Philosophy Phriday: The Sociobiological Misadventures of Ants

The Daily Ant hosts a weekly series, Philosophy Phridays, in which real philosophers share their thoughts at the intersection of ants and philosophy. This is the forty-eighth contribution in the series, submitted by Dr. Jay Odenbaugh.


The Sociobiological Misadventures of Ants

In the 1960s, Richard Levins, Richard Lewontin, Robert MacArthur, E. O.Wilson, and Leigh Van Valen occasionally met in Marlboro, Vermont to discuss how “simple theory” could integrate population genetics, ecology, biogeography, and ethology (Wilson, 2006; Singh, 2001). At this time, evolutionary biology and ecology were being attacked on two fronts. On the one, there was the rise of molecular biology which looked like it would replace organismal biology (however see Hubby and Lewontin (1966); Lewontin and Hubby (1966)). On the other, there was the rise of systems ecology with its FORTRAN computers and “big data.” Richard Levins argued that this sort of modeling confused “numbers with knowledge” (Levins, 1968, 504). In response, mathematical population biology took off (Levins, 1968; Lewontin, 1974; MacArthur and Wilson, 1967). However, there was one area which had not been added: ethology, the science of animal behavior. Wilson would controversially create sociobiology as the integration of ethology and population biology. Ants would be at the center of this story, and it begins in three strands (Wilson, 2006).

First, in 1953, E. O.Wilson heard a pair of lectures at Harvard University by the great ethologists Niko Tinbergen and Konrad Lorenz. From these lectures, Wilson became enamored at the idea of a fixed action pattern. Wilson’s conviction was that the concept could be applied to ants – not through sights and sounds but through “pheromones.” A few years later, Wilson constructed an artificial nest of Plexiglas for watching an ant colony of the genus Solenopsis (“fire ants”).

Wilson3Figure 1: E. O. Wilson studies fire ants in the insectary at Harvard University, September 8, 1975

He knew that scout ants left chemical trails from their abdomen in order to direct workers to food. However, he didn’t know the chemical or organ of secretion. After painstaking microscopic work and experiments of “squishing” tiny organs, he realized the organ was Dufour’s gland. Next, he needed large numbers of ants, which led Wilson and his co -workers to Florida. There, they pushed large mounds into creeks. The ants form a floating mass protecting the queen and thus they could sample as many as they wanted. After chemical analysis, they determined the pheromone to be farnesene, a terpenoid. This work coupled with the theoretical analysis of William Bossert led to some of Wilson’s most signficant and lasting contributions on pheromones and animal communication (Bossert and Wilson, 1963; Wilson and Bossert, 1963).

After this pioneering work, Wilson became restless with his study of pheromones and island biogeography respectively. He hosted the entomologist Bert Hölldobler at Harvard, which began a period of intense colloboration. Hölldobler came from Germany and the ethological tradition of Lorenz, Tinbergen, and von Frisch whereas Wilson came from that of population biology. Both thought the two should be brought together. Together they did serious and intense research on the genus Prionopelta, studying colony size, the number of queens, division of labor, and the types of animals captured by the workers. This culminated in papers and ultimately in their monumental Pulitzer Prize-winning book, The Ants (1990). Wilson thus keenly understood ants as a social insect.

In 1955, Wilson was approached by Stuart Altmann to be his dissertation advisor. Altmann wanted to study the social behavior of rhesus monkeys in Cayo Santiago, which was outside of Wilson’s expertise. They lived with the monkeys for two days, spurring Wilson to think about a unified account of social behavior. Rhesus and ants are so different, could a theory be formulated for both? Wilson realized his most obvious point of contribution was the study of the division of labor in social insects. In the fifties, he had begun to study “adaptive demography,” combining allometry and the division of labor. Small changes in anatomy can change the role an ant plays in a colony (Wilson, 1968; Wilson et al., 1985). His work on the evolution of castes in social insects came to fruition with mathematician George Oster (Oster and Wilson, 1978).

By the 1970s, E. O. Wilson was captivated by this vision of an integrated “sociobiology” (Figure 2).

Figure 2: Sociobiology and its connections to population biology and ethology (Wilson, 1975, 4, 5)

On a train ride to Miami in the spring of 1965, Wilson read William D. Hamilton’s (1964a; 1964b) pair of papers on his theory of kin selection. Though skeptical at the beginning of his travels, by the time he passed through Virginia he was convinced it was right in its explanation of eusociality; his own“paradigm shift.” The primary problem of sociobiology is altruism. If an organism provides a benefit to another organism at a cost to themselves, then how could this altruistic trait evolve by natural selection when the free rider receives the benefit at no cost? Hamilton’s rule is the beautiful core for his proposed solution to the problem of altruism.

rb > c

Here r, the coefficient of relatedness, is a measure of the probability that individuals share an allele by common descent, b is benefit and c is cost to reproductive fitness. For identical twins r is 1.0, for full-siblings it is 0.5, for half-siblings it is 0.25, for cousins it is 0.125, etc. This rule says if the benefit discounted by the relatedness of the actor and recipient is greater than the cost to the actor, altruism can evolve. Hamilton’s rule implies the lower r, then greater the benefits relative to costs must be.

Hamilton thought that kin selection was crucial for explaining the evolution of eusociality in ants. Eusocial insects have cooperative care, sterile castes, and overlapping generations. For example, sisters forgo having their own offspring by helping the queen have more. Many species in the order Hymenoptera, including ants, have a special mode of sex determination, haplodiploidy. Males develop from unfertilized eggs and are thus haploid. Females develop from fertilized eggs and thus are diploid. This implies that for two sisters r = 0.75; for daughter to motherr = 0.5; for son to mother r = 0.5; for brother to brother r = 0.5; for brother to sister r = 0.25. Thus, in a haplodiploid species, if a queen mates only once, then females may have higher fitness by helping their mother produce more sisters than producing their own daughters. Haplodiploidy through kin selection provides a possible explanation of the evolution of a worker caste that helps their mother (for complications see Queller and Strassmann (1998); Nowak et al. (2010); Abbot et al. (2011)).

In the New York Review of Books November 1975, Wilson’s Sociobiology was severely criticized by his Harvard colleagues Richard Lewontin and Stephen JayGould along with others from Science for the People. They claimed determinist theories like Wilson’s provide a “genetic justification” of the status quo, sterilization laws, and Nazi Eugenics. One criticism was that Wilson abused biological metaphors or analogies.

One subtle way in which Wilson attempts to link animals and humans is to use metaphors from human societies to describe characteristics of animal societies. For instance, in insect populations, Wilson applies the traditional metaphors of “slavery” and “caste,” “specialists” and“generalists” in order to establish a descriptive framework. Thus, he promotes the analogy between human and animal societies and leads one to believe that behavior patterns in the two have the same basis. Also, institutions such as slavery are made to seem natural in human societies because of their “universal” existence in the biological kingdom. But metaphor and presumed analogy cannot be allowed to mask the absence of evidence.

One important example is Wilson’s use of ants and the evolution of eusociality in his explanation of homosexuality (Wilson, 1975, 311, 343). But his fullest discussion occurs in On Human Nature.

How can genes predisposing their carriers toward homosexuality spread through the population if homosexuals have no children? One answer is that their close relatives could have had more children as a result of their presence. The homosexual members of primitive societies could have helped members of the same sex, either while hunting and gathering or in more domestic occupations at the dwelling sites. Freed from the special obligations of parental duties, they would have been in a position to operate with special efficiency in assisting close relatives. They might further have taken the roles of seers, shamans, artists, and keepers of tribal knowledge. If the relatives – sisters, brothers, nieces, nephews, and others – were benefitted by higher survival and reproduction rates, the genes the individuals shared with the homosexual specialists would have increased at the expense of alternative genes. Inevitably, some of these genes would have been those that predisposed individuals toward homosexuality. (Wilson, 1978, 144-5)

Wilson’s kin selection hypothesis has been seriously criticized (Kitcher, 1985; Futuyma and Risch, 1984). First, the only evidence Wilson supplies are twin studies claiming homosexuality is heritable. But, showing a trait is heritable doesn’t show it exhibits heritable variation in fitness; i.e. it evolved by natural selection. Second, sterile workers’ aid in ants is a facultative trait with no heritability. A queen and workers differ by developmental history, not by genes. Wilson proposes heterosexuals and homosexuals differ genetically. Third, at best this explains why certain members should forgo having their own offspring and helping relatives. It doesn’t explain why they would be homosexual as opposed to heterosexual helpers.

Wilson would later claim he was a “political näif”; he didn’t expect the Marxist critique from colleagues. Regardless, for Wilson, sociobiology was an outgrowth of the attempt to integrate population biology and ethology quantitatively. It was also a remarkably controversial mix of of science, politics, and ants (Segestråle, 2000).

References

Abbot, P., J.Abe, J. Alcock, S. Alizon, J.A. Alpedrinha, M. Andersson, J.-B. Andre,M. Van Baalen, F. Balloux, S. Balshine, et al. (2011). Inclusive fitness theoryand eusociality. Nature 471(7339), E1–E4.

Bossert, W. H. and E. O. Wilson (1963). The analysis of olfactory communicationamong animals. Journal of theoretical biology 5(3), 443–469.

Futuyma, D. J. and S. J. Risch (1984). Sexual orientation, sociobiology, and evolution.Journal of Homosexuality 9(2-3), 157–168.

 

Hamilton, W. D. (1964a). The genetical evolution of social behaviour. ii. Journal of theoretical biology 7(1), 1–16.

Hamilton, W. D. (1964b). The genetical evolution of social behaviour. ii. Journalof theoretical biology 7(1), 17–52.

Hölldobler, B. and E. O. Wilson (1990). The ants. Harvard University Press.

Hubby, J. L. and R. C. Lewontin (1966). A molecular approach to the study of genic heterozygosity in natural populations. i. the number of alleles at different loci in drosophila pseudoobscura. Genetics 54(2), 577.

Kitcher, P. (1985). Vaulting ambition: sociobiology and the quest for human nature. MIT Press.

Levins, R. (1968). Evolution in changing environments: some theoretical explorations. Princeton University Press.

Lewontin, R. C. (1974). The genetic basis of evolutionary change, Volume 560. Columbia University Press New York.

Lewontin, R. C. and J. L. Hubby (1966). A molecular approach to the study of genic heterozygosity in natural populations. ii. amount of variation and degree of heterozygosity in natural populations of drosophila pseudoobscura. Genetics 54(2), 595.

MacArthur, R. H. and E. O. Wilson (1967). The theory of island biogeography. Princeton university press.

Nowak, M. A., C. E. Tarnita, and E. O.Wilson (2010). The evolution of eusociality. Nature 466(7310), 1057–1062.

Oster, G. F. and E. O. Wilson (1978). Caste and ecology in the social insects. Princeton University Press.

Queller, D. C. and J. E. Strassmann (1998). Kin selection and social insects. Bioscience 48(3), 165–175.

Segestråle, U. (2000). Defenders of the truth: the sociobiology debate. Oxford University Press.

Singh, R. S. (2001). Thinking about evolution: historical, philosophical, and political perspectives, Volume 2. Cambridge University Press.

Wilson, E. O. (1968). The ergonomics of caste in the social insects. The American Naturalist 102(923), 41–66.

Wilson, E. O. (1975). Sociobiology: The New Synthesis. Harvard University Press.

Wilson, E. O. (1978). On Human Nature. Harvard University Press.

Wilson, E. O. (2006). Naturalist. Island Press.

Wilson, E. O. et al. (1985). The sociogenesis of insect colonies. Science 228(4707), 1489–1495.

Wilson, E. O. and W. H. Bossert (1963). Chemical communication among animals. Recent progress in hormone research 19, 673.


DSC_0527Dr. Jay Odenbaugh is an Associate Professor in the Department of Philosophy at Lewis & Clark College. His main areas of research interest are in the philosophy and history of science (especially biology and psychology) though he has strong interests in aesthetics and ethics. In the history of philosophy, Dr. Odenbaugh is especially fascinated by the American pragmatists and their descendants. His research has tended to focus on foundational issues related to the  sciences especially in evolutionary biology and ecology. Currently, he is finishing a book manuscript In a Sentimental MoodEmotion, Evolution, and Expression, an interdisciplinary exploration of what psychology, behavioral ecology, and evolutionary biology have to say about our emotions and their expression. This spring, Dr. Odenbaugh is writing a short book entitled Ecological Models for Cambridge University Press.

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