Overview[ edit ] In the science of ethology the study of behaviorand more generally in the study of social evolutionon occasion, some animals do behave in ways that reduce their individual fitness but increase the fitness of other individuals in the population; this is a functional definition of altruism. Cases of animals helping individuals to whom they are closely related can be explained by kin selectionand are not considered true altruism.
Overview[ edit ] In the science of Altruism and group behaviour the study of behaviorand more generally in the study of social evolutionon occasion, some animals do behave in ways that reduce their individual fitness but increase the fitness of other individuals in the population; this is a functional definition of altruism.
Cases of animals helping individuals to whom they are closely related can be explained by kin selectionand are not considered true altruism.
Beyond the physical exertions that in some species mothers and in some species fathers undertake to protect their young, extreme examples of sacrifice may occur. One example is matriphagy the consumption of the mother by her offspring in the spider Stegodyphus ; another example is a male spider allowing a female fertilized by him to eat him.
Hamilton's rule describes the benefit of such altruism in terms of Wright's coefficient of relationship to the beneficiary and the benefit granted to the beneficiary minus the cost to the sacrificer. Should this sum be greater than zero a fitness gain will result from the sacrifice.
When apparent altruism is not between kin, it may be based on reciprocity. A monkey will present its back to another monkey, who will pick out parasites; after a time the roles will be reversed. Such reciprocity will pay off, in evolutionary terms, as long as the costs of helping are less than the benefits of being helped and as long as animals will not gain in the long run by "cheating"—that is to say, by receiving favours without returning them.
This is elaborated on in evolutionary game theory and specifically the prisoner's dilemma as social theory.
Implications in evolutionary theory[ edit ] Cooperative hunting by wolves allows them to tackle much larger and more nutritious prey than any individual wolf could handle.
However, such cooperation could, potentially, be exploited by selfish individuals who do not expose themselves to the dangers of the hunt, but nevertheless share in the spoils.
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 s, due largely to the work of George C.
A group advantage e. If the selfishness is hereditary, this will ultimately result in the population consisting entirely of selfish individuals. However, in the s and s an alternative to the "group selection" theory emerged.
This was the kin selection theory, due originally to W. 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. The two activities are evolutionarily entirely equivalent. This quickly gained prominence among biologists interested in the evolution of social behaviour.
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. If, however, the recipients did not reciprocate when it was possible to do so, the altruistic interaction with these recipients would be permanently terminated.
But if the recipients did not cheat then the reciprocal altruism would continue indefinitely to both parties' advantage. West-Eberhard  and Dawkins  to be evolutionarily unstable because it is prone to invasion by cheats for the same reason that cooperative hunting can be invaded and replaced by cheats.
However, Trivers did make reference to the Prisoner's Dilemma Game which, 10 years later, would restore interest in Trivers' reciprocal altruism theory, but under the title of "tit-for-tat". The " game " has four possible outcomes: 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.
Remaining silent results in a four-year or six-month sentence. This is exemplified by a further example of the PDG: The mutually best ploy would be for both parties to order the cheapest items on the menu mutual cooperation.
But if one member of the party exploits the situation by ordering the most expensive items, then it is best for the other member to do likewise.
In fact, if the fellow diner's personality is completely unknown, and the two diners are unlikely ever to meet again, it is always in one's own best interests to eat as expensively as possible. Situations in nature that are subject to the same dynamics rewards and penalties as the PDG define cooperative behaviour:Acting with an unselfish regard for others doesn't always come naturally, even though many psychologists believe we're hard-wired for empathy.
After all, cooperative behavior . Members of a group of Japanese macaques grooming each other.
Grooming is a type of altruistic behaviour that can extend even to unrelated individuals when the behaviour is reciprocal and the giver's costs are smaller than the recipient's benefits. if kin altruism and kin-group selection were important, in-breeding(whichincreases theproportionsofgenessharedby kin) andnondispersal (whichkeepskinclosetogether)should beselectively advantageous.
However, mostplantsandanimals areadaptedforout-ratherthaninbreeding, andforeffective. Where human behaviour is concerned, the distinction between biological altruism, defined in terms of fitness consequences, and ‘real’ altruism, defined in terms of the agent's conscious intentions to help others, does make sense.
In the study of animal behaviour, altruism is seen in social animals when an individual willingly sacrifices itself for the better survival of the group. There are several theories about how this behaviour has come about under evolution by natural selection.
Where human behaviour is concerned, the distinction between biological altruism, defined in terms of fitness consequences, and ‘real’ altruism, defined in terms of the agent's conscious intentions to help others, does make sense.