- Sociobiology is the study of the biological basis of social behavior in organisms. Sociobiologists stress the organism of entire social populations over the behaviors of individuals.
- Scientists have been discussing concepts akin to sociobiology since the 1940s, and major thinkers – such as Hamilton and Williams – published theories of sociobiology in the 1960s. However, E. O. Wilson’s book, Sociobiology: The New Synthesis, propelled sociobiology into the mainstream, inspiring controversy.
- Sociobiology is centrally concerned with the origins of altruism in organisms, sexual selection and sexual conflict, and intragenomic conflict. Sociobiologists have attempted to bridge Darwin’s theory of evolution with observations of organism behavior.
- Although few scientists call themselves sociobiologists today, sociobiological methods continue to dominate modern animal behavior research.
In This Article
Sociobiology is the systematic study of how natural selection shapes the biological basis of all social behavior (Wilson, 1975).
Patterns of human social behavior can be explained by biological imperatives such as the drive to spread genetic inheritance as widely as possible.
Sociobiology distinguishes itself from evolutionary psychology, which stresses mental mechanisms more than genes as the evolutionary determinant of adaptiveness.
According to sociobiology, whole society traits are the outcomes of Darwinian evolution, and human as well as animal sociality depends on how genes and culture have co-evolved (Lumsden, 2011).
The early 1970s saw a significant theory of both theoretical and empirical approaches to the study of animal social behavior from an evolutionary perspective. Scientists hoped to understand social behavior in the same way that they understood morphological traits such as skin tone and eye color.
However, others saw the extension of an evolutionary perspective to human behavior as both politically dangerous and scientifically unsound (Segerstrale, 2015).
Sociobiologists assume that social phenomena – such as mating preferences, offspring sex ratios, warning calls, the treatment of young by parents, gregariousness, territorial defense, and so on – could be illuminated by the testing of hypotheses.
Sociobiologists are also selectionists, meaning that this uptake in certain traits could be explained by the assumption that the social attributes under consideration had been shaped by a history of Darwinian selection promoting the traits that would have made animals’ ancestors the fittest to reproduce.
As a consequence of William’s work, scientists began to see organisms as so-called “evolved reproductive strategists,” meaning that the attributes that organisms have can be understood as tactics for reproductive competition against others of their own kind.
Animals as well as non-conscious organisms such as plants, can have a reproductive strategy composed of certain reproductive tactics.
One idea that had a significant impact on sociobiology’s early history was William Hamilton’s concept of inclusive fitness or kin selection (1964).
Hamilton proposed that selection will favor any phenotype, or visible trait, that appears to be reflective of the organism’s own genes, regardless of whether these genes are in direct descendants or other relatives.
For instance, the brood care and colony maintenance of sterile worker ants can be selected for favorable if these acts promote the reproduction of a queen who is closely related to the workers.
According to Hamilton, selection maximizes the reproduction of the alleles of all those to whom the organism is related, not just his direct descendants. As a consequence, organisms are nepotistic (Alexander, 1979).
In his last chapter, Wilson argued that a number of human behaviors, such as sex roles, aggression, altruism, and even moral and religious beliefs, could have a biological basis (Wilson, 1975).
To support this argument, Wilson drew parallels to the behavior of other primates and invoked existing research on selected traits from human behavioral genetics and twin studies.
For the critical school of academics, this clearly supported a biologically deterministic view of humans, suggesting that because social inequality was “in our genes,” social reforms would be futile (Segerstrale, 2015).
The criticism of sociobiology soon escalated to a condemnatory letter signed by a number of Boston-area academics and an avoidance of researchers using this term to describe their work.
Robert Trivers followed this concept with papers on reciprocal altruism, parental investment, and parent-offspring conflict (1972).
The “Problem of Altruism”
One central concern of Sociobiology is the so-called “problem of altruism.”
The problem of altruism asks the question of how prosocial behavior, such as altruism, could have evolved as a restraint in aggressive conflict or in facilitating active cooperation.
Here, sociobiologists define altruism as actions whose average consequence is a reduction in the actor’s reproductive success and a direct increase in the reproductive success of someone else (Wright, 2015).
Unlike the definition of altruism used in everyday language, this definition treats the intent to help others as irrelevant.
On first look at Darwin’s theory of evolution, it would appear that selection would always penalize action that is altruistic; yet, many animals perform altruistic behaviors, such as helping to raise the young of others or taking some energetic or predatory risk to warn others of danger.
The most frequently cited answer to the problem of altruism is Hamilton’s inclusive fitness theory (Wright, 2015).
Hamilton’s inclusive fitness theory states that if the person who benefits from an altruistic act is related to the actor, and if that relative’s gain is large in comparison to the actor’s sacrifice, then the effect on the probability that the actor’s genes will be passed down is positive and altruism can increase in relative frequency.
Hamilton specifically proposed the formula, often called “Hamilton’s rule,” that an altruistic tendency will increase in prevalence under selection if r * b > c, where c is the cost to expected direct fitness that the actor must incur, b is the benefit to direct fitness by the beneficiary of the act, and r is the coefficient of relatedness between the actor and the beneficiary; the extent to which the actor and beneficiary have identical genes (Wright, 2015).
A large amount of sociobiological research focuses on testing whether altruistic behavior can be understood according to Hamilton’s rule.
Usually, supportive evidence shows that animals behave differently in correspondence to their relatedness to their interactants or neighbors.
For example, colonial ground squirrels and prairie dogs decide to call out warnings about predators depending on the caller’s degree of relatedness to the others around them.
In a similar sense, adult animals tend to only care for their own young, and those who help care for others’ young tend to discriminate by how related the young is to themselves (Daly and Wilson, 1988; Griffin and West, 2003).
Other research has focused on how animals can recognize kin when they behave nepotistically (Krupp et al., 2011).
In some cases, this discrimination is based on genotypical factors such as odor, while in others, there is merely a pattern of behavior that persists until they are more likely to move away from kin.
For example, a bird may behave cooperatively until they emigrate away from its colony after reaching maturity, a point where they are substantially less likely to encounter those they are highly related to (Wright, 2015).
Those who work in theoretical sociobiology have also tried to formulate solutions to the problem of altruism unrelated to relatedness. Many of these theorists use game theory models.
Animals, according to these models, are in a constant state of exchange, where favors are returned for ones promised in the future.
Nonetheless, despite attempts to dismantle Hamilton’s theory, it remains fundamental to theories of social evolution (Gardner et al., 2011; Queller, 2011; Wright, 2015).
Sexual Selection and Sexual Conflict
Sociobiological questions around sexual selection revolve around topics such as why organisms reproduce with two parents rather than by themselves and how and why males and females differ in species where there are multiple distinct sexes.
Darwin (1871) proposed, in his 1859 theory of evolution, that there is a direct evolutionary force called sexual selection. Sexual selection is an explanation for why some members of a species randomly have higher access to mates and reproduce with mates than others.
Darwin contrasted this with natural selection, which is an explanation for why some animals can mate more readily than others due to their success in dealing with survival factors such as finding food and avoiding predators.
The main point of differentiation between sexual selection and natural selection is that sexual selection can favor the evolution of traits, such as a peacock’s vibrant tail, that would put them at a disadvantage in natural selection (by, say, increasing their risk of predation) (Wright, 2015).
Prior to sociobiology, the idea of sexual selection received little attention in academia.
However, Williams (1966) and Trivers (1972) resurrected the concept as a focus of sociobiology by proposing that the extent that sexual selection happens differently in males and females, producing sex differences in anatomy, physiology, psychology, and behavior, was determined by the extent to which the reproductive efforts of one sex were a limiting resource.
The less invested sex competes for the opportunity to mate with the sex that makes the greater reproductive effort, such as caring for offspring (Wright, 2015).
“Selfish Genes” and Intragenomic Conflict
Finally, the fact that selection can operate differentially on different components of the genome is an area of large amounts of contemporary research.
For example, in species where the Y chromosome can only be transmitted from father to son, such as fruit flies and humans, mutations on the Y chromosome that bias progeny toward producing more reproductive cells with male chromosomes have increased in prevalence over generations, even when they reduce the fitness of those hosting these genes.
Conversely, some qualities, such as mitochondrial DNA, can only be transmitted from mother to daughter, and mutations that bias sexual allocation toward females may proliferate despite potential negative effects on sexual fitness.
This simultaneous selection of different genetic traits that are in antagony with each other is called intragenomic conflict (Wright, 2015).
Recently, scientists have discovered “genomic imprinting,” which is a process where some genes can be activated differently depending on whether they were inherited from one’s mother or father.
This discovery has expanded scientists’ knowledge of potential battlegrounds for intragenomic conflict. For example, genes of paternal origin can be selected to produce fetal and infant traits that aim to reduce the likelihood that the mother may reproduce in the near future (Haig, 2002).
For example, an infant may, as a result of a paternal gene, cry and frequently wean, directing the mother’s efforts away from finding a new mate and toward caring for her young (Wright, 2015).
Daly (2015) argues that these discoveries challenge the sociological views that organisms are strategists that aim to increase the organisms’ “inclusive fitness,” or ability to pass on its genes to the next generation, as selection can and does favor the proliferation of genes that promote their own replication at the expense of the organism’s individual ability to reproduce.
Nonetheless, the individual-level focus of sociobiological research persists (Alcock, 2001; Wright, 2015).
Sociobiology brought a new perspective into research on the evolution of emotion in the 1970s and 1980s, moving the focus of the investigation from basic emotions to the emotions involved in human social interactions (Griffiths, 2001).
Several sociobiologists have made comments that so-called “moral emotions” such as trust, loyalty, guilt, and shame must have evolved as a psychological way to mediate social interactions in an evolutionarily stable way (Weinrich, 1980).
For example, Robert A. Frank suggested that moral emotions evolved as a solution to “commitment problems,” which arise when the winning strategy in an evolutionary interaction involves making a binding commitment to do something against one’s own interests (Frank, 1988).
According to Frank, emotions such as rage and vengefulness evolved as a way to allow organisms to threaten self-destructive aggression in order to deter more powerful aggressors, and emotions such as love and guilt evolved to allow organisms to engage in altruism in situations where there is no retaliation if one partner fails to reciprocate (Griffiths and Gray, 2001).
Altruism in Honey Bees
In insects, the study of social breeding systems has often focused on genes. However, by making what researchers call gene lists, scientists cannot determine how certain traits are related to genes.
Faragalla, Chernyshova, Gallo, and Thompson (2018) created a “gene network” to reveal connections between genes and behavioral traits in honey bees that cannot be revealed by just looking at a gene list. The researchers found that rates of worker sterility could be modeled by gene networks (Faragalla et al., 2018).
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