Social animal

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Gorillas and other higher primates are noted as having complex social structures.

Social animals are those animals which interact highly with other animals, usually of their own species (conspecifics), to the point of having a recognizable and distinct society. Many animals are social to the extent that mothers and offspring bond, and males and females interact to mate, but the term "social animal" is usually only applied when there is a level of social organization that goes beyond this, with permanent groups of adults living together, and relationships between individuals that endure from one encounter to another.[1]

Sociality refers to the extent of organization of their social behavior. The levels of sociality include eusocial, presocial (solitary but social), subsocial, and parasocial (including communal, quasisocial, and semisocial).

Animal social behavior and organization is studied in comparative psychology, ethology, sociobiology, behavioral ecology and computer science (artificial intelligence).

Types of sociality

The types of animal sociality include the following.

Eusocial

Main article: Eusociality

Eusociality is the highest level of social organization. It is characterised by:

  • Overlap of adult generations
  • Reproductive division of labour
  • Cooperative care of young

A few species, notably insects of the orders Hymenoptera (ants, bees and wasps) and Isoptera (termites) show an extreme form of sociality, involving highly organized societies, with individual organisms specialized for distinct roles. This form of social behaviour is referred to as eusociality. In termites, the division of labour is divided into reproductives, workers and soldiers. Only two mammal species, the naked mole rat and the Damaraland mole rat, are known to be eusocial. One species of weevil has been described as eusocial

Presocial

Presociality is when animals exhibit more than just sexual interactions with members of the same species, but fall short of qualifying as eusocial. That is, presocial animals can display communal living, cooperative care of young, or primitive reproductive division of labour, but they do not display all of the three essential traits of eusocial animals. Examples include canines that live in packs, numerous insects, especially hymenoptera, humans, many birds and chimpanzees.

Example - Rhesus macaques

Rhesus macaque troops comprise a mixture of 20–200 males and females.[2] Females may outnumber the males by a ratio of 4:1. Males and females both have separate hierarchies. Females have highly stable matrilineal hierarchies in which a female’s rank is dependent on the rank of her mother. In addition, a single group may have multiple matrilineal lines existing in a hierarchy, and a female outranks any unrelated females that rank lower than her mother.[3] Rhesus macaques are unusual in that the youngest females tend to outrank their older sisters.[4] This is likely because young females are more fit and fertile. Mothers seem to prevent the older daughters from forming coalitions against her. The youngest daughter is the most dependent on the mother, and would have nothing to gain from helping her siblings in overthrowing their mother. Since each daughter had a high rank in her early years, rebelling against her mother is discouraged.[5] Juvenile male macaques also exist in matrilineal lines, but once they reach four to five years of age, they are driven out of their natal groups by the dominant male. Thus, adult males gain dominance by age and experience.[6]

Abnormal development: Harry Harlow set up an experiment with rhesus monkeys in 1958. He gave them a choice of a wire mother with a food bottle attached and a similar wire mother wrapped in terry towelling. He found that for 18 hours a day the monkeys cling to the wire mother with terry towelling, so concluded that attachment is not always about food and feeding but that attachment exist when contact comfort is present. The contact comfort is the comfort that is derived from physical closeness with a caregiver. Results from this study showed that social encounters are necessary in order for the young monkeys to develop both mentally and sexually.[7]

Example - Vampire bats

Vampire bats, (Desmodus rotundus), are extremely sociable animals which tend to live in colonies in dark places, such as caves, old wells, hollow trees, and buildings. Vampire bat colony numbers can range in the thousands in roosting sites. The basic social structure of roosting bats is made of harems, which are composed of females and their offspring and a few adult males, known as "resident males" and a separate group of males, known as "non-resident males".[8] In hairy-legged vampire bats, the hierarchical segregation of non-resident males is less strict than in common vampire bats.[8] Nonresident males are accepted into the harems when the ambient temperature lowers. This behavior suggests social thermoregulation.[8]

Resident males mate with the females in their harems, but it is common for outside males to copulate with the females.[9] Female offspring usually remain in their natal groups unless their mothers die or move.[9] Several matrilines can be found in a group, as unrelated females regularly join groups.[9] Male offspring tend to live in their natal groups until they are about two years old, sometimes being forcefully expelled by the resident adult males.[9]

A vampire bat can only survive about two days without a meal of blood, yet they cannot be guaranteed of finding food every night. This poses a problem, so when a bat fails to find food, it will often "beg" another bat for food. The "host" bat may regurgitate a small amount of blood to sustain the other member of the colony. This has been noted by many naturalists as an example of reciprocal altruism in nature.[10] This regurgitation behavior is carried out among bats maintaining a long-term association with one another. Studies have shown that bats will not share their resources equally but will share more often with those that they know they will encounter again, as well as relatives. Therefore, if the same bat is unsuccessful on a following hunt, the bats it is associated with will also share their resources. By reciprocating to one another so that all remain fed, the strength of the vampire bat colony as a whole is steadily increased with no individual bats suffering.

Presocial (Subsocial)

Subsocial is when parents interact with young.

Presocial (Parasocial)

Parasocial is when individuals of the same generation live in a single, cooperative dwelling and interact with each other.

Invertebrates

List of invertebrates showing social behavior

Vertebrates

Features of vertebrate (non-human) societies

Female elephants live in stable groups, along with their offspring.

Social animals may exhibit one of more of these behaviors:

  • cooperative rearing of young by the group
  • overlapping generations living in a permanent, as opposed to seasonal, group
  • cooperative foraging or hunting
  • cooperative defense from predators and competitors
  • social learning (such as a young chimpanzee learning by observation to use a twig to fish for termites)

A chief debate among ethologists studying animal societies is whether non-human primates and other animals can be said to have culture.

List of vertebrates showing social behavior

Human social behavior frequently includes non-human animals (most notably cats, dogs and horses). Animals can provide humans with companionship as pets, or can be kept as livestock, service animals for disabled people, or working animals to perform labor. In many cultures, humans have used animals in religious sacrifice or in staged fights and shows for entertainment such as circuses.

Other animal species may interact cooperatively in symbiotic relationships.

See also

References

  1. ↑ "Social animal". Babylon. Retrieved October 1, 2013. 
  2. ↑ Teas, J., Richie, T., Taylor, H., and C. Southwick. "Population Patterns and Behavioral Ecology of Rhesus Monkeys (Macaca Mulatta) in Nepal." The Macaques: Studies in ecology, behavior, and evolution. Lindenburg, D. San Francisco: Van Nostrand Reinhold Company, 1980
  3. ↑ Judge, P. and F. Waal (1997). "Rhesus monkey behaviour under diverse population densities: coping with long-term crowding." Animal Behaviour 54: 643–662.
  4. ↑ Waal , F. "Codevelopment of dominance relations and affiliative bonds in rhesus monkeys." Juvenile Primates: Life History, Development, and Behavior. Pereira, M., and L. Fairbanks. New York: Oxford Oxford University Press, 1993.
  5. ↑ Hill, D., Okayasu, N. (1996) "Determinants of dominance among female macaques: nepotism, demography and danger." Evolution and Ecology of Macaque Societies. Fa, J. and D. Lindburg. Cambridge: Cambridge University Press
  6. ↑ Southwick, C., Beg, M., and R. Siddiqi (1965) "Rhesus Monkeys in North India." Primate Behavior: Field Studies of monkeys and apes. DeVore, I. San Francisco: Holt, Rinehart and Winston
  7. ↑ Harlow, H.F. and Suomi, S.J. (1971). "Social Recovery by Isolation-Reared Monkeys", Proceedings of the National Academy of Science of the United States of America, 68(7): 1534-1538
  8. ↑ 8.0 8.1 8.2 Delpietro, H.A. and Russo. R.G., (2002). Observations of the common vampire bat (Desmodus rotundus) and the hairy-legged vampire bat (Diphylla ecaudata) in captivity". Mammalian Biology, 67(2): 65–78.
  9. ↑ 9.0 9.1 9.2 9.3 Wilkinson, G.S,. (1985). The social organization of the common vampire bat II: mating system, genetic structure and relatedness. Behavioral Ecology and Sociobiology, 17(2): 123–134
  10. ↑ Dawkins, Richard (2006) The Selfish Gene, Oxford University Press p. 232

Further reading

Edward O. Wilson, The Insect Societies Jae Choe and Bernard J. Crespi (eds) The Evolution of Social Behavior in Insects and Arachnids James T. Costa The Other Insect Societies

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