Altruism (biology)
Cases of animals helping individuals to whom they are closely related can be explained by kin selection, and are not considered true altruism.
The existence of altruism in nature is at first sight puzzling, because altruistic behaviour reduces the likelihood that an individual will reproduce.
The concept of group selection has had a chequered and controversial history in evolutionary biology but the uncritical 'good of the species' tradition came to an abrupt halt in the 1960s, due largely to the work of George C. Williams,[10] and John Maynard Smith[11] as well as Richard Dawkins.
[16] Kin selection is an instance of inclusive fitness, which is based on the notion that an individual shares only half its genes with each offspring, but also with each full sibling (See footnote[nb 1]).
From an evolutionary genetic point of view it is therefore as advantageous to help with the upbringing of full sibs as it is to produce and raise one's own offspring.
Co-operative breeding (i.e. helping one's parents raise sibs—provided they are full sibs) could thus evolve without the need for group-level selection.
[2] In 1971 Robert Trivers[19] introduced his reciprocal altruism theory to explain the evolution of helping at the nest of an unrelated breeding pair of birds.
He argued that an individual might act as a helper if there was a high probabilistic expectation of being helped by the recipients at some later date.
Clearly (d) ("cooperation") is the best mutual strategy, but from the point of view of the individual betrayal is unbeatable (resulting in being set free, or getting only a two-year sentence).
However, in 1981 Axelrod and Hamilton[23] noted that if the same contestants in the PDG meet repeatedly (the so-called Iterated Prisoner's Dilemma game, IPD) then tit-for-tat (foreshadowed by Robert Triver's reciprocal altruism theory) is a robust strategy which promotes altruism.
[24][27][28] In the light of the Iterated Prisoner's Dilemma Game failing to provide a full answer to the evolution of cooperation or altruism, several alternative explanations have been proposed.
There are striking parallels between altruistic acts and exaggerated sexual ornaments displayed by some animals, particularly certain bird species, such as, amongst others, the peacock.
This led Amotz Zahavi to suggest that both might be fitness signals rendered evolutionarily stable by his handicap principle.
Similarly, in amateur golf, better golfers have fewer strokes subtracted from their raw scores than the less talented players.
It derives from the concept that the change in appearance and functionality caused by a non-silent mutation will generally stand out in a population.
[35][36][37][38][39] This will have the effect of a sexual population rapidly shedding peripheral phenotypic features and canalizing the entire outward appearance and behaviour so that all the members of that population will begin to look remarkably similar in every detail, as illustrated in the accompanying photograph of the African pygmy kingfisher, Ispidina picta.
Once a population has become as homogeneous in appearance as is typical of most species, its entire repertoire of behaviours will also be rendered evolutionarily stable, including any altruistic, cooperative and social characteristics.
[38] Its genes will therefore have only a very small probability of being passed on to the next generation, thus evolutionarily stabilizing cooperation and social interactions at whatever level of complexity is the norm in that population.
Humans and other animals exchange benefits in several ways, known technically as reciprocity mechanism.
No matter what the mechanism, the common thread is that benefits find their way back to the original giver.
Also known as the "buddy-system", mutual affection between two parties prompts similar behavior in both directions without need to track of daily give-and-take, so long as the overall relationship remains satisfactory.
Biological market theory is an extension of the idea of reciprocal altruism, as a mechanism to explain altruistic acts between unrelated individuals in a more flexible system of exchanging commodities.
Biological market theory consists of five formal characteristics which present a basis for altruism.
The applicability of biological market theory with its emphasis on partner choice is evident in the interactions between the cleaner wrasse and its "client" reef fish.
Cleaners have small territories, which the majority of reef fish species actively visit to invite inspection of their surface, gills, and mouth.
[45] Researchers tested whether wild white-handed gibbon males from Khao Yai National Park, Thailand, increased their grooming activity when the female partner was fertile.
[clarification needed][47] An example of altruism is found in the cellular slime moulds, such as Dictyostelium mucoroides.
