Kin selection

[1] Charles Darwin discussed the concept of kin selection in his 1859 book, On the Origin of Species, where he reflected on the puzzle of sterile social insects, such as honey bees, which leave reproduction to their mothers, arguing that a selection benefit to related organisms (the same "stock") would allow the evolution of a trait that confers the benefit but destroys an individual at the same time.

In this case, nurture kinship, the interaction between related individuals, simply as a result of living in each other's proximity, is sufficient for kin selection, given reasonable assumptions about population dispersal rates.

In On the Origin of Species, he wrote about the conundrum represented by altruistic sterile social insects that:[4] This difficulty, though appearing insuperable, is lessened, or, as I believe, disappears, when it is remembered that selection may be applied to the family, as well as to the individual, and may thus gain the desired end.

Haldane grasped the basic quantities in kin selection, famously writing "I would lay down my life for two brothers or eight cousins".

… It is clear that genes making for conduct of this kind would only have a chance of spreading in rather small populations when most of the children were fairly near relatives of the man who risked his life.W.

Inclusive fitness theory is still generally accepted however, as demonstrated by the publication of a rebuttal to Wilson's claims in Nature from over a hundred researchers.

[2][3] The relatedness parameter (r) in Hamilton's rule was introduced in 1922 by Sewall Wright as a coefficient of relationship that gives the probability that at a random locus, the alleles there will be identical by descent.

It may be, for instance, that in respect of a certain social action performed towards neighbours indiscriminately, an individual is only just breaking even in terms of inclusive fitness.

In fact, the individual may not need to perform any discrimination so sophisticated as we suggest here; a difference in the generosity of his behaviour according to whether the situations evoking it were encountered near to, or far from, his own home might occasion an advantage of a similar kind.

Due to conflicting genetic similarity in the rest of the genome, there should be selection pressure for green-beard altruistic sacrifices to be suppressed, making common ancestry the most likely form of inclusive fitness.

[2] Hamilton later modified his thinking to suggest that an innate ability to recognise actual genetic relatedness was unlikely to be the dominant mediating mechanism for kin altruism:[31] But once again, we do not expect anything describable as an innate kin recognition adaptation, used for social behaviour other than mating, for the reasons already given in the hypothetical case of the trees.Hamilton's later clarifications often go unnoticed.

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.

[41] In one experiment, the longer participants (from both the UK and the South African Zulus) held a painful skiing position, the more money or food was presented to a given relative.

The results showed that participants held the position for longer intervals the greater the degree of relatedness between themselves and those receiving the reward.

The relatedness of the individual and the potential inclusive fitness benefit needed to outweigh the energy cost of transporting the food over distance.

For individuals without their own offspring, the inclusive fitness benefits of providing care to closely related children might outweigh the time and energy costs of childcare.

[45] Family investment in offspring among black South African households also appears consistent with an inclusive fitness model.

[46] Observation of the Dolgan hunter-gatherers of northern Russia suggested that there are larger and more frequent asymmetrical transfers of food to kin.

[47] Violence in families is more likely when step-parents are present, and that "genetic relationship is associated with a softening of conflict, and people's evident valuations of themselves and of others are systematically related to the parties' reproductive values".

[48] Numerous studies suggest how inclusive fitness may work amongst different peoples, such as the Ye'kwana of southern Venezuela, the Gypsies of Hungary, and the doomed Donner Party of the United States.

These misunderstandings don't just crop up occasionally; they are repeated in many writings, including undergraduate psychology textbooks—most of them in the field of social psychology, within sections describing evolutionary approaches to altruism.As with the earlier sociobiological forays into the cross-cultural data, typical approaches are not able to find explanatory fit with the findings of ethnographers insofar that human kinship patterns are not necessarily built upon blood-ties.

However, as Hamilton's later refinements of his theory make clear, it does not simply predict that genetically related individuals will inevitably recognise and engage in positive social behaviours with genetic relatives: rather, indirect context-based mechanisms may have evolved, which in historical environments have met the inclusive fitness criterion.

[31] Under this perspective, and noting the necessity of a reliable context of interaction being available, the data on how altruism is mediated in social mammals is readily made sense of.

[57] How developing zygotes differentiate between full siblings and half-siblings in the ovary is undetermined, but genetic interactions are thought to play a role.

The evolutionary emergence of single-ovulated ovaries in plants has eliminated the need for a developing seed to compete for nutrients, thus increasing its chance of survival and germination.

[56] Kin selection may play a role in plant-pollinator interactions, especially because pollinator attraction is influenced not only by floral displays, but by the spatial arrangement of plants in a group, which is referred to as the "magnet effect".

[62] The study design for this experiment included planting establishing pots of M. moricandioides with zero, three or six neighbors (either unrelated or half-sib progeny of the same mother) and advertising effort was calculated after 26 days of flowering.

[67][68] The root exudate allantoin produced by rice plants, Oryza sativa, has been documented to be in greater production when growing next to cultivars that are largely unrelated.

[73][74] Those ideas were mostly ignored until they were put forward again in a series of controversial[20] papers by E. O. Wilson, Bert Hölldobler, Martin Nowak and Corina Tarnita.

Inclusive fitness theory is an unnecessary detour, which does not provide additional insight or information.They, like Alonso and Schuck-Paim, argue for a multi-level selection model instead.