In biology

Biology

Biology is a natural science concerned with the study of life and living organisms, including their structure, function, growth, origin, evolution, distribution, and taxonomy. Biology is a vast subject containing many subdivisions, topics, and disciplines...

, a pair bond is the strong affinity that develops in some species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 between the males and females in a pair, potentially leading to breeding. Pair-bonding is a term coined in the 1940s that is frequently used in sociobiology

Sociobiology

Sociobiology is a field of scientific study which is based on the assumption that social behavior has resulted from evolution and attempts to explain and examine social behavior within that context. Often considered a branch of biology and sociology, it also draws from ethology, anthropology,...

 and evolutionary psychology

Evolutionary psychology

Evolutionary psychology is an approach in the social and natural sciences that examines psychological traits such as memory, perception, and language from a modern evolutionary perspective. It seeks to identify which human psychological traits are evolved adaptations, that is, the functional...

 circles. The term often implies either a lifelong socially monogamous relationship or a stage of mating interaction in socially monogamous species. It is sometimes used in reference to human relationships.

Monogamous vole

Vole

A vole is a small rodent resembling a mouse but with a stouter body, a shorter hairy tail, a slightly rounder head, smaller ears and eyes, and differently formed molars . There are approximately 155 species of voles. They are sometimes known as meadow mice or field mice in North America...

s, such as prairie vole

Prairie Vole

The Prairie Vole is a small vole found in central North America. The vole has long, coarse grayish-brown fur on the upper portion of the body and yellowish fur on the lower portion of the body...

s, have significant differences in the density and distribution of vasopressin

Vasopressin

Arginine vasopressin , also known as vasopressin, argipressin or antidiuretic hormone , is a neurohypophysial hormone found in most mammals, including humans. Vasopressin is a peptide hormone that controls the reabsorption of molecules in the tubules of the kidneys by affecting the tissue's...

 receptors in their brain when compared to polygamous voles. These differences are located in the ventral forebrain and the dopamine

Dopamine

Dopamine is a catecholamine neurotransmitter present in a wide variety of animals, including both vertebrates and invertebrates. In the brain, this substituted phenethylamine functions as a neurotransmitter, activating the five known types of dopamine receptors—D1, D2, D3, D4, and D5—and their...

-mediated reward pathway.

Both vasopressin and dopamine act in this region to coordinate rewarding activities such as mating, and regulate selective affiliation. These species specific differences have shown to correlate with social behaviors, and in monogamous prairie voles are important for facilitation of pair bonding.

Varieties

According to evolutionary psychologists David Barash and Judith Lipton, from their 2001 book The Myth of Monogamy, there are several varieties of pair bonds:

• Short-term pair-bond: a transient mating or associations
• Long-term pair-bond: bonded for a significant portion of the life cycle of that pair
• Lifelong pair-bond: mated for life
• Social pair-bond: attachments for territorial or social reasons, as in cuckold
  Cuckold
  Cuckold is a historically derogatory term for a man who has an unfaithful wife. The word, which has been in recorded use since the 13th century, derives from the cuckoo bird, some varieties of which lay their eggs in other birds' nests...
  
   situations
• Clandestine pair-bond: quick extra-pair copulations
• Dynamic pair-bond: e.g. gibbon
  Gibbon
  Gibbons are apes in the family Hylobatidae . The family is divided into four genera based on their diploid chromosome number: Hylobates , Hoolock , Nomascus , and Symphalangus . The extinct Bunopithecus sericus is a gibbon or gibbon-like ape which, until recently, was thought to be closely related...
  
   mating systems being analogous to "swingers
  Swinging
  Swinging or partner swapping is a non-monogamous behavior, in which both partners in a committed relationship agree, as a couple, for both partners to engage in sexual activities with other couples as a recreational or social activity...
  
  "

Examples

When discussing the social life of the bank swallow, Lipton and Barash state:

For about four days immediately prior to egg-laying, when copulations lead to fertilizations, the male bank swallow is very busy, attentively guarding his female. Before this time, as well as after—that is, when her eggs are not ripe, and again after his genes are safely tucked away inside the shells—he goes seeking extra-pair copulations with the mates of other males…who, of course, are busy with defensive mate-guarding of their own.

In various species, males provide parental care and females mate with multiple males. For example, recent studies show that extra-pair copulation frequently occurs in monogamous birds in which a "social" father provides intensive care for its "social" offspring.

A University of Florida

University of Florida

The University of Florida is an American public land-grant, sea-grant, and space-grant research university located on a campus in Gainesville, Florida. The university traces its historical origins to 1853, and has operated continuously on its present Gainesville campus since September 1906...

 scientist reports that male sand gobies work harder at building nests and taking care of eggs when females are present – the first time such "courtship parental care" has been documented in any species.

See also

• Human bonding
  Human bonding
  Human bonding is the process of development of a close, interpersonal relationship. It most commonly takes place between family members or friends, but can also develop among groups such as sporting teams and whenever people spend time together...
  
  
• Monogamy
  Monogamy
  Monogamy /Gr. μονός+γάμος - one+marriage/ a form of marriage in which an individual has only one spouse at any one time. In current usage monogamy often refers to having one sexual partner irrespective of marriage or reproduction...
  
  
• Affectional bond
  Affectional bond
  In psychology, an affectional bond is a type of attachment behavior one individual has for another individual, typically a caregiver for her or his child, in which the two partners tend to remain in proximity to one another...
  
  
• Animal sexuality
  Animal sexuality
  Animal sexual behaviour takes many different forms, even within the same species. Among animals other than humans, researchers have observed monogamy, promiscuity, sex between species, sexual arousal from objects or places, sex apparently via duress or coercion, copulation with dead animals,...
  
  
• r/K selection theory
  R/K selection theory
  In ecology, r/K selection theory relates to the selection of combinations of traits in an organism that trade off between quantity or quality of offspring...
  
  

External links

• The neurobiology of pair bonding, from Nature
  Nature (journal)
  Nature, first published on 4 November 1869, is ranked the world's most cited interdisciplinary scientific journal by the Science Edition of the 2010 Journal Citation Reports...