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Sociality is the degree to which individuals in an animal population tend to associate in social groups and form cooperative societies. Sociality is a survival response to evolutionary pressures. For example, when a mother wasp stays near her larvae in the nest, parasites are less likely to eat the larvae. Biologists suspect that pressures from parasites and other predators selected this behavior in wasps of the family Vespidae. This wasp behaviour evidences the most fundamental characteristic of animal sociality: parental investment. Parental investment is any expenditure of resources (time, energy, social capital) to benefit one offspring. Parental investment detracts from a parent's capacity to invest in future reproduction and aid to kin (including other offspring). An animal that cares for its young but shows no other sociality traits is said to be ''subsocial''. An animal that exhibits a high degree of sociality is called a ''social animal''. The highest degree of sociality recognized by sociobiologists is ''eusociality''. A eusocial taxon is one that exhibits overlapping adult generations, reproductive division of labor, cooperative care of young, and—in the most refined cases—a biological caste system. Solitary animals, such as the jaguar, don't associate except for courtship and mating. If an animal taxon shows a degree of sociality beyond courtship and mating, but lacks any of the characteristics of eusociality, it is said to be ''presocial''. Presociality is much more common than eusociality among species. Per E.O. Wilson, however, it should be noted the total biomass and impact of eusocial species, including ants, wasps, and Homo sapiens sapiens, "which can be loosely characterized as eusocial," is vastly disproportionate to the quantity of species exhibiting it. == Presociality == Entomologist Charles D. Michener published a classification system for presociality in 1969, building on the earlier work of Suzanne Batra (who coined the words ''eusocial'' and ''quasisocial'' in 1966). Michener used these terms in his study of bees, but also saw a need for additional classifications: ''subsocial'', ''communal'', and ''semisocial''. In his use of these words, he did not generalize beyond insects. E. O. Wilson later refined Batra's definition of ''quasisocial''. An example of a species that exhibits presociality is the wasp species ''Philanthus gibbosus''. ''P. gibbosus'' exhibits presociality in that it lives communally only for a very short amount of time while establishing a new burrow and at other certain phases of the nesting cycle. Apart from those specific points in the nesting cycle, ''P. gibbosus'' has been observed to live completely solitarily. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Sociality」の詳細全文を読む スポンサード リンク
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