Sober &; Wilson’s evolutionary arguments for psychological altruism: a reassessment

In their book Unto Others, Sober and Wilson argue that various evolutionary considerations (based on the logic of natural selection) lend support to the truth of psychological altruism. However, recently, Stephen Stich has raised a number of challenges to their reasoning: in particular, he claims that three out of the four evolutionary arguments they give are internally unconvincing, and that the one that is initially plausible fails to take into account recent findings from cognitive science and thus leaves open a number of egoistic responses. These challenges make it necessary to reassess the plausibility of Sober & Wilson’s evolutionary account—which is what I aim to do in this paper. In particular, I try to show that, as a matter of fact, Sober & Wilson’s case remains compelling, as some of Stich’s concerns rest on a confusion, and those that do not are not sufficiently strong to establish all the conclusions he is after. The upshot is that no reason has been given to abandon the view that evolutionary theory has advanced the debate surrounding psychological altruism.     

Perspectives and Parameterizations Commentary on Benjamin Kerr and Peter Godfrey-Smith's ``Individualist and Multi-Level Perspectives on Selection in Structured Populations'

We have two main objections to Kerr and Godfrey-Smith's (2002) meticulous analysis. First, they misunderstand the position we took in Unto Others – we do not claim that individual-level statements about the evolution of altruism are always unexplanatory and always fail to capture causal relationships. Second, Kerr and Godfrey-Smith characterize the individual and the multi-level perspectives in terms of different sets of parameters. In particular, they do not allow the multi-level perspective to use the individual fitness parameters _i and _i. We don't see why the multi-level perspective prevents one from thinking in these terms. Kerr and Godfrey-Smith's argument that Uyenoyama and Feldman's (1980, 1992) definition of altruism belongs more to the individualist perspective than it does to the multi-level perspective is an artifact of their choice of parameters; the same point applies to their argument about the individualism inherent in the idea of Class I and Class II fitness structures.     

Familial selection and the evolution of social behaviour re-examined

The equation for the fitness requirements for the evolution of altruism by diploid workers in haplodiploid species was derived from the model. of Scudo & Ghiselin (1975). When the benefit to a family is proportional to the number of altruists, the constraints on fitness were found to be the same as for haploid altruists in haplodiploid species and for workers of ether sex in diploid species, in contrast to the equation given by Scudo & Ghiselin (1975). With this correction, their results are now in agreement both with comparable allele frequency models and with kin selection games theory. The general condition for evolution of altruism under this model, when benefits are not necessarily proportional to the number of altruists, was also derived. The result appears to differ from games theory predictions, but this is solely because the basic assumptions are not comparable. Altruism is less likely to arise under these conditions, which are less favorable for altruism at gene frequencies above 0·33.     

The Significance of Non-vertical Transmission of Phenotype for the Evolution of Altruism

My aim in this paper is to demonstrate that a very simple learning rule based on imitation can help to sustain altruism as a culturally transmitted pattern or behaviour among agents playing a standard prisoner’s dilemma game. The point of this demonstration is not to prove that imitation is single-handedly responsible for existing levels of altruism (a thesis that is false), nor is the point to show that imitation is an important factor in explanations for the evolution of altruism (a thesis already prominent in the existing literature). The point is to show that imitation contributes to the evolution of altruism in a particular way that is not always fairly represented by evolutionary game theory models. Specifically, the paper uses a simple model to illustrate that cultural transmission includes mechanisms that do not transmit phenotype vertically (i.e. from parent to related offspring) and that these mechanisms can promote altruism in the absence of any direct biological propensity favouring such behaviour. This is a noteworthy result because it shows that evolutionary models can be built to explicitly reflect the contribution of non-vertical transmission in our explanations for the evolution of altruism among humans and other social species.     

Testing kin altruism in long-tailed macaques (Macaca fascicularis) in a food-sharing experiment

Social grooming and coalition formation have been main foci in studies concerning altruism in monkeys. Results have been inconclusive because the altruistic nature of these behaviors remains unclear. I investigated altruism in a more transparent context via an apparatus in which captive long-tailed macaque females had the choice to exploit a food source themselves or to yield the food to a test partner. I hypothesized that if potential donors behaved altruistically toward kin, they would yield the food sources longer to kin than to nonkin. Of 11 tested potential donors, 8 did not discriminate between daughters or sisters and nonkin. Thus, the experiments do not support the kin altruism hypothesis. Three females let their youngest offspring have more food than matched juvenile nonrelatives. Behavioral observations strongly suggested,however, that it was primarily spiteful behavior toward juvenile nonrelatives that caused the differences between kin and nonkin in these three cases.     

Altruism and organism: disentangling the themes of multilevel selection theory

The evolution of groups into adaptive units, similar to single organisms in the coordination of their parts, is one major theme of multilevel selection theory. Another major theme is the evolution of altruistic behaviors that benefit others at the expense of self. These themes are often assumed to be strongly linked, such that altruism is required for group-level adaptation. Multilevel selection theory reveals a more complex relationship between the themes of altruism and organism. Adaptation at every level of the biological hierarchy requires a corresponding process of natural selection, which includes the fundamental ingredients of phenotypic variation, heritability, and fitness consequences. These ingredients can exist for many kinds of groups and do not require the extreme genetic variation among groups that is usually associated with the evolution of altruism. Thus, it is reasonable to expect higher-level units to evolve into adaptive units with respect to specific traits, even when their members are not genealogically related and do not behave in ways that are obviously altruistic. As one example, the concept of a group mind, which has been well documented in the social insects, may be applicable to other species.     

Selective pressures for accurate altruism targeting: evidence from digital evolution for difficult-to-test aspects of inclusive fitness theory

Inclusive fitness theory predicts that natural selection will favour altruist genes that are more accurate in targeting altruism only to copies of themselves. In this paper, we provide evidence from digital evolution in support of this prediction by competing multiple altruist-targeting mechanisms that vary in their accuracy in determining whether a potential target for altruism carries a copy of the altruist gene. We compete altruism-targeting mechanisms based on (i) kinship (kin targeting), (ii) genetic similarity at a level greater than that expected of kin (similarity targeting), and (iii) perfect knowledge of the presence of an altruist gene (green beard targeting). Natural selection always favoured the most accurate targeting mechanism available. Our investigations also revealed that evolution did not increase the altruism level when all green beard altruists used the same phenotypic marker. The green beard altruism levels stably increased only when mutations that changed the altruism level also changed the marker (e.g. beard colour), such that beard colour reliably indicated the altruism level. For kin- and similarity-targeting mechanisms, we found that evolution was able to stably adjust altruism levels. Our results confirm that natural selection favours altruist genes that are increasingly accurate in targeting altruism to only their copies. Our work also emphasizes that the concept of targeting accuracy must include both the presence of an altruist gene and the level of altruism it produces.     

Evolutionary relationship of the Bacillus licheniformis macrolide-lincosamide-streptogramin B resistance elements

Summary Naturally occurring erythromycin (Em) resistance was found in 11 of the 18 Bacillus licheniformis isolates tested but was absent from a wide variety of other Bacillus strains. The Em resistance elements confer inducible macrolide-lincosamide-streptogramin B (MLS) resistance and are related to ermD an MLS resistance element previously cloned from the chromosome of B. licheniformis 749. The MLS sensitive B. licheniformis strains and the other sensitive Bacillus strains tested, lack sequences with detectable homology to ermD. The sensitive B. licheniformis strains do exhibit homology to sequences which flank ermD in B. licheniformis 749. The relative sizes of the homologous DNA fragments suggest that the sensitive strains are lacking a 3.6 kb segment which contains ermD. It is shown that ermD is homologous to chromosomal DNA from Streptomyces erythreus ATCC 11635, an Em producing organism. These observations suggest to us that MLS resistance may have arisen in the Streptomyces and spread to B. licheniformis another gram positive bacterium found in soil. It is further proposed that ermD is or was located on a transposon-like element and has spread and evolved further to yeild a variety of related Staphylococcal and Streptococcal MLS determinants.     

Classification, Convention and Logic

An attempt has been made to establish axiomatically the principles of biological classification. It is shown that if phylogenetic classification is based on the notion of dichotomous origin of new taxa implied in Hennig's theory of cladism then the outcome must be a hierarchy in the form of a dichotomous dendrogram. Since the rules of traditional classification do not lead to this type of "phylogenetic tree" it is concluded that the conventions of ordinary systematics do not permit the erection of a "natural system".     

More on the genetical theory of multilevel selection

In my article The genetical theory of multilevel selection, I provided a synthesis of the theory of multilevel selection (MLS) and the theory of natural selection in class‐structured populations. I framed this synthesis within Fisher's genetical paradigm, taking a strictly genetical approach to traits and fitness. I showed that this resolves a number of long‐standing conceptual problems that have plagued the MLS literature, including the issues of ‘aggregate’ vs. ‘emergent’ group traits, ‘collective fitness₁’ vs. ‘collective fitness₂’ and ‘MLS1’ vs. ‘MLS2 ‘. In his commentary, Goodnight suggests this theoretical and conceptual synthesis is flawed in several respects. Here, I show this is incorrect, by: reiterating the theoretical and conceptual goals of my synthesis; clarifying that my genetical approach to traits is necessary for a proper analysis of the action of MLS independently of non‐Darwinian factors; emphasizing that the Price–Hamilton approach to MLS provides a consistent, useful and conceptually superior theoretical framework; and explaining the role of reproductive value in the study of natural selection in class‐structured populations. I also show that Goodnight's contextual analysis treatment of MLS in a class‐structured population is mathematically, biologically and conceptually inadequate.     

Role of male dispersal in the evolution of female altruistic behavior in viscous populations

A computer simulation was conducted to examine the effect of differential dispersal of sexes on the evolution of altruism in viscous populations. First, a basic model, which was regarded as a purely viscous population model, was constructed. The model was assumed to be the same as the simulation model of Wilson etal. (1992), except that it assumed sexual reproduction and that only females show altruistic behavior toward females. For the basic model, altruism could not evolve when b/Nc, where b is the benefit of the altruism to the recipient, c is the cost to the altruist, and N is the number of interacting neighbors. The male dispersal model I assumed that females disperse to nine neighboring sites including the natal site, but males disperse to eight sites farther than females do. For this model, altruistic alleles could evolve when b/N was equal to c or b/N was slightly smaller than c only when the male dispersal distance was slightly larger than those of females. The male dispersal model II assumed that the male dispersal distance follows a normal probability distribution. The Vole model was based on actual data of the gray-sided vole, Clethironomys rufocanus bedfordiae, whose frequency distribution of dispersal distance was similar to a normal distribution. For these models, altruism could evolve under the condition that b/N was slightly smaller than c when the dispersal distances of males were larger than those of females. The results indicate that the differential dispersal of sexes, in which females are philopatric and males disperse farther than females, can somewhat increase the probability of spreading altruistic alleles in viscous populations.     

Origins of altruism diversity I: the diverse ecological roles of altruistic strategies and their evolutionary responses to local competition

Nature abounds with a rich variety of altruistic strategies, including public resource enhancement, resource provisioning, communal foraging, alarm calling, and nest defense. Yet, despite their vastly different ecological roles, current theory typically treats diverse altruistic traits as being favored under the same general conditions. Here, we introduce greater ecological realism into social evolution theory and find evidence of at least four distinct modes of altruism. Contrary to existing theory, we find that altruistic traits contributing to "resource-enhancement" (e.g., siderophore production, provisioning, agriculture) and "resource-efficiency" (e.g., pack hunting, communication) are most strongly favored when there is strong local competition. These resource-based modes of helping are "K-strategies" that increase a social group's growth yield, and should characterize species with scarce resources and/or high local crowding caused by low mortality, high fecundity, and/or mortality occurring late in the process of resource-acquisition. The opposite conditions, namely weak local competition (abundant resource, low crowding), favor survival (e.g., nest defense) and fecundity (e.g., nurse workers) altruism, which are "r-strategies" that increase a social group's growth rate. We find that survival altruism is uniquely favored by a novel evolutionary force that we call "sunk cost selection." Sunk cost selection favors helping that prevents resources from being wasted on individuals destined to die before reproduction. Our results contribute to explaining the observed natural diversity of altruistic strategies, reveal the necessary connection between the evolution and the ecology of sociality, and correct the widespread but inaccurate view that local competition uniformly impedes the evolution of altruism.     

Kin-selection,reciprocal altruism,and information sharing among Maine lobstermen

In this paper, the sharing of information about the location of lobsters among lobstermen in two Maine harbors is described. First, why the sharing of such information is likely to entail an economic loss for the transmitters is explained. Then, the extent to which the principles of kin-selection and reciprocal altruism can account for the sharing of information is determined. Many cases of information sharing in one of the harbors do not appear to be the type of kin-directed or reciprocal acts expected to be produced by kin-selection or reciprocal altruism as they are usually conceived. The behavior of these lobstermen may be the result of the advantages of maintaining a complex web of social relationships among them. Failure to appreciate the complexity of such relationships in some fishing communities is suggested to be a major shortcoming in the economic models previously used to explain information management among commercial fishermen. I conclude that a more complex model of reciprocal altruism is needed to account for the information sharing among this group of Maine lobstermen, and perhaps many other human social groups.     

Natural selection of altruism in inelastic viscous homogeneous populations

Biological explanations are given of three main uninterpreted theoretical results on the selection of altruism in inelastic viscous homogeneous populations, namely that non-overlapping generations hinder the evolution of altruism, fecundity effects are more conducive to altruism than survival effects, and one demographic regime (so-called death-birth) permits altruism whereas another (so-called birth-death) does not. The central idea is ‘circles of compensation’, which measure how far the effects of density dependence extend from a focal individual. Relatednesses can then be calculated that compensate for density dependence. There is very generally a ‘balancing circle of compensation’, at which the viscosity of the population slows up selection of altruism, but does not affect its direction, and this holds for altruism towards any individual, not just immediate neighbours. These explanations are possible because of recent advances in the theory of inclusive fitness on graphs. The assumption of node bitransitivity in that recent theory is relaxed to node transitivity and symmetry of the dispersal matrix, and new formulae show how to calculate relatedness from dispersal and vice versa.     

Accidental altruism in insular pit-vipers (Gloydius shedaoensis, Viperidae)

Darwinian theory predicts that organisms will display traits that benefit themselves rather than other individuals; exceptions to this rule usually are explicable by kin selection. Our studies on an insular population of venomous snakes in north-eastern China reveal a different situation. Only one species of snake (Gloydius shedaoensis, Viperidae) occurs on the island of Shedao, and displays altruism between size (age) classes. First, small snakes frequently kill prey items larger than they can swallow themselves. This behaviour enhances rates of feeding of larger conspecifics, which scavenge the birds' carcasses. Second, large snakes kill raptorial birds (sparrowhawks Accipiter nisus) that pose little or no threat to themselves. This behaviour reduces predation risk for smaller snakes. These effects are presumably accidental consequences of the high venom toxicity of the pit-vipers, which enable them to kill inedible prey and non-threatening predators at little cost. Nonetheless, this accidental altruism may have significant ecological consequences. For example, these behaviours may contribute to the remarkably high population densities of snakes on Shedao.     

Bioaltruism reconsidered

Altruistic behavior is often regarded as sociobiology's most central theoretical problem, but is it? Altruism in biology, bioaltruism, has many meanings, which can be grouped into two categories. The first I will callcommon bioaltruism. It is primarily of ethological relevance. The second,evolutionary bioaltruism, is a special category in evolutionary respects in that it may indeed pose a problem for evolutionary theory. These categories are logically independent. Moreover, both of them are logically different from altruism in its everyday psychological or moral sense. Sociobiological examples of bioaltruistic behavior concern bioaltruism in the first sense only, so the theoretical problem ‘altruism’ is supposed to pose, is indeed nothing but a theoretical problem and the bioaltruism that actually occurs has no evolutionary relevance. Nevertheless, evolutionary theory is relevant to our understanding of the possibility of common bioaltruism, and that possibility — even though bioaltruism is conceptually different from ethical altruism — is relevant for ethicists: it sheds light on what we can ask people to do or not to do.     

MULTILAYERED STRUCTURES (MLSs) IN TWO DINOFLAGELLATES,KATODINIUM CAMPYLOPS AND WOLOSZYNSKIA PASCHERI1

The multilayered structure (MLS), best-known from the flagellar apparatus of charophycean green algae and land plant motile cells, is reported for the first time in members of the Dinophyceae. The MLSs in two dinoflagellates, Katodinium campylops (Harris) Fott and Woloszynskia pascheri (Suchlandt) von Stosch, are similar to other MLSs in possessing the microtubular spline and lamellar strip. Also, as in the majority of MLS-containing organisms, 1) the MLS of each dinoflagellate is closely associated with basal bodies; 2) the spline microtubules possess “keel-like” extensions and 3) extend beyond the MLS, forming a microtubular rootlet that runs beneath the cell surface in a posterior direction; and 4) a mitochondrion is associated with the MLS (K. campylops only) The size, location, and general construction of the MLSs of K. campylops and W. pascheri suggest that they may be homologous to previously described MLSs.     

Psychological and Evolutionary Evidence for Altruism

Sober and Wilson have recentlyclaimed that evolutionary theory can do whatneither philosophy nor experimental psychologyhave been able to, namely, ``break the deadlock'in the egoism vs. altruism debate with anargument based on the reliability of altruisticmotivation. I analyze both their reliabilityargument and the experimental evidence ofsocial psychology in favor of altruism in termsof the folk-psychological ``laws' and inferencepatterns underlying them, and conclude thatthey both rely on the same patterns. I exposethe confusions that have led Sober and Wilsonto defend a reliability argument whilerejecting the experimental evidence of socialpsychology.     

Can natural selection favour altruism between species?

Darwin suggested that the discovery of altruism between species would annihilate his theory of natural selection. However, it has not been formally shown whether between‐species altruism can evolve by natural selection, or why this could never happen. Here, we develop a spatial population genetic model of two interacting species, showing that indiscriminate between species helping can be favoured by natural selection. We then ask if this helping behaviour constitutes altruism between species, using a linear‐regression analysis to separate the total action of natural selection into its direct and indirect (kin selected) components. We show that our model can be interpreted in two ways, as either altruism within species, or altruism between species. This ambiguity arises depending on whether or not we treat genes in the other species as predictors of an individual's fitness, which is equivalent to treating these individuals as agents (actors or recipients). Our formal analysis, which focuses upon evolutionary dynamics rather than agents and their agendas, cannot resolve which is the better approach. Nonetheless, because a within‐species altruism interpretation is always possible, our analysis supports Darwin's suggestion that natural selection does not favour traits that provide benefits exclusively to individuals of other species.     

Prosocial values and group assortation

Ninety-five freshmen each recruited three peers to play a "group bidding game," an N-person prisoner’s dilemma in which anyone could win movie tickets depending on their scores in the game. Prior to playing, all participants completed a measure of prosocial value orientation. Replicating and extending earlier findings (Sheldon and McGregor 2000), our results show that prosocial participants were at a disadvantage within groups. Despite this vulnerability, prosocial participants did no worse overall than asocial participants because a counteracting group-level advantage arose for prosocials, who tended to be concentrated in groups. Implications of this assortative process for the egoism/altruism debate, and for hierarchical selection theory, are discussed.