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Computer experiments that mirror the evolutionary dynamics of sexual and asexual organisms as they occur in nature were used to test features proposed to explain the evolution of sexual recombination. Results show that this evolution is better described as a network of interactions between possible sexual forms, including diploidy, thelytoky, facultative sex, assortation, bisexuality, and division of labor between the sexes, rather than a simple transition from parthenogenesis to sexual recombination. Diploidy was shown to be fundamental for the evolution of sex; bisexual reproduction emerged only among anisogamic diploids with a synergistic division of reproductive labor; and facultative sex was more likely to evolve among haploids practicing assortative mating. Looking at the evolution of sex as a complex system through individual-based simulations explains better the diversity of sexual strategies known to exist in nature, compared to classical analytical models. [ABSTRACT FROM AUTHOR]

W.D. Hamilton's Inclusive Fitness Theory explains the conditions that favor the emergence and maintenance of social cooperation. Today we know that these include direct and indirect benefits an agent obtains by its actions, and through interactions with kin and with genetically unrelated individuals. That is, in addition to kin-selection, assortation or homophily, and social synergies drive the evolution of cooperation. An Extended Inclusive Fitness Theory (EIFT) synthesizes the natural selection forces acting on biological evolution and on human economic interactions by assuming that natural selection driven by inclusive fitness produces agents with utility functions that exploit assortation and synergistic opportunities. This formulation allows to estimate sustainable cost/benefit threshold ratios of cooperation among organisms and/or economic agents, using existent analytical tools, illuminating our understanding of the dynamic nature of society, the evolution of cooperation among kin and non-kin, inter-specific cooperation, co-evolution, symbioses, division of labor and social synergies. EIFT helps to promote an interdisciplinary cross fertilization of the understanding of synergy by, for example, allowing to describe the role for division of labor in the emergence of social synergies, providing an integrated framework for the study of both, biological evolution of social behavior and economic market dynamics. Another example is a bio-economic understanding of the motivations of terrorists, which identifies different forms of terrorism. [ABSTRACT FROM AUTHOR]

Shame has biological roots, possibly enhancing trust, favoring social cohesion. We studied bioeconomic aspects of shame and guilt using three approaches: 1-Anthropo-linguistic studies of Guilt and Shame among the Yanomami, a culturally isolated traditional tribal society; 2-Estimates of the importance different languages assign to the concepts Shame, Guilt, Pain, Embarrassment, Fear and Trust, counting the number of synonyms listed by Google Translate; 3-Quantitative correlations between this linguistic data with socioeconomic indexes. Results showed that Yanomami is unique in having overlapping synonyms for Shame, Fear and Embarrassment. No language had overlapping synonyms for Shame and Guilt. Societies previously described as 'Guilt Societies' have more synonyms for Guilt than for Shame. A large majority of languages, including those from societies previously described as 'Shame Societies', have more words for Shame than for Guilt. The number of synonyms for Guilt and Shame strongly correlated with estimates of corruption, ease of doing business and governance, but not with levels of interpersonal trust. We propose that cultural evolution of shame has continued the work of biological evolution, but its adaptive advantage to society is still unclear. Results suggest that recent cultural evolution must be responsible for the relationship between the levels of corruption of a society and the number of synonyms for Guilt and Shame in its language. This opens a novel window for the study of complex interactions between biological and cultural evolution of cognition and emotions, which might help broaden our insight into bioeconomics. [ABSTRACT FROM AUTHOR]

What are the benefits of society? What are the adaptive advantages of social behavior? The fact that societies exist suggest that society favors synergies in the interactions between individuals. One such synergy or adaptive advantage might be the increased efficiency in the use of scarce resources. This has been postulated to occur in the 'metabolic scaling law', where larger organisms with more cells consume less energy per unit mass than smaller organisms. Here, I develop a similar scale-free index for social synergy applicable to energy consumption, and apply it to social insect colonies and human cities. The results show that all societies studied increase the efficiency of energy consumption with increased sizes. This study shows that social synergy is reliably quantifiable and that its increase with size is much larger in social insects than that observed with the metabolic scaling law in organisms. This allows for the first time to compare quantitatively very different societies, permitting novel studies in social dynamics, for example, the study shows that termite colonies achieve much higher social synergy than ant and honey bee colonies and that Brazilian cities achieve more social synergy than Danish or North American ones, posing new intriguing questions. [ABSTRACT FROM AUTHOR]

Hymenoptera have haploid males, which produce sperm by cloning. Sperm selection theory predicts that because termites have diploid males that produce genetically diverse sperm, they may profit from a high sperm surplus (large K), whereas Hymenoptera (ants, bees and wasps) should produce few sperm per fertilization (low K). Male reproductive ''kings'', which continuously provide spermatozoa during the whole life of the queen, allow for a large K. Available empirical evidence confirms the existence of a large difference in K between diploid insects, especially Blattodea (Isoptera) (K > 1,000), and haplo-diploids such as Hymenoptera (K < 10). The available data suggest that sperm selection may be an important evolutionary force for species with diploid, but not haploid males. [ABSTRACT FROM AUTHOR]

Theoretical and experimental studies suggest that mating and pair formation are not likely to be random. Assortative mating, characterized as “self seeking like”, seems to be widely practiced in nature. Experimental evidence for it is strong among humans seeking a mate. Assortative mating increases the probability of finding a genetically similar mate, without fomenting inbreeding, achieving assortative mating without hindering the working of other mate-selection strategies that aim to maximize the search for “good genes”, optimizing the working of sex in evolutionary terms. Self seeking like seems to be a behavioural inborn trait among humans, and here we present evidence that the same behavioural mechanism seems to be at work when humans choose a pet. We show that in a significant proportion of human-pet pairs, sampled in pet beauty contests, the partners show much higher facial resemblances than can be expected by random pair formation. [ABSTRACT FROM AUTHOR]

The concept of altruism is used in very different forms by computer scientists,economists, philosophers, social scientists, psychologists and biologists. Yet, in order to be useful in social simulations, the concept “altruism” requires a more precise meaning. A quantitative formulation is proposed here, based on the cost/benefit analysis of the altruist and of society at large. This formulation is applied in the analysis of the social dynamic working of behaviors that have been called “altruistic punishments”, using the agent based computer model Sociodynamica. The simulations suggest that “altruistic punishment” on its own cannot maintain altruistic behaviors. “Altruistic behavior” is sustainable in the long term only if these behaviors trigger synergetic forces in society that eventually make them produce benefits to most individuals. The simulations suggest however that “altruistic punishment” may work as a “social investment” , and is thus better called “decentralized social punishment”. This behavior is very efficient in enforcing social norms. The efficiency of decentralized social punishment in enforcing norms was dependent on the type of labor structured of the virtual society. I conclude that what is called “altruistic punishment” emerges as a type of social investment that can evolve either through individual and/or group selection, as a successful device for changing or enforcing norms in a society. Social simulations will help us in better understanding the underlying dynamic working of such devices. [ABSTRACT FROM AUTHOR]

Five candidate pheromone components were identified by analyzing pheromone gland extracts by gas chromatography (GC), coupled GC-electroantennographic detection (EAD), and coupled GC-mass spectrometry (MS): ( E)-11-hexadecenol( E11–16 : OH), ( Z)-11-hexadecenol ( Z11–16 : OH),( E)-11-hexadecenal, ( E)-11-hexadecenyl acetate, and ( Z)-3,( Z)-6,( Z)-9-tricosatriene ( Z3, Z6, Z9–23 : Hy). In electroantennogram (EAG) recordings, synthetic E11–16 : OH elicited stronger antennal responses at low doses than other candidate pheromone components. Field tests demonstrated that synthetic E11–16 : OH as a trap bait was effective in attracting males, whereas addition of Z11–16 : OH inhibited the males' response. Z3, Z6, Z9–23 : Hy strongly enhanced attractiveness of E11–16 : OH, but was not attractive by itself. A pheromone blend with synergistic behavioral activity of an alcohol ( E11–16 : OH) and hydrocarbon ( Z3, Z6, Z9–23 : Hy) component is most unusual in the Lepidoptera. The synthetic two-component pheromone is approximately 60 times more attractive than the female-produced blend and might facilitate the control of this pest. [ABSTRACT FROM AUTHOR]

Advances in multiagent simulation techniques make it possible to study more realistic dynamics of complex systems and allow evolutionary theories to be tested. Here I use simulations to assess the relative importance of reproductive systems (haplodiploidy vs. diploidy), mate selection (assortative mating vs. random mating) and social economics (pay-off matrices of evolutionary games) in the evolutionary dynamics leading to the emergence of social cooperation in the provision of parental care. The simulations confirm that haplo-diploid organisms and organisms mating assortatively have a higher probability for fixing alleles and require less favorable conditions for their fixation, than diploids or organisms mating randomly. The simulations showed that social behavior was most likely to emerge a) when the cost for parental investment was much lower than the benefits to the offspring, b) when cooperation improved synergistically the fitness of offspring compared to the corresponding egoistic behavior and c) when alleles coding for altruistic or social behavior could be rapidly fixed in the population, thanks to mechanisms such as haplo-diploidy and/or assortative mating. Cooperative social behavior always appeared if sociality conferred much higher fitness gains compared to non cooperative alternatives suggesting that the most important factors for the emergence and maintenance of social behavior are those based on energetic or efficiency considerations. The simulations, in congruence with the scant experimental evidence available, suggest that economic considerations rather than genetic ones are critical in explaining the emergence and maintenance of sociality. [ABSTRACT FROM AUTHOR]

Using computer simulations I studied the simultaneous effect of variable environments, mutation rates, ploidy, number of loci subject to evolution and random and assortative mating on various reproductive systems. The simulations showed that mutants for sex and recombination are evolutionarily stable, displacing alleles for monosexuality in diploid populations mating assortatively under variable selection pressure. Assortative mating reduced excessive allelic variance induced by recombination and sex, especially among diploids. Results suggest a novel adaptive value for sex and recombination. They show that the adaptive value of diploidy and that of the segregation of sexes is different to that of sex and recombination. The results suggest that the emergence of sex had to be preceded by the emergence of diploid monosexual organisms and provide an explanation for the emergence and maintenance of sex among diploids and for the scarcity of sex among haploid organisms. [ABSTRACT FROM AUTHOR]

Results of an agent-based computer simulation of the evolution of diploid sexual organisms showed that several mate selection strategies confer much higher average fitness to the simulated populations, and higher evolutionary stability to the alleles coding for these strategies, than random mating. Strategies which select for 'good genes' were very successful, and so were strategies based on assortative mating. The results support the hypothesis that mating is not likely to be random in nature and that the most successful mate selection strategies are those based on assortative mating or on advantageous genes. [ABSTRACT FROM AUTHOR]

Gas chromatography analyses and behavioral assays showed that Atta laevigata, a highly polymorphic ant species, has a mandibular gland secretion that varies with castes. All castes contain 4-methyl-3-heptanone as the main component and its concentration is proportional to head size. Small workers and soldiers, but not medium size workers, also contain 4-methyl-3-heptanol. Queens show variations in their chemical composition after mating, as virgin males contain a secretion dominated by 4-methyl-3-heptanol, and, in a lesser proportion, 4-methyl-3-heptanone. In mated males these proportions are inverted. The compounds 4-methyl-6-hepten-3-one, 4-methyl-4-hepten-3-one, 6-methyl-tetradecene, and 2,6-dimethyl-2-dodecene are found only in queens. The behavioral response elicited by the secretion is mainly alarm, which is elicited more strongly by glands of larger workers. The results suggest that chemical castes, behavioral castes, and morphological castes overlap in this species. [ABSTRACT FROM AUTHOR]

We analyzed the behavioral responses of the ants Camponotus rufipes and Solenopsis geminata towards all instars of Dione junio and Abananote hylonome. We also analyzed ant behavior towards hexane extracts of larvae and extracts of the spines and neck glands of the fifth instars of both species and identified the chemical compounds present. Larvae of both species were repellent to ants from the first instar onward. Later instars survived ant attacks better than earlier instars. The spines and neck glands of the larvae influenced the behavior of C. rufipes. The chemical compounds contained in the hexane extracts of whole first and fifth instars and in the spines and neck glands of fifth instars were principally carboxylic acids and terpenes. Further bioassays confirmed the repellent effect of some of these acids toward ants. [ABSTRACT FROM AUTHOR]

Facultatively sexual entomopathogenic nematodes are a promising model for the experimental study of the adaptive values of sex. Our experiments in the laboratory showed that entomopathogenic nematodes display at least two different strategies in regulating the degree of amphimix as a response to nutritional stress. One strategy promotes the production of males, amphimix and the genetic variability of the offspring, improving the chances for a successful new adaptation. Another strategy increases the production of hermaphrodites at the expense of males, increasing the total number of reproductive individuals and thus the total number of offspring produced. Surprisingly, the strategy used depends upon the strain of symbiotic bacteria the nematodes are growing. The relevance of the results, in helping to discriminate between rival theories for the evolutionary maintenance of sex, is discussed. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented in response to the article on the present government that created the Ministry of Science and Technology that was published in the previous issue.

A letter to the editor in response to the article "Three Cheers for Peers" published in the 2006 issue of "Nature" is presented.