Fall - 2012 Altruism1

Published on December 6th, 2012


On Altruism

By Tor G. Jakobsen, NTNU

There are five types of rationally motivated sacrifices a person will do. By taking into account altruism, researchers can become better at explaining seemingly irrational behavior.

First, one has a sacrifice with the expectation of reward. One obvious example is effort put into work, which often will be rewarded financially or otherwise. As was so eloquently put by the fictional character Gordon Gekko in the film Wall Street: “greed, for the lack of a better word, is good”. This is the rationale behind capitalism; greed will lead people to work harder to the benefit of society.

Of course, greed can also be destructive, as described by Paul Collier and Anke Hoeffler in their famous article entitled “Greed and Grievance in Civil War”. The point they made was that factors associated with greed provide a better explanation for the occurrence of civil war than so-called grievance factors, that is, feelings of injustice or repression. Collier and Hoeffler argue that each individual makes a cost-benefit calculus, and the higher their income from non-violent activity, the higher the potential reward form rebellious activity must be for them to quit their daytime job.

In other words, whether the expected utility (EU) of rebellion (R) is greater than the expected utility of keeping ones daytime job (D) is a function of both the income level, potential reward for rebelling, and the perceived probability of success. Thus, the richer a person is the lesser the chance of rebellion is, or EU(R) < EU(D), and the larger the reward of rebellion is and the greater the chance of success is, will imply an increased probability of rebellion, or EU(R) > EU(D).

Second, there is a sacrifice that in essence is a very minor sacrifice toward people that are neither relatives nor friends. The rationale behind this is that the positive action cost only marginally more than a neutral or a negative action, and though no reward is expected, there is a possibility of positive feedback in the form of a return of favor from the recipient, achieving a reputation of being a likeable and generous person, or by heightening ones own self-image. An example would be the act of donating blood, or something more trivial like offering ones seat to a pensioner at the subway.

Third, there is the sacrifice a person will make for the benefit of persons one regards as ones friends. The rationale will be a return of favor, whether they be of a larger or a lesser extent than the original sacrifice. In essence, one needs allies, and two works better than one, so even though a favor is not fully returned, in sum such an arrangement will be to the benefit of both parts.

Charles Darwin (1809–1882)

Fourth, and most important for the topic of this article is the sacrifice made for a relative. For sure, this kind of sacrifice bare with it many similarities to that of sacrificing for a friend. However, a sacrifice to a family member or a relative will more than often be of a much greater extent than to that of a friend, regardless of whether the relationship with that certain relative is better or worse than with that of a given friend.

And this is where our genes play an important part.To explain why one will make a bigger sacrifice for a relative than for a friend or an acquaintance, let us go back to the 19th century. Following the logic of Charles Darwin it should be selfishness rather than altruism that should evolve. The underlying logic being that if altruistic individuals sacrifice themselves for others in their tribe, their altruistic genes will not be passed on. Even so, there are numerous examples of altruistic behavior both among humans and animals. An illustrating example would be the behavior of a squirrel in the presence of a feline, who will risk his own safety by warning other members of his tribe about the danger.

Another one would be when hyenas hunt in pack. They have a strategy that involves members of the group often breaking limbs, which in nature means death, for the greater good of catching a prey for all the hyenas to feast on. Both examples are definitively beneficial to the group or tribe as a whole, but would imply the death of the altruistic member, thus stopping its ability to spread its genes. The same would go for those willing to fight for their nation in wars, a noble act which the whole tribe benefits from, but for the member fighting it is not directly beneficial.

Well, sacrificing oneself for ones tribe does make sense from an evolutionary point-of-view. Obviously, altruistic actions directed toward ones own offspring, like parental care, is easy to see the logic of. The survival of one’s own offspring ensures the spread of ones genes. But why would a person risk his or her life for other people who are not necessarily their children.

This puzzle was solved by the New Zealand-born evolutionary biologist William D. Hamilton. Altruism or sacrifice will occur if this is beneficial for the members gene flow, that is, its not the member of the group that is important, but the genes. The basis for Hamilton’s argument is the coefficient of relationship. This measure is obtained by summating the coefficients calculated for every line by which two subjects, whether they be humans or animals, are connected to their common ancestors. It was defined in 1922 by the geneticist Sewall Wright whilst working for the U.S. Department of agriculture. It was originally meant to be an instrument to avoid inbreeding of domestic animals.

Table: The coefficient of relationship




100 %

identical twins


50 %



50 %



25 %



25 %

half siblings


25 %



12.5 %



6.25 %



3.13 %

second cousins


The coefficient of relationship is the key here. William Hamilton thus stated what we know as Hamilton’s rule, which implies that for all species, sacrifice or reduction of aggression will occur when   rb – c>0, where r is the r-coefficient which identifies how related to individuals are, b is how much the beneficiary benefits from the sacrifice (or more specific, how much his or her gene flow benefits from it), and c is the sacrifice from the altruistic member of the tribe. To explain this formula, let us start with the example of how sacrificing ones life to save the lives of others can make perfect sense from an evolutionary perspective.

Naturally, sacrificing your own life for someone unrelated would not at all make sense, since that person share few of your genes, and you loose all of yours. However, taking a look at table X things might get clearer. If you sacrifice your life so that three full-siblings save their lives, this would make perfect sense according toHamilton’s rule, as siblings on average are 50 percent identical. So by sacrificing 100 percent of you, you thus save 3*50 or 150 percent of you:

rb – c>0 –> (3*0.5*1)-1=0.5 –> 0.5>0

The same would apply if you saved five nephews and nieces, or nine cousins, or 17 second cousins. To complicate the equation one could include examples of altruism that does not imply sacrificing ones life. Let us use the example of Martin, faced with the option of donating a kidney to his niece. Receiving a kidney is essential for the niece, whom is 25 percent similar to Martin. Donating a kidney is a large sacrifice, yet nothing near comparable to the benefit of receiving it. The calculation according toHamilton’s rule is as follows:

rb – c>0 –> (0.25*0.8)-0.1=0.1 –> 0.1>0

The benefit for the recipient is set at 0.8 since there is a chance of receiving a donor kidney form another person. The sacrifice of donating the organ is set at 0.1, thus giving Martin an evolutionary reasoning for the organ donation. Of course, other factors play a part, like personal relationships, sheer goodness etc. ButHamilton’s rule is definitely a factor, which becomes clear when thinking about why people choose to sacrifice themselves for, let’s say, a village, or even a country.

Misunderstood altruism can also be used to explain many of the most horrific acts of war and terror. It would have made sense being a kamikaze pilot hadJapanwon the war (again, from a genetic point of view). Suicide bombings can also be explained, if one takes into account the twisted mind of the perpetrators, who undoubtedly believes that by sacrificing themselves and killing what they believe to be the enemy, will be for the greater good of their people.

A fifth type of altruism is the one where one will make a significant sacrifice of a stature similar to that of a relative, is that to a person to whom one is physically attracted. This type of altruism needs no further explanation, as the mechanism explaining this action is relatively similar to that of altruism toward a relative.

In other words, increasing the probability of spreading ones genes with an acceptable partner. For sure, there are other types of sacrifices one can make, but the five types mentioned in this section are the ones that are rationally (at least in the mind of the sacrificiant) motivated, either from the expectation of reward, or for the purpose of spreading ones genes.


Explaining seemingly irrational behavior

Going back to the mechanism demonstrated by Hamilton’s law, this perspective brings new light to several unsolved mysteries of the social sciences. For example, many political scientists have been puzzled by the high level of cooperation in situation set up as game theory models.

The very basics of method can be illustrated through what is known as prisoner’s dilemma. To use the two editors as example of this game, let us assume that Tor Georg and Joachim have been brought in by the police under suspicion of a bank robbery. Let us also assume that Tor Georg and Joachim are guilty of this bank robbery, but the police lack evidence of it because they were masked during the heist. The two culprits are put into different interrogation rooms, with the police seeking to get confessions from them.

Table: Years in prison following confession or denial, two unrelated individuals

              Tor Georg
Confess Deny
Joachim Confess T=5, J=5 T=10, J=1
Deny T=1, J=10 T=2, J=2


The two robbers cannot communicate, and are presented with the following options by their respective interrogators:

- If you confess to the robbery and the other person do not, you will serve one year in prison. If you do not confess and the other suspect confesses, you will get ten years. If you both confess you will get five years, and if you both deny you will get two years.

The logic of the game is that both Tor Georg and Joachim’s best option is to confess, regardless of the action of the other one. However, this will, if both persons are rational, result in a sub-optimal outcome, that is, both will receive five years in prison rather than just two years (which is the option if both denies). Of course, both Tor Georg and Joachim are rational actors, and thus end up in prison for five years.

However, often people will choose to cooperate, which seemingly contradicts the rational actor perspective. The reason suggested by some game theorists is that humans have developed a tendency to cooperate with members of their own ethnic groups.

The logic behind this draws us back to Hamilton’s rule, that is, one has a natural tendency of altruistic behavior toward people to whom one is related. In the example with Tor Georg and Joachim Hamilton’s rule would not apply, considering that they are not relatives. If we replace Joachim with another person, namely Jo, who is Tor Georg’s brother, we would suspect another outcome of the game. The relationship-coefficient for full-siblings is 0.5, that is, 50 percent of Jo is Tor Georg, and vice versa, which changes the pay-offs of the game.

Table: Years in prison following confession or denial, two full-siblings

              Tor Georg
Confess Deny
Jo Confess T=7.5, J=7.5 T=10.5, J=6
Deny T=6 J=10.5 T=3, J=3

In essence, this implies that the genes of each participant will get 100 percent of his own prison sentence, but also 50 percent of the other person’s sentence (since they have a 0.5 value on the r-coefficient). This increases the likelihood that people will cooperate, even though the seemingly rational thing to do is to defect. In the example shown in table X both will here choose to deny having participated in the bank robbery, and will end up with two years in prison each (which translates into three years in the language of Hamilton’s law). Cooperation is healthy because increases each participants reproductive potential.

The underlying logic of this can both be translated to, and make more sense, in games with many persons involved. The incentive to free-ride becomes smaller when several related individuals are involved in the game. This is the reason why altruism should be taken into account in scientific analyses dealing with humans.


Further reading:

Collier, Paul & Anke Hoeffler (2004) “Greed and Grievance in Civil War” Oxford Economic Papers, 56(4); 563–595.

Hamilton, William D. (1964) “The Genetical Evolution of Social Behavior, I & II” Journal of Theoretical Biology 7(1): 1–52.

Hammond, Ross A. & Robert Axelrod (2006) “The Evolution of Ethnocentrism” Journal of Conflict Resolution, 50(6): 926–936.

Jakobsen, Tor G. (2011) War: An Introduction to Theories and Research on Collective Violence. New   York: Nova.

Wright, Sewall G. (1922) “Coefficients of Inbreeding and Relationship” American Naturalist 56(645): 330–338.




Cover photo by Tambako, second photo by Jacob Bätter, fourth photo by Gord Webster.





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