From the time of antiquity field biologists have observed that some organisms tend to exhibit strategies that favor the reproductive success of their relatives, even at a cost to their own survival and/or reproduction. The classic example is a eusocial insect colony, with sterile females acting as workers to assist their mother in the production of additional offspring. Eusociality ( Greek eu: "good" + "social" is a term used for the highest level of social organization in a hierarchical classification Many evolutionary biologists explain this by the theory of kin selection.

The earliest expressions of the basic concepts were by R.A. Fisher in 1930^[1], JBS Haldane in 1955^[2], but it was W. D. Hamilton who truly formalized the concept, in works published in 1963^[3]and - most importantly - in 1964^[4], while the actual term "kin selection" may first have been coined by John Maynard Smith (1964)^[5] when he wrote "These processes I will call kin selection and group selection respectively. Sir Ronald Aylmer Fisher, FRS ( 17 February 1890 – 29 July 1962) was an English Statistician, Evolutionary John Burdon Sanderson Haldane FRS ( 5 November 1892 &ndash 1 December 1964) known as Jack (but who used 'J William Donald Hamilton, FRS ( 1 August 1936 &mdash 7 March 2000) was a British Evolutionary biologist Maynard Smith redirects here -- for other uses see Maynard Smith (disambiguation Professor John Maynard Smith, F In Evolutionary biology, group selection refers to the idea that Alleles can become fixed or spread in a population because of the benefits they bestow on groups regardless Kin selection has been discussed by Haldane and by Hamilton. . . . By kin selection I mean the evolution of characteristics which favour the survival of close relatives of the affected individual, by processes which do not require any discontinuities in the population breeding structure. "

Kin selection refers to changes in gene frequency across generations that are driven at least in part by interactions between related individuals, and this forms much of the conceptual basis of the theory of social evolution. History See also History of genetics The existence of genes was first suggested by Gregor Mendel (1822-1884 who in the 1860s studied inheritance Social Evolution is the title of an essay by Benjamin Kidd, which became available as a book published by Macmillan and co London in 1894 Indeed, some cases of evolution by natural selection can only be understood by considering how biological relatives influence one another's fitness. eVolution is the third Album by eLDee, it was due to be released in 2008 Natural selection is the process by which favorable Heritable traits become more common in successive Generations of a Population of Fitness (often denoted w in Population genetics models is a central concept in evolutionary theory. Under natural selection, a gene encoding a trait that enhances the fitness of each individual carrying it should increase in frequency within the population; and conversely, a gene that lowers the individual fitness of its carriers should be eliminated. Natural selection is the process by which favorable Heritable traits become more common in successive Generations of a Population of A trait is a distinct phenotypic character of an organism that may be inherited environmentally determined or somewhere in between In Biology a population is the collection of inter-breeding organisms of a particular Species; in Sociology However, a gene that prompts behaviour which enhances the fitness of relatives but lowers that of the individual displaying the behavior, may nonetheless increase in frequency, because relatives often carry the same gene; this is the fundamental principle behind the theory of kin selection. According to the theory, the enhanced fitness of relatives can at times more than compensate for the fitness loss incurred by the individuals displaying the behaviour. As such, this is a special case of a more general model, called "inclusive fitness" (in that inclusive fitness refers simply to gene copies in other individuals, without requiring that they be kin). There are a few definitions of Inclusive fitness (IF but one (that according to Oli 2003 is not consistent with W

Contents 1 Hamilton's rule 2 Mechanisms 3 Kin Selection in Evolutionary Psychology 4 Examples 5 See also 6 References

Hamilton's rule

Formally, such genes should increase in frequency when

where

r = the genetic relatedness of the recipient to the actor, often defined as the probability that a gene picked randomly from each at the same locus is identical by descent. In the fields of Genetics and Evolutionary computation, a locus (plural loci) is a fixed position on a Chromosome such as the position of a

B = the additional reproductive benefit gained by the recipient of the altruistic act,

C = the reproductive cost to the individual of performing the act.

This inequality is known as Hamilton's rule after W. D. Hamilton who published, in 1964, the first formal quantitative treatment of kin selection to deal with the evolution of apparently altruistic acts. William Donald Hamilton, FRS ( 1 August 1936 &mdash 7 March 2000) was a British Evolutionary biologist eVolution is the third Album by eLDee, it was due to be released in 2008 Altruistic acts are those that benefit the recipient but harm the actor. The phrase Kin selection, however, was coined by John Maynard Smith. Maynard Smith redirects here -- for other uses see Maynard Smith (disambiguation Professor John Maynard Smith, F

Originally, the definition for relatedness (r) in Hamilton's rule was explicitly given as Sewall Wright's coefficient of relationship: the probability that at a random locus, the alleles there will be identical by descent (Hamilton 1963, American Naturalist, p. In Population genetics, Sewall Wright 's coefficient of relationship or coefficient of relatedness or relatedness or r is Sewall Green Wright ( December 21, 1889 – March 3, 1988) was an American Geneticist In Population genetics, Sewall Wright 's coefficient of relationship or coefficient of relatedness or relatedness or r is Probability is the likelihood or chance that something is the case or will happen In the fields of Genetics and Evolutionary computation, a locus (plural loci) is a fixed position on a Chromosome such as the position of a An allele (ˈæliːl (UK /əˈliːl/ (US (from the Greek αλληλος allelos, meaning each other) is one member of a pair or series of different forms Alleles have identity by type (IBT if they have the same phenotypic effect. 355). Subsequent authors, including Hamilton, sometimes reformulate this with a regression, which, unlike probabilities, can be negative, and so it is possible for individuals to be negatively related, which simply means that two individuals can be less genetically alike than two random ones on average (Hamilton 1970, Nature & Grafen 1985 Oxford Surveys in Evolutionary Biology). In statistics regression analysis is a collective name for techniques for the modeling and analysis of numerical data consisting of values of a Dependent variable (response This has been invoked to explain the evolution of spiteful behaviours. This page is about spite in the context of Fair division, a branch of theoretical Economics. Spiteful behavior defines an act (or acts) that results in harm, or loss of fitness, to both the actor and the recipient.

In the 1930s J.B.S. Haldane had full grasp of the basic quantities and considerations that play a role in kin selection. John Burdon Sanderson Haldane FRS ( 5 November 1892 &ndash 1 December 1964) known as Jack (but who used 'J He famously said that, "I would lay down my life for two brothers or eight cousins". cousin in Kinship terminology is a relative with whom one shares a common Ancestor, but in modern usage the term is rarely used when referring to a ^[6] Kin altruism is the term for altruistic behaviour whose evolution is supposed to have been driven by kin selection.

Haldane's remark alluded to the fact that if an individual loses its life to save two siblings, four nephews, or eight cousins, it is a "fair deal" in evolutionary terms, as siblings are on average 50% identical by descent, nephews 25%, and cousins 12. 5% (in a diploid population that is randomly mating and previously outbred). "Haplo" redirects here For the fictional character see The Death Gate Cycle. Inbreeding is breeding between close Relatives whether plant or animal But Haldane also joked that he would truly die only to save more than one identical set of twins or more than two full siblings.

Mechanisms

An altruistic case is one where the instigating individual suffers a fitness loss while the receiving individual benefits by a fitness gain. The sacrifice of one individual to help another is an example of altruism.

Hamilton (1964) outlined two ways in which kin selection altruism could be favoured. William Donald Hamilton, FRS ( 1 August 1936 &mdash 7 March 2000) was a British Evolutionary biologist Altruism is selfless concern for the welfare of others It is a traditional Virtue in many cultures and central to many religious traditions

Firstly, if individuals have the capacity to recognize kin (kin recognition) and to adjust their behaviour on the basis of kinship (kin discrimination), then the average relatedness of the recipients of altruism could be high enough for this to be favoured. Kin recognition refers to animals' capabilities to distinguish between close genetic kin and non-kin Because of the facultative nature of this mechanism, it is generally regarded that kin recognition and discrimination are unimportant except among 'higher' forms of life (although there is some evidence for this mechanism among protozoa). Protozoa (in Greek πρῶτον proton "first" and ζῷα zoia "animals" are unicellular Eukaryotes (singular A special case of the kin recognition/discrimination mechanism is the hypothetical 'green beard', where a gene for social behaviour also causes a distinctive phenotype that can be recognised by other carriers of the gene. The Selfish gene theory postulates that Natural selection will increase the frequency of those genes whose phenotypic effects ensure their successful replication Hamilton's discussion of greenbeard altruism serves as an illustration that relatedness is a matter of genetic similarity and that this similarity is not necessarily caused by genealogical closeness (kinship).

Secondly, even indiscriminate altruism may be favoured in so-called viscous populations, i. e. those characterized by low rates or short ranges of dispersal. Here, social partners are typically genealogically-close kin, and so altruism may be able to flourish even in the absence of kin recognition and kin discrimination faculties. This suggests a rather general explanation for altruism. Directional selection will always favor those with higher rates of fecundity within a certain population. Social individuals can often ensure the survival their own kin by participating in, and following the rules of a group.

It should be noted that these mechanisms explain a relatively high r between interacting individuals. Absolute genetic similarity is not a measure of r; rather, r shows the “excess” relatedness between an actor and a recipient compared with the relatedness between an actor and a random member of the population. Thus, in a clonal population with 100% genetic similarity, r = 0 (as strange as that may sound). This is because there can be no correlation between genetic similarity and interaction strengths if genetic similarity is constant. This is why it has often been observed that altruism cannot be maintained in a population of randomly interacting individuals (see ^[7] and references therein). In such a population, the correlation between genetic similarity and interaction strength is necessarily absent, thus r = 0 and rB < C for any C > 0. This is why mechanisms such as spatial structure and kin recognition are so important for the long-term stability of altruistic traits, and why measures such as "population-wide average r" are meaningless in the absence of such mechanisms.

Kin Selection in Evolutionary Psychology

Evolutionary psychologists have attempted to explain prosocial behavior through kin selection by stating that “behaviors that help a genetic relative are favored by natural selection. Evolutionary psychology ( EP) attempts to explain mental and psychological traits ��such as Memory, Perception, ” Human beings have developed a tendency over time to frame and interpret their actions as an avenue to the survival of their genetic material, making kin selection not a completely altruistic form of prosocial behavior and is perhaps better described as a component of social exchange theory. This theory does not necessarily imply that people “compute” genetic benefit when helping others, but there is an indication that those who behave in such a way are more likely to pass on their genes to future generations. ^[8]

Examples

Eusociality (true sociality) is used to describe social systems with three characteristics: one is an overlap in generations between parents and their offspring, two is cooperative brood care, and the third characteristics is specialized castes of nonreproductive individuals. Eusociality ( Greek eu: "good" + "social" is a term used for the highest level of social organization in a hierarchical classification ^[9]Social insects are an excellent example of organisms that display presumed kin selected traits. Eusociality ( Greek eu: "good" + "social" is a term used for the highest level of social organization in a hierarchical classification The workers of some species are sterile, a trait that would not occur if individual selection was the only process at work. The relatedness coefficient r is abnormally high between the worker sisters in a colony of Hymenoptera due to haplodiploidy, and Hamilton's rule is presumed to be satisfied because the benefits in fitness for the workers are believed to exceed the costs in terms of lost reproductive opportunity, though this has never been demonstrated empirically. The haplodiploid sex-determination system determines the sex of the offspring of many Hymenopterans ( Bees Ants and Wasps, and coleopterans ( Fitness (often denoted w in Population genetics models is a central concept in evolutionary theory. There are competing hypotheses, as well, which may also explain the evolution of social behavior in such organisms (see Eusociality). Eusociality ( Greek eu: "good" + "social" is a term used for the highest level of social organization in a hierarchical classification

Alarm calls in ground squirrels are another example. While they may alert others of the same species to danger, they draw attention to the caller and expose it to increased risk of predation. Paul Sherman, of Cornell University, studied the alarm calls of ground squirrels. He observed that they occurred most frequently when the caller had relatives nearby. ^[10]In a similar study, John Hoogland was able to follow individual males through different stages of life. He found that the male prairie dogs modified their rate of calling when closer to kin. These behaviors show that self-sacrifice is directed towards close relatives and that there is an indirect fitness gain. ^[11]

Alan Krakauer of University of California, Berkeley has studied kin selection in the courtship behavior of wild turkeys. The University of California Berkeley (also referred to as Cal, Berkeley and UC Berkeley) is a major research university located in Berkeley Like a teenager helping her older sister prepare for prom night, a subordinate turkey may help his dominant brother put on an impressive team display that is only of direct benefit to the dominant member. ^[12]

Recent studies provide evidence that even certain plants can recognize and respond to kinship ties. Using sea rocket for her experiments, Susan Dudley at McMaster University in Canada compared the growth patterns of unrelated plants sharing a pot to plants from the same clone. Cakile ( Cá-ki-le) is a Genus within the Flowering plant family Brassicaceae. McMaster redirects here for others see McMaster (disambiguation. Country to "Dominion of Canada" or "Canadian Federation" or anything else please read the Talk Page She found that unrelated plants competed for soil nutrients by aggressive root growth. This did not occur with sibling plants. ^[13]

See also

• Altruism
• Group selection
• Inclusive fitness
• The Selfish Gene

References

• Hamilton, W. D. (1964). The genetical evolution of social behaviour I and II. — Journal of Theoretical Biology 7: 1-16 and 17-52. pubmed I pubmed II
• Lucas, J. R. , Creel, S. R. & Waser, P. M. (1996) How to measure inclusive fitness, revisited, Animal Behaviour, 51, 225-228.
• Madsen, E. A. , Tunney, R. , Fieldman, G. , Plotkin, H. C. , Dunbar, R.I.M., Richards, J. Robin Ian MacDonald Dunbar (born June 28, 1947, Liverpool) is a British anthropologist and Evolutionary biologist specialising M. , & McFarland, D. (2007) Kinship and altruism: A cross-cultural experimental study. British Journal of Psychology, 98, 2 [1]
• Queller, D. C. & Strassman, J. E. (2002) Quick Guide: Kin Selection. Current Biology,12,R832. [2]
• West, S. A. , Gardner, A. & Griffin, A. S. (2006) Quick Guide: Altruism. Current Biology,16,R482-R483. [3]

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