Altruism and environmental risks to health of parents and their children

This paper tests an equilibrium condition from a model that incorporates: (1) altruism of parents toward their young children, and (2) household production of latent health risks. The model demonstrates that an altruistic parent's marginal rate of substitution between an environmental health risk to herself and to her child is equal to the ratio of marginal risk reduction costs. Econometric estimates support this prediction based on data from a stated preference survey involving 488 parents of children aged 3–12 years. This outcome implies that parents reallocate family resources to at least partly offset the effectiveness of public programs that aim to reduce their children's environmental risks.     

Correlates of pro-sustainability orientation: The affinity towards diversity

The concept of affinity towards diversity (ATD) is introduced and illustrated with two studies on the psychological drivers of pro-sustainability orientation and environmentally friendly behaviors. In light of the importance that biological and social ecological sciences assign to diversity within socio-ecological systems, ATD was conceptualized as an individual predisposition to appreciate the dynamic variety of human–nature interactions in everyday life situations. ATD implies valuing and liking biological and socio-cultural diversity, more than simply being respectful before or accepting differences in the social and physical contexts. Two different samples of Mexicans responded to a series of scales, one of them assessing ATD. The scale exhibited an acceptable level of internal consistency and it also showed construct validity, according to the results of two structural equation models. A first study showed that ATD significantly and negatively covaries with a scale of intolerance, and positively covaries with a measure of environmentally friendly behavior. A second study revealed also that ATD, together with other psychological factors (future orientation, altruism, emotions towards nature), forms the basis for a pro-sustainability orientation which, in turn, predicts environmentally friendly behaviors.     

The independent origin of a queen number bottleneck that promotes cooperation in the African swarm-founding wasp, Polybioides tabidus

When cooperation is based on shared genetic interests, as in most social insect colonies, mechanisms which increase the genetic similarity of group members may help to maintain sociality. Such mechanisms can be especially important in colonies with many queens because within-colony relatedness drops quickly as queen number increases. Using microsatellite markers, we examined the Old World, multiple-queen, swarm-founding wasp Polybioides tabidus which belongs to the ropalidiine tribe, and found that relatedness among the workers was four times higher than what would be expected based on queen number alone. Relatedness was elevated by a pattern of queen production known as cyclical oligogyny, under which, queen number varies, and daughter queens are produced only after the number of old queens has reduced to one or a very few. As a result, the queens are highly related, often as full sisters, elevating relatedness among their progeny, the workers. This pattern of queen production is driven by collective worker control of the sex ratios. Workers are three times more highly related to females than to males in colonies with a single queen while they are more equally related to males and females in colonies with more queens. As a result of this difference, workers will prefer to produce new queens in colonies with a single queen and males in colonies with many queens. Cyclical oligogyny has also evolved independently in another group of swarm-founding wasps, the Neotropical epiponine wasps, suggesting that collective worker control of sex ratios is widespread in polistine wasps. Received: 22 May 2000 / Revised: 24 August 2000 / Accepted: 4 September 2000     

Patch dynamics based on Prisoner's Dilemma game: superiority of golden rule

There has been much literature on ecological model of Prisoner's Dilemma (PD) game. This game illustrates that cooperation can evolve in situations where individuals tend to look after themselves. In order to explain some behaviors of altruism in animal societies, the strategy All Cooperate (AC), often called the Golden Rule, is more appropriate than other strategies. However, very little is known about the superiority of AC. In the present article, we study patch dynamics based on non-iterated PD game, applying two different methods: island and lattice models. Each patch is assumed to be either vacant or composed of a population of AC or All Defect (AD), where AD means a selfish strategy. Both models exhibit a phase transition between a phase where both AC and AD survive, and a phase where AD is extinct. The latter phase means that AC beats AD completely. In the case of lattice model, the extinction of AD easily occurs and the abundance of AC takes a larger value, compared with the island model. Our models can be also extended to general iterated PD game; we describe the reason why AC can outperform any other strategy.     

From eavesdropping on performance to copying the behavior of others: a review of public information use

Public information (PI), a form of indirect social information, is used by individuals to estimate the quality of environmental parameters. It can be acquired in two ways. One way is by noting the performance of others. The other way it can be acquired is by noting the behavioral decisions of other individuals. Performance-based PI has been observed most often in the context of food and breeding patch estimation, as well as by individuals eavesdropping on contests between others in the context of assessing the fighting ability of opponents and the quality of mates. Evidence for the acquisition of PI from behavioral decisions of others comes mostly from studies of copying behavior, although recent work suggests that it also occurs when individuals estimate the tendency of others to be altruistic. PI use appears to be widespread across many taxa, although most work has been conducted on birds and fish. Absent from the literature are clear examples of PI use in mammals. The use of PI appears to often depend on its cost of acquisition and whether it contradicts an individual’s personal prior experience. PI can be an important benefit of associating with others.     

Parental altruism and the value of avoiding acute illness: are kids worth more than parents?

A model describing parents’ preferences to relieve their own and their children's acute illnesses is estimated using stated-preference data. Estimated marginal rates of substitution (MRS) between child and parent illness are about two, indicating that parents value children's illness attributes twice as highly as their own. The MRS is larger for younger children, falls toward unity as the child approaches adulthood, and appears to reflect parental altruism rather than parent–child differences in initial health or illness costs. Intra-family allocations may compensate for chronic health impairments. Parents’ willingness to pay to avoid own or child illness increases with income, declines with fertility, increases at a decreasing rate with duration and number of symptoms, and depends on perceived discomfort and activity restrictions. Current methods of assessing morbidity benefits of environmental regulations may understate substantially the value of children's health, particularly in African-American families.     

Social behaviour in genetically heterogeneous groups of Dictyostelium giganteum

The Dictyostelid or cellular slime moulds (CSMs) are soil amoebae with an asexual life cycle involving social behaviour and division of labour. The most obvious distinction is between ‘germ line’ or pre-spore cells, which survive, and ‘somatic’ or pre-stalk cells, which eventually die. A plausible hypothesis to explain the apparent altruism of pre-stalk cells is that it is directed at clonal relatives. We have tested this hypothesis by comparing indices of altruistic behaviour between clonal and chimeric (genetically heterogeneous) social groups. The groups were generated by mixing amoebae belonging to distinguishable strains of Dictyostelium giganteum. The amoebae of one strain do not aggregate at all when mixed with any of three other strains and aggregate poorly with a fourth. Among the latter, co-aggregation occurs but is followed by varying extents of sorting out. At times, two strains form separate fruiting bodies; in other cases, they remain together but are clustered in clonal groups within a single chimeric structure. Our expectation was that the allocation of cells to the stalk pathway would be higher, and to the spore pathway lower, in clonal social groups than in chimeras. The expectation was not always fulfilled. In addition, three strains could be arrayed in a linear rank order in terms of the relative efficiencies of spore-formation in binary mixtures; but when all three were mixed, they were equally efficient. More than overall genetic similarity, cell fate in a chimera seems to result from complex non-linear interactions based on epigenetic differences.