is usually one husband present.
Fraternal polyandry (from the Latin frater - brother) is a form of polyandry in which two or more brothers share one wife or more. It is also termed adelphogamy, but this term also has other meanings.
Fraternal polyandry is found in certain areas of Tibet and Nepal, where polyandry is accepted as a social practice. The Toda people of southern India practice fraternal polyandry, but monogamy has become prevalent recently.
Apart from the famous example of fraternal polyandry in the Mahabharata between the five Pandava brothers and Draupadi, there are other instances, both in Hindu history and folklore. In contemporary Hindu society, many social scientists have expressed a fear of critical compulsion of polyandry in the near future.
Fraternal polyandry achieves a similar goal to what primogeniture did in 19th-century England. Primogeniture dictated that the eldest son inherited the family estate, while younger sons had to leave home and seek their own employment. Primogeniture maintained family estates intact over generations by permitting only one heir per generation. 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.
In the field of behavioural ecology polyandry is a type of breeding adaptation in which one female mates with many males. Another similar breeding system to this is polygyny in which one male mates with many females (e.g., lions, deer, some primates and many systems where there is an alpha male).
A common example of this can be found in the Field Cricket Gryllus bimaculatus of the invertebrate order Orthoptera (containing crickets, grasshoppers and groundhoppers). The unusual thing about polyandry in nature in general is that mating is costly: in other words, why mate with more than one male when you could be better spending your time foraging? Females in this species will mate with any male close to them, including siblings. Widely shown in frogs (Agile frogs, Rana dalmatina), polyandry was also documented in polecat (Mustela putorius) and other mustelids. Related to sexual conflict, Thierry Lodé found possible explanations for polyandry include mate competition and inbreeding avoidance.
- It is easier to ensure reproductive success (i.e. it is more likely that the female will have offspring)
- Females may be encouraging sperm competition between males post-copulation
- Multiple sperm lines may confer more variation in traits to female's offspring, this seems to be the case in the honey bee where bees from different sperm lines excel at different roles within a single hive, benefiting the health of the hive as a whole.
- Females may receive food offerings from prospective mates inciting copulation
- Because males can't be sure if they are or aren't their offspring and won't risk destroying their own DNA, mating with multiple males increases the survival of the female's offspring.
Polyandry also occurs in some primates such as marmosets ), mammal groups, the marsupial genus' Antechinus and bandicoots, around 1% of all bird species, such as jacanas, insects such as honeybees, and fish such as pipefish. In effect polyandry will reduce the effective population size of a given closed population.
Polyandry in New World monkeys
Some New World monkeys, for example Goeldi's Marmoset, have been observed living in polyandrous groups. Although groups may contain more than one female, the dominant female suppresses ovulation in subordinates, causing her to be the only one capable of reproduction. A Goeldi's Marmoset female regularly births more than one offspring, and her eggs are separately fertilized by more than one male. Paternal investment is high among Goeldi's Marmosets, and males often carry infants on their backs even if they are not the father of the infant. It has been suggested that multiple male mates were related, and therefore cooperation in caring for each other's young is adaptive; however, researchers tagged and tracked Goeldi's Marmosets over time, and noticed that unrelated males migrated to new groups to cooperate with non relatives as well as with relatives to care for young. It has also been suggested that females select cooperative males, and that the multiple offspring of Goeldi's Marmosets require paternal care for survival.
Current research suggests that polyandry is the dominant social structure in the Callitrichinae subfamily of New World monkeys.
Sociobiology of polyandry
The term has gained some currency in sociobiology, where it refers, analogously, to a mating system in which one female forms more or less permanent bonds to more than one male. It can take two different forms. In one, typified by the Northern Jacana and some other ground-living birds, the female takes on much the same role as the male in a polygynous species, holding a large territory within which several males build nests. Subsequently, the female lays eggs in all the nests, and plays little part in parental care. In the other form, typified by the Galápagos Hawk, a group of two or more males (which may or may not be related) and one female collectively care for a single nest. The latter situation more closely resembles typical human fraternal polyandry.
These two forms reflect different resource situations: polyandry with shared parental care is more likely in very difficult environments, where the efforts of more than two parents are needed to give a reasonable chance of rearing young successfully.
Honeybees are said to be polyandrous because a queen typically mates with multiple males, even though mating is the only interaction that they have (the males die off, while the queen uses stored sperm for eggs she fertilizes).
Polyandry in primates and other mammals is usually correlated with reduced or reverse sexual dimorphism — females larger than males. When males of a species are much larger than females, polygyny is usually practiced. As size difference decreases, or the females are larger than males, a species is more likely to practice monogamy or polyandry. The great apes (gorillas, orangutans, and chimpanzees) are dismorphic and practice polygyny. Male and female gibbons (lesser apes) are similar in size and form monogamous pairs. Human males and females are less dismorphic in body size than other polygynous great apes.
Source : http://en.wikipedia.org/wiki/Polyandry