The Evolution of Altruism and What it Means

The earliest evidence of ceremonial burial suggests it originated around 80 thousand years ago (KYA).  While this may excite the interest of the archaeologist studying religion and culture, ceremonial burial also provides one of the earliest examples of altruism in humans because the individual must have exhibited selflessness in order to care for the Other [1].  In humans, altruism may date back to 150 KYA, as the brain arrested its continued increase in size around that time.  In conjuring reasons for this halt in brain growth, Kat McCormick suggested that the adaptive advantage of increased intelligence that had driven much of the increase in brain size for the time before 150 KYA ceased to be an advantage, as other mental states related to sociability developed such as compassion, guilt, and (the focus of this paper) altruism (1; 2).

Another Bi-Co alumna, Caitlin Costello wrote that a simple definition for altruism is to be generous by, “seeking the welfare of others.” [3]  This definition remains too broad, however, as it leaves processes such as sexual reproduction to be labeled as altruistic since the action helps the well being of others in the form of one’s progeny.  Therefore, a more operational definition of altruism involves benefitting others, as well as sacrificing some well-being or fitness on the part of the altruist [4].

In terms of evolution by natural selection, altruism is not a favorable trait, as it decreases the fitness of the altruistic individual at the benefit of another individual [12].  Nevertheless, W. D. Hamilton (1964) derived a quantitative explanation that suggests the likelihood of altruism is contingent on the relatedness of the two interacting individuals.  Specifically, his notion of Kin Selection proposed that altruistic behavior will be favored if the two individuals are related closely enough that the fitness benefit of the recipient exceeds the fitness cost of the altruist because the altruist will support the proliferation of his shared genes. Therefore, kin selection may not only be limited to immediate family, but may apply to the relationship between any two organisms sharing a gene or a trait regardless of phylogenetic distance, such as the green beard gene exemplified by Richard Dawkins (1976), [5].  For instance, sterile worker ants in a colony devote their energy to the well being of the Queen, since only she harnesses the ability to promulgate their shared genes.  When the social amoeba Dictyostelium discoideum is stressed for food, some of its cells in the fruiting body change into a ‘slug’ that will proliferate the genome, while other cells become determined as support that will not persist even though all of the genes in the fruiting body are genetically identical [6].

While the Kin Selection model may provide an acceptable explanation for altruism in non-humans, in humans, altruism becomes a much more complicated aspect to study.  First, Costello (2004) argues that while in other animals, the decision for altruism often determines life or death, the gravity of such decisions is often absent, as many altruistic and non-altruistic actions do not involve life and death.  Therefore, the relevance of altruism for the organism will be significantly different among species.  Second, the complexity of the human mind is responsible for powerful emotions such as compassion, empathy, and sex favoritism that complicate the altruistic impulse to help one similar to oneself [3].  These two factors may help to explain why in humans specifically, kin selection altruism also uniquely involves two more facets: 1) reciprocal altruism, the expectation that an altruistic action will be rewarded later; and 2) altruistic punishment, the reprimanding of individuals who do not abide by the group’s altruistic expectations [7].  Neurological evidence from fMRI scans of humans undertaking charitable tasks suggests that the same mesolimbic reward system of the brain is activated that correlates with the same part of the brain that activates in response to the reception of charitable action.  Significantly, however, this ‘altruistic’ behavior correlates with activity in the areas of the prefrontal cortex that are not activated with selfish behavior [8].

In assembling my story concerning the evolution of altruism, I have acquired several reservations that fall into three distinct categories of biological, philosophical, and sociological concerns.  From my knowledge of biology, I worry that the notion of altruism has become too intertwined with the worship of the gene by proponents such as Dawkins (1976).  For instance, it seems that both presented examples of altruism in non-humans (e.g. ants and slime mold) are based on the “selfish gene” assumption that proliferation of genes is the underlying motivator for altruistic behavior.  While genes seem to bear significant clout in altruism, the effects of non-genetic effects on heredity should not be overlooked.  Many epigenetic and ontogenetic changes occur during an organism’s development that may become hereditary and transmitted vertically or horizontally to other organisms [9,10]. In light of this evidence, when examining altruism, studies should also consider the non-genetic hereditary factors.

Although Moll et al. (2006) made a valiant effort to demonstrate a neurological basis to what they defined as ‘altruism’ in humans, it seems altruism from an evolutionary perspective in humans remains so fundamentally complex that any neurophysiology that attempts to pinpoint the one protein or structure responsible for ‘altruism’ will provide too narrow an understanding.  Specifically, based on other evidence presented in this paper, human altruism cannot be defined in terms of kin selection, but also obeys a superimposed sense of reciprocal altruism as well as altruistic punishment.  Therefore, to grasp it neurobiologically would entail a detailed methodology focused on each aspect of altruism that then synthesizes these node results into a network that can account for the more broad understanding of altruism.

From a sociological vantage, it seems that the definition biologists have ascribed to ‘kin’ in the understanding of kin selection and altruism especially in humans is too narrow.  It assumes, in line with an assumption from Dawkins (1976), that kin is strictly understood through genetic relationships.  While this may hold for non-human animals, human kin is often not strictly understood in a genetic sense.[11]  With social inventions, such as adoption, divorce, and remarriage, the affinity that two individuals in human society may share may transcend any genetic relationship they may share to a more abstract relationship.  For instance, two boys in a family may not be closely related by genetics if one is adopted.  Nevertheless, they may form a stronger kinship bond than one of the boys will with his maternal cousin who is closer genetically than his brother.  Therefore, applying a notion of kin to humans must be examined in light of complex sociological relationships.

Throughout my story, I reflect that most of my reservations arise from studies pertaining to altruism studies in humans, while in non-human organisms I seem to bear less reservations about the conclusions.  I attribute my complacency with the non-human results to my perception of non-human organisms as Other, while the implications of studies on Humans brings a plethora of personal experience and observation intersecting with what is often perceived as an ‘objective’ biological study that I believe my reservations were heightened.

Works Cited


[1] McCormick, Kat (2004) “Altruism and the Fluctuation of Intelect” Serendip, the server home page, /sci_cult/evolit/s04/web1/kmccormick.html, accessed 9 May 2009.

[2]Mayr, Ernst.  What Evolution Is. New York: Basic Books, 2001.

[3] Costello, Caitlin (2001) “Altruism: selfless or selfish?” Serendip, the server home page, /bb/neuro/neuro01/web2/Costello.html, accessed 9 May 2009.

[4] Wilson, EO. Sociobiology: the New Synthesis. Cambridge: Harvard University Press, 1975.

[5] West, Stuart, Gardner, Andy, and Ashleigh Griffin. Altruism. Curr. Biol. 16:13: 482-483. 2006.

[6] Strassmann, Joan, Zhu, Yong, and David Queller. Altruism and Social Cheating in the social amoeba Dictyostelium discoideum. Nature. 408: 956-961. 2001.

[7] Fehr, Ernst and Urs Fischbacher. “The nature of human altruism.” Nature. 425:785-791. 2003.

[8] Moll, Jorge, Krueger, Frank, Zahn, Roland, Pardini, Matteo, de Oliveira-Souza, Ricardo, and Jordan Grafman. “Human fronto-mesolimbic networks guide decisions about charitable donation.” PNAS. 103:42:15623-15628. 2006.

[9]Gilbert, SF (2001) Developmental Biology: 8th Ed.  (Sunderland, MA: Sinauer and Associates, Inc.)

[10]West-Eberhard, MJ (2003) Developmental Plasticity and Evolution. (New York: Oxford University Press)

[11]Dawkins, Richard. The Selfish Gene: 1st Ed. New York: Oxford University Press, 1976.

[12] Evans, Nancy (2004) “Biology and Morality: Evolution or Inherency?” Serendip, the server home page, /sci_cult/evolit/s04/web1/nevans.html, accessed 9 May 2009.