One of the most fascinating aspects of the world of biology is animal behavior. The study of animal behavior is known as ethology. The job of an ethologist is to “determine what causes instinctive behavior, how such behavior developed over millions of years, and how it helps a species survive” (Rumbaugh World Book). A common tool for an ethologist to use is “an ethogram, which is a list that describes the known behavior patterns of the species. . . .Ethologists have developed ethograms for various species of insects, fishes, birds, and mammals” (Rumbaugh World Book). Ethograms are useful tools for tracking patterns of behaviors, and there are certainly a variety of behaviors that are worth studying. Throughout the history of ethology scientists have tracked the nuances of animals’ behavior such as feeding and mating, but perhaps one of the most fascinating aspects of ethology is that of animal altruism.

In ethology, the behavior of an animal “is said to be altruistic if it has the effect (not purpose) of promoting the welfare of another entity, at the expense of its own welfare” (Dawkins, Extended 291). As humans, we are used to the concept of altruism in our own social behavior, but altruism in animals may seem a bit out of the ordinary. In fact, altruism in different species of animals is exactly what we should expect, and altruism is more widespread than the casual reader might imagine. Throughout the entire animal kingdom we can find examples of altruism; a history of the ideas of altruism leaves us with two types of altruism called kin selection and reciprocal altruism.

Before examining specific cases of altruism, the basic history of altruistic studies should be examined. After Darwin put forth the idea of natural selection in 1859, the idea of altruism in animals seemed rather inconsistent with his theory. After all, why should animals ever act in another’s interest? Theoretically every individual should have behavior that is basically selfish. The reason for this, at the time, was that the individuals that use all the materials they can for themselves and look only after themselves should profit by surviving and reproducing more than those who behave altruistically. Arguably there would be a case for parents to take care of their young still, for reproduction itself is useless unless the parent can ensure the survival of their own lineage. Because of this, we do have a reason for parents to behave altruistically toward their young. Animals, however, did not and do not just behave altruistically toward their young. In fact, in many species, the act of altruism extends far past the genetic offspring of an individual. Many species of insects, for example, take up different roles in social colonies. Some insects are born with roles in which they never even have a chance for reproduction. Another striking example of altruistic behavior is “the discovery of long-term lesbian relationships in monogamous birds” (Trivers 199). Quite often, in fact, female gulls will “stay paired in successive seasons” (Trivers 199). Examples for altruistic acts such has these required an explanation from evolutionary biology as to why they should exist.

The earliest ideas were those of species selection. Species selection can be described as “a kind of natural selection at the species level” (Dawkins, Watchmaker 265). In the idea of species selection, the entity that is considered to survive or fail is not the individual itself but the entire species. This idea was used to solve the problem of altruism within animals of a species. The logic presented was that if there was cooperation amongst individuals in a species, that species would survive better. The argument for species selection is appealing, but flawed, for what if a single individual of the species rebelled against the idea of cooperation? An individual that refused to yield resources and energy to the animal’s companions in favor of the individuals own reproductive success would indeed come out ahead because that individual would produce more offspring. As a result, animals with similar traits for acting in self interest, as opposed to group interest, would become more prevalent in a population. The fact that species selection does not hold up would indeed be troubling, for altruism in animals still needed an adequate explanation. Finally, however, a reason for altruism was found. The primary unit of selection is not at the level of the individual or the species, but at the gene itself. An important differentiation to make between individuals, species, and genes is that genes are replicators. Arguably organisms do replicate as well, but their instincts for reproduction are guided by genes and therefore reproduction is an effect or phenotype of an animal’s genes. In fact, genes are what determines how the organism is ultimately constructed as is apparent by modern day genetics (there are, of course, environmental factors at work as well). Genes, as replicators, are naturally selected upon based on their ability to survive. Genes can survive a variety of different ways, but in dealing with animal altruism the only methods that we truly need to look at are those that survive by promoting certain phenotypes that encourage the genes replication. There is reason to note that this process does not necessarily have to include genes; any replicator that can be selected upon will undergo similar processes of evolution. Richard Dawkins, in his publication of The Selfish Gene so bold as to suggest “that a new kind of replicator has recently emerged on this very planet” (192). Dawkins’ idea of the “meme” has currently taken a strong foothold in the scientific community.

So why are the ideas of replicators and their resulting phenotypes so important? The dynamics that we find in a replicators success is important in the field of theoretical biology; this field can give us the underlying reasons as to why animals should act in altruistic ways toward each other. Theoretical biology gives two different types of altruism that can be applied to the animal kingdom. Kin selection “states that individuals can transmit copies of their own genes, not only directly, through their own reproduction, but also indirectly, by favoring the reproduction of kin, such as siblings or cousins” (Keller & Chapuisat 899). Reciprocal altruism, on the other hand, is the concept that, over an extended period of time, genes for cooperation will survive better than non-cooperative genes. There is another way that animals may be found to act altruistically called social parasitism. In this method the “recipient induces altruism that would normally be directed elsewhere or not displayed at all” (Trivers 49). As the name implies, this type of altruism is actually more a type of manipulation, so I will focus on kin selection and reciprocal altruism.

The first type of altruism that we may look at in detail is that of kin selection. Before examining specific cases of kin selection, I feel the reader may profit from an explanation of the underlying principles of kin selection. The basic idea of kin selection is that animals with similar genes (close relatives) will act altruistically toward each other because, in acting altruistically, they are ensuring more copies of their own genes get passed. A gene that promotes an organism to act altruistically toward a close relative will spread well because it is very likely that the gene is aiding the survival of another copy of itself inside the body of the organism’s relative. More specifically, if the close relative is a sibling we would expect a fifty percent chance that the gene is found in that sibling. The reason being that the first organism “must have received [the gene] from. . .[the organism’s] father or. . .[the organism’s] mother” (Dawkins, Selfish 90-91). Since organisms receive half their genes from the mother, and half from the father (in most cases), the gene has a fifty percent chance of being in each of the offspring. This leads to a sort of selective kin selection. Using the same logic as I did with siblings, cousins have a 1/4 chance of sharing any particular gene; nieces and nephews carry a 1/3 chance of sharing a gene, and the list continues. A formula to calculate whether or not it is in the best interest of the gene for an animal to perform an altruistic act is Br>C; in this formula,“B” is the benefit received by the individual,“r” is the likelihood that the same gene is found in the one receiving the altruistic act, and “C” is the cost of the organism that is acting altruistically be the cost in time, resources, or safety. This formula was developed by William Hamilton who is regarded as “a leader of what has been called ‘the second Darwinian revolution,’ a group that includes evolutionary theorists Richard Dawkins and John Maynard Smith” (Woo A.20). The formula not only holds up mathematically, but can be applied to the world of the animal kingdom.

A simple example of kin selection in the animal kingdom comes from Belding’s ground squirrels. This species is found hibernating for most of the year and spends “only 3-4 months above ground in the summer” (Mateo online). Because so much time is spent in hibernation, competition among the males is fierce as far as mating. In addition to this fierce battle of mating, these ground squirrels are heavily preyed upon by a variety of different predators. Among newborn ground squirrels, “only 40-60%” are expected to survive the summer (Mateo online). Of those that do survive, the males will “leave home by late summer, settling 250-500 m away from where they were born. Females stay where they were born and as a result live near relatives” (Mateo online). Belding’s ground squirrels often perform the altruistic act of sounding an alarm call when a predator lurks near. This call can be fatal for the caller because “13% of callers are stalked by predators,” while only “5% of non-callers” are stalked (Brugam online). These calls are almost never performed by male ground squirrels because they rarely have any close relatives in the area. Instead alarm calls are sound by the female “if they have close kin living nearby” (Mateo, online). By sounding these calls, female squirrels are “helping their relatives to survive and pass on genes they share in common” (Mateo, online). As a result, ground squirrels with the instincts to sound warning calls at their own risk when close kin are near become prevalent in the ground squirrel population.

A type of animal that shows an especially large amount of altruism due to kin selection is a eusocial animal. A eusocial species is a species in which organisms other than parents care for the young, there are overlapping generations of organisms, and there are sterile castes. Up until the twenty first century, the only species that were known to display these traits were insects including ants, wasps, and bees, but recently scientists agree that the naked mole rat is “the first undeniably eusocial mammal known” (Sivitz 356). In naked mole rats, and eusocial animals in general, “one female naked mole rat in a colony of about 80 animals does all of the breeding” (Sivitz 356). This is also the case in ants; one female in a colony, the queen, gives birth to all the ants of the colony. Sterile worker ants do not reproduce. These ants may fulfill a variety of roles in the colony; some serve as soldier ants or foragers, while other ants may take on roles as specific “as living doors. . . and as living storage organs” (Trivers 172). Although these ants may seem to take on a very cooperative communal life, in actuality “life within colonies also entails conflict” (Aron et al. 1308). The conflict, as we shall soon see, stems from an interesting competition among ants to pass along their genes. Ants are haplodiploid; when the queen of the nest lays eggs, the eggs that are unfertilized develop into males that are haploid. Females, on the other hand, are the result of fertilized eggs and are therefore diploid. This presents an especially interesting case in kin selection. In this special case all males that fertilize eggs cells can be certain that they will pass all their genes to the next generation, barring any mutations in the genetic process. All the eggs that the male does fertilize have a ¾ relationship to each other because they share all of their father’s genes, and have a fifty- percent chance of sharing any gene of their mothers as well. Unfertilized eggs, males, have a ½ relationship with each other because they have a fifty percent chance of sharing genes from the mother; in males relationship to their sisters, the degree of relatedness is ¼ because males are fatherless and do not have half the genes that females do. The genes the males carry have a one hundred percent chance (with the exception of mutations) of being shared in the mother, and the mother shares approximately ½ of the genes with her daughters. Thus as a result of haplodiploidy we have sisters with closer genetic relationships to each other than their own mother! Since sisters are more closely related than offspring, but less than brothers, female ants will develop to care after their sisters whenever possible. Indeed scientists have seen “good evidence that ants often invest more energy in the production of females than males” (Trivers 178).

Referring back to the conflict between ants, we’ll notice that the queen ant will share all of her genes with her sons, while the daughters of the queen share only a ½ relationship to the sons. In contrast, the queen shares only a ½ relationship with her daughters while sisters share a ¾ relationship with each other. This produces a “conflict between mother and offspring . . . over male reproduction” (Trivers 179). The female workers will not, of course, harm the queen in any way because in doing so they would destroy the female that produces offspring with a ¾ genetic relationship to themselves, so the workers do, in fact, protect the queen, valuing her life even above their own. The conflict arises between the workers desire to raise females, and the queens desire to raise males with a closer genetic relationship. The workers will ultimately be able to raise more females, but some males are naturally needed to keep the colony going, and recent “findings suggest that queens can force workers to raise male sexuals by limiting the number of female brood and [the findings] help to explain why sex investment ratios tie between the queen and worker equilibria” (Passera et al. 1308). None of this is to say, of course, that ants have any conscious desire to produce certain sexes, and I hope the reader will not take me too literally. The appearance of such behavior as queens trying to produce an excess of sons naturally arises because genes that are passed to sons have higher rate of carrying her own genes; thus a gene that says “make a lot of sons” will take well because that gene will be passed on better when sons are made. The roles of ants, of course, are an extreme example of kin selection where kin share so many genes that a natural cooperative bond is formed among organisms. Ants and other eusocial animals have been likened to giant “super-organisms” rather than separate individuals.    Reciprocal Altruism is the other main type of Altruism that notes explaining. The theory of reciprocal altruism “was presented [in 1971] by Prof. Robert Trivers” (Kevles 40). The theoretical principal of reciprocal altruism can be explain by a game called the “Prisoner’s Dilemma.” I use this example because many theoretical biologists “rely extensively on the iterated Prisoner’s Dilemma game to model reciprocal altruism” (Stephens 533). Although it might be arguable that there are also “alternate games which meet the informal conditions on reciprocal altruism, and which yield both quantitatively and qualitatively different predictions,” as discussed in Christopher Stephens paper “Modeling reciprocal altruism,” I will still only show the basic game of Prisoner’s Dilemma as the game displays the most basic example of reciprocal altruism (533). The point should be noted, however, that theories predicting “different stability characteristics for various strategies” also exist (Stephens 533). Imagine that two organisms are offered the chance to either cooperate with each other, or to act selfishly and defect. If both players cooperate, both receive a set valued pay off; we’ll say the payoff is the quantity of four. If one player cooperates, and the other defects, the defector gets six points, and the cooperator (perhaps a better word would be “sucker”) gets negative two points. If both defect, each receives one point. The game itself is modeled on a four by four grid.

Obviously if any organism was to play the game one time through, the best option would be to be “defect.” If the opposing organism cooperates, the defector would reap a six point benefit; if the opposing organism defects, the original organism would gain only one point, but avoid a negative payoff. The question then arises of how any type of altruism could arise from this game. The answer is the end result of different organisms playing the game multiple times with each other. In a condition where both organisms have a chance to enter an ongoing set of situations like the game “Prisoner’s Dilemma,” the organisms that cooperate with each other receive a higher benefit (more points) than organisms that continually defect. Thus any organisms that can maximize their “points” through cooperation will come to be more prominent in the population, so we see that the genes that survive the best in a population are the ones that have coded for cooperation. Of course, the organism must be prepared to discriminate between those organisms that cooperate, and those that defect, for in a population of pure cooperators an organism with a tendency to defect would be wildly successful. This problem shows that any cooperative organisms in a population must be able to tell the difference between those who will repay cooperation, and those who will defect when the timing is right. The organism should carry a grudge against any known defectors. Robert Axelrod, an American political scientist, “had the entertaining idea of running a competition [for the game of prisoner’s dilemma], and he advertised for experts in games theory to submit strategies . . . entries in computer language” (Dawkins, Selfish 208). Each entry was allowed to compete against each other contestant, itself, and a random simulator. The best strategy, however, was the strategy of “Tit for Tat.” This strategy played cooperate every time, except after the opposing player played defect, in which case Tit for Tat would play defect on the following turn. Thus we can see that the Tit for Tat strategy works well in theoretical biology, and the strategy should work well in the natural world, producing organisms of cooperative, but discriminating organisms.
   
Reciprocal altruism is an exceptionally interesting field of study in the animal kingdom. Unfortunately, “few cases [of reciprocal altruism] have been well documented” (DeNault & McFarlane 855). Among all of the organisms that display reciprocal altruism, vampire bats are among the most well known, and the most fascinating. Vampire bats must feed “at least once every two nights, or they will die,” yet often several bats do not find food during the night (Kevles 40). Despite the fact that many bats miss out on getting their own mean, several bats survive because successful bats “regurgitate blood to their hungry chums, sharing nourishment with related and unrelated bats alike” (Kevles 40). Gerald Wilkinson was a professor who “studied food sharing in D. Rotundus extensively” (Davidson online). In Professor Wilkinson’s study, Wilkinson caught several bats and held them without food for a night. In doing this, Wilkinson discovered that “most of these [bats] were fed by their roost mates soon after being returned to them, while well-fed bats that were returned to their roost mates were never fed” (Trivers 364). So with Wilkinson’s data we see that reciprocal altruism is commonplace and, in fact, quite necessary in the case of vampire bats. Unfortunately the effects of defecting from cooperation were not tested by Wilkinson.
   
Many primates also display the behavior of reciprocal altruism. Even in extreme cases of “personal peril, a male baboon helps another male fight off a third” (Tangley 53). Several other types of primates such as “gibbons and chimpanzees . . . offer food to others after solicitation” (Strong online). A detailed explanation of several examples of reciprocal altruism can be found in Robert Trivers’ book Social Evolution. Frequently animals with a high degree of intelligence such as primates (dolphins are also worth noting) display complex social patterns. These animals frequently communicate amongst each other in many ways, and may bond with each other through actions such as grooming, and they are quite ready to hold grudges against each other for a lack of cooperation.
   
All of these examples show that altruism can be found throughout the animal kingdom in the forms of reciprocal altruism and kin selection. Kin selection works because animals that are closely related can work together to pass along the same genes, and reciprocal altruism works because animals that cooperate over many separate instances have a chance to yield more benefits than those that act purely in self interest. Both of these examples are important to consider in studying animal behavior, and ourselves, for the “emotions of friendship, moralistic aggression, gratitude, and sympathy, as well as our sense of fair-ness, probably arose primarily as mechanisms to regulate reciprocal altruism” (though I do feel the need to cross Trivers statement with the work of Dr. Susan Blackmore on memetics; perhaps our behavior may be a sort of common ground) (Trivers 393-4). To sum it up, we can see many examples of this fascinating result of the selfish replicators of genetics. These small molecules that are selected based on selfish properties of replication can create organisms with very non-selfish behavior, and the study of this behavior can explain the properties and intricacies of altruism in the animal kingdom.


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