Does a tag system effectively support emerging cooperation?

This paper investigates whether the so-called Tag Systems support emerging cooperation with respect to 2x2 games. The Tag System, initially proposed by Riolo et al. [2001. Evolution of cooperation without reciprocity. Nature 414, 441-443], gives each agent both a Tag and Tol defined by [0,1] real numbers. Tol is a tolerance for recognizing an opponent as a company. Both Tag and Tol are assumed to be evolving. Results show that the tag's effectiveness depends on whether the AllD strategy is allowed in the system. Allowing AllD implies that green beard effect does not work in the system. Thus, (1) the tag's effectiveness is more meager than that reported by Riolo et al., (2) the Tag System can use alternating reciprocity more effectively than the analytic solution in a Hero game; (3) a system using a 2D tag space supports cooperation more effectively than the usual Tag System.     

Constraints on the origin and maintenance of genetic kin recognition

Kin-recognition mechanisms allow helping behaviors to be directed preferentially toward related individuals, and could be expected to evolve in many cases. However, genetic kin recognition requires a genetic polymorphism on which recognition is based, and kin discriminating behaviors will affect the evolution of such polymorphism. It is unclear whether genetic polymorphisms used in kin recognition should be maintained by extrinsic selection pressures or not, as opposite conclusions have been reached by analytical one-locus models and simulations exploring different population structures. We analyze a two-locus model in a spatially subdivided population following the island model of dispersal between demes of finite size. We find that in the absence of mutation, selection eliminates polymorphism in most cases, except with extreme spatial structure and low recombination. With mutation, the population may reach a stable limit cycle over which both loci are polymorphic; however, the average frequency of conditional helping can be high only under strong structure and low recombination. Finally, we review evidence for extrinsic selection maintaining polymorphism on which kin recognition is based.     

Does kin structure explain the occurrence of workers in a lower termite?

Kinship plays a fundamental role in the origin of social life. It is also predicted to affect numerous details within animal societies, yet recent studies revealed equivocal results. We tested the influence of relatedness for the occurrence of workers in the termite Cryptotermes secundus. Here individuals are developmentally flexible to remain workers or to become dispersing sexuals that found new colonies. Furthermore, colony relatedness naturally increases with inbreeding and decreases when neighboring colonies fuse. Similar to recent studies on social Hymenoptera, our experimental change in relatedness gave equivocal results. Reducing relatedness within colonies did not have an effect, but individuals in inbred colonies were less likely to disperse and more likely to remain workers as predicted by kinship arguments. Several explanations for the interpretation of these equivocal results are provided.     

Coveting thy neighbors fitness as a means to resolve social dilemmas

In spatial evolutionary games the fitness of each individual is traditionally determined by the payoffs it obtains upon playing the game with its neighbors. Since defection yields the highest individual benefits, the outlook for cooperators is gloomy. While network reciprocity promotes collaborative efforts, chances of averting the impending social decline are slim if the temptation to defect is strong. It is, therefore, of interest to identify viable mechanisms that provide additional support for the evolution of cooperation. Inspired by the fact that the environment may be just as important as inheritance for individual development, we introduce a simple switch that allows a player to either keep its original payoff or use the average payoff of all its neighbors. Depending on which payoff is higher, the influence of either option can be tuned by means of a single parameter. We show that, in general, taking into account the environment promotes cooperation. Yet coveting the fitness of one's neighbors too strongly is not optimal. In fact, cooperation thrives best only if the influence of payoffs obtained in the traditional way is equal to that of the average payoff of the neighborhood. We present results for the prisoner's dilemma and the snowdrift game, for different levels of uncertainty governing the strategy adoption process, and for different neighborhood sizes. Our approach outlines a viable route to increased levels of cooperative behavior in structured populations, but one that requires a thoughtful implementation.     

在我国失效的美国心血管疾病治疗药物的PCT 专利申请数据挖掘

目的：从没有在中国得到保护的美国专利申请或专利中寻找心血管疾病治疗药物研发的思路。方法：对申请日从2005 年1 月1 日至2014 年12 月31 日的美国心血管系统疾病治疗药物PCT 申请进入中国国家阶段后失效的专利申请及专利数据进行整序和分析,依据其在美国本土的法律状态确定其技术含金量。结果：未得到中国专利保护的美国心血管系统疾病治疗药物PCT 申请共174 件,其中170 件申请了美国优先权或进入了美国国家阶段。结论：170 件美国心血管系统疾病治疗药物PCT 申请在美国申请优先权,大多数因美国的优先权临时申请过期而放弃。14 件在美国本土的优先权申请失效,其所含信息量应该相当于公开发表的论文的信息量,23 件在美国本土优先权授权的专利技术具有一定的技术含金量,目前在中国已经进入公知公用领域,经过市场价值评估后可以无偿使用。     

Regional Fishery Organizations: How and Why Organizational Diversity Matters

Regional fishery organizations are increasingly being viewed as "vehicles of good governance" created to secure the sustainable development of international fisheries. These political expectations have not been followed by analytical refinement of how to explain and understand their formation, roles, objectives, institutional setups, or efficiency. This article provides a conceptual discussion of regional fishery organizations and introduces an organizational typology as a basis for their study. Thus, an analytical distinction is made between regional fisheries management organizations, regional coordination and development organizations and scientific research organizations. This typology and the evolution of the Law of the Sea, from an open access to the exclusive economic zone regime, are used to analyze the institutional arrangements of regional fishery organizations.     

Sex differences in political leadership in an egalitarian society

We test the contribution of sex differences in physical formidability, education, and cooperation to the acquisition of political leadership in a small-scale society. Among forager-farmers from the Bolivian Amazon, we find that men are more likely to exercise different forms of political leadership, including verbal influence during community meetings, coordination of community projects, and dispute resolution. We show that these differences in leadership are not due to gender per se but are associated with men's greater number of cooperation partners, greater access to schooling, and greater body size and physical strength. Men's advantage in cooperation partner number is tied to their participation in larger groups and to the opportunity costs of women's intrahousehold labor. We argue these results highlight the mutual influence of sexual selection and the sexual division of labor in shaping how women and men acquire leadership.     

Evolution of altruistic cooperation among nascent multicellular organisms

Cooperation is a classic solution to hostile environments that limit individual survival. In extreme cases this may lead to the evolution of new types of biological individuals (e.g., eusocial super‐organisms). We examined the potential for interindividual cooperation to evolve via experimental evolution, challenging nascent multicellular “snowflake yeast” with an environment in which solitary multicellular clusters experienced low survival. In response, snowflake yeast evolved to form cooperative groups composed of thousands of multicellular clusters that typically survive selection. Group formation occurred through the creation of protein aggregates, only arising in strains with high (>2%) rates of cell death. Nonetheless, it was adaptive and repeatable, although ultimately evolutionarily unstable. Extracellular protein aggregates act as a common good, as they can be exploited by cheats that do not contribute to aggregate production. These results highlight the importance of group formation as a mechanism for surviving environmental stress, and underscore the remarkable ease with which even simple multicellular entities may evolve—and lose—novel social traits.     

Maintenance of variation in mutualism by screening

Models of partner choice leading to mutualism raise a conceptual problem: directional selection for high‐quality partners should ultimately erode variation in partner quality. How do we explain the persistence of variation in partner quality observed in nature? The problem arises in all models of partner choice, including screening models, in which a host induces potential symbionts of different quality to screen themselves by assigning them different costs and rewards. Using a screening model in which costs and rewards are sometimes assigned incorrectly, I show that a stable polymorphism can arise because rewards are higher when partners vary in quality than when there is only one type of partner. Partner quality, therefore, undergoes negative frequency‐dependent selection even though there is a preference for high‐quality partners. This also shows that partner choice by screening does not need to be totally accurate to be effective—inaccuracies enable both effective screening and the maintenance of variation.     

The leading eight: social norms that can maintain cooperation by indirect reciprocity

The theory of indirect reciprocation explains the evolution of cooperation among unrelated individuals, engaging in one-shot interaction. Using reputation, a player acquires information on who are worth cooperating and who are not. In a previous paper, we formalized the reputation dynamics, a rule to assign a binary reputation (good or bad) to each player when his action, his current reputation, and the opponent's reputation are given. We then examined all the possible reputation dynamics, and found that there exist only eight reputation dynamics named "leading eight" that can maintain the ESS with a high level of cooperation, even if errors are included in executing intended cooperation and in reporting the observation to the public. In this paper, we study the nature of these successful social norms. First, we characterize the role of each pivot of the reputation dynamics common to all of the leading eight. We conclude that keys to the success in indirect reciprocity are to be nice (maintenance of cooperation among themselves), retaliatory (detection of defectors, punishment, and justification of punishment), apologetic, and forgiving. Second, we prove the two basic properties of the leading eight, which give a quantitative evaluation of the ESS condition and the level of cooperation maintained at the ESS.