Enforced altruism in insect societies

Cooperation among workers and their seeming altruism result from strict policing by nestmates.     

The nature of human altruism

Some of the most fundamental questions concerning our evolutionary origins, our social relations, and the organization of society are centred around issues of altruism and selfishness. Experimental evidence indicates that human altruism is a powerful force and is unique in the animal world. However, there is much individual heterogeneity and the interaction between altruists and selfish individuals is vital to human cooperation. Depending on the environment, a minority of altruists can force a majority of selfish individuals to cooperate or, conversely, a few egoists can induce a large number of altruists to defect. Current gene-based evolutionary theories cannot explain important patterns of human altruism, pointing towards the importance of both theories of cultural evolution as well as gene-culture co-evolution.     

利他、公平和信任等因素对合作的影响

分析了利他、公平、信任等因素对博弈过程中合作的影响,以典型的"gift-exchange博弈模型"为例,假设博弈方行为受到一些因素影响并且可以用启发式规则简单描述,通过对成员Agent内部的利他、公平、信任等属性和交互过程中启发式规则的设计和编程实现,使得博弈双方在博弈过程中不断学习和调整策略,形成最终达成一致的合作机制.利用多Agent系统平台--JADE对所提出的模型进行仿真,通过对实验数据的分析,揭示了在多Agent系统中利他、公平以及信任等因素对合作的影响,指出了这些因素在经济生活中的实际指导意义.     

Detrimental effects of sanctions on human altruism

The existence of cooperation and social order among genetically unrelated individuals is a fundamental problem in the behavioural sciences. The prevailing approaches in biology and economics view cooperation exclusively as self-interested behaviour--unrelated individuals cooperate only if they face economic rewards or sanctions rendering cooperation a self-interested choice. Whether economic incentives are perceived as just or legitimate does not matter in these theories. Fairness-based altruism is, however, a powerful source of human cooperation. Here we show experimentally that the prevailing self-interest approach has serious shortcomings because it overlooks negative effects of sanctions on human altruism. Sanctions revealing selfish or greedy intentions destroy altruistic cooperation almost completely, whereas sanctions perceived as fair leave altruism intact. These findings challenge proximate and ultimate theories of human cooperation that neglect the distinction between fair and unfair sanctions, and they are probably relevant in all domains in which voluntary compliance matters--in relations between spouses, in the education of children, in business relations and organizations as well as in markets.     

地方工科大学实施大学物理新基本要求的探索与实践

分析了当前地方工科大学实施大学物理课程教学基本要求存在的问题,结合本校实际,在实施新《基本要求》上进行了积极的探索与实践,取得了初步成果。     

利他主义的谜底探究及其当代启示

近些年来,利他主义的谜底探究日益从多学科多领域的理论研究层面转向实践应用前沿.尤其是,利他主义蕴涵的"利他才能更好地利已"的新理念,对于今天人们走出道德与利益的伦理困境,化解社会冲突与矛盾,构建和谐社会,实现全球可持续发展等具有非常重要的启示和指导意义.     

Egalitarian motives in humans

Participants in laboratory games are often willing to alter others' incomes at a cost to themselves, and this behaviour has the effect of promoting cooperation. What motivates this action is unclear: punishment and reward aimed at promoting cooperation cannot be distinguished from attempts to produce equality. To understand costly taking and costly giving, we create an experimental game that isolates egalitarian motives. The results show that subjects reduce and augment others' incomes, at a personal cost, even when there is no cooperative behaviour to be reinforced. Furthermore, the size and frequency of income alterations are strongly influenced by inequality. Emotions towards top earners become increasingly negative as inequality increases, and those who express these emotions spend more to reduce above-average earners' incomes and to increase below-average earners' incomes. The results suggest that egalitarian motives affect income-altering behaviours, and may therefore be an important factor underlying the evolution of strong reciprocity and, hence, cooperation in humans.     

Altruistic punishment in humans.

Human cooperation is an evolutionary puzzle. Unlike other creatures, people frequently cooperate with genetically unrelated strangers, often in large groups, with people they will never meet again, and when reputation gains are small or absent. These patterns of cooperation cannot be explained by the nepotistic motives associated with the evolutionary theory of kin selection and the selfish motives associated with signalling theory or the theory of reciprocal altruism. Here we show experimentally that the altruistic punishment of defectors is a key motive for the explanation of cooperation. Altruistic punishment means that individuals punish, although the punishment is costly for them and yields no material gain. We show that cooperation flourishes if altruistic punishment is possible, and breaks down if it is ruled out. The evidence indicates that negative emotions towards defectors are the proximate mechanism behind altruistic punishment. These results suggest that future study of the evolution of human cooperation should include a strong focus on explaining altruistic punishment.     

Oxytocin increases trust in humans

Trust pervades human societies. Trust is indispensable in friendship, love, families and organizations, and plays a key role in economic exchange and politics. In the absence of trust among trading partners, market transactions break down. In the absence of trust in a country's institutions and leaders, political legitimacy breaks down. Much recent evidence indicates that trust contributes to economic, political and social success. Little is known, however, about the biological basis of trust among humans. Here we show that intranasal administration of oxytocin, a neuropeptide that plays a key role in social attachment and affiliation in non-human mammals, causes a substantial increase in trust among humans, thereby greatly increasing the benefits from social interactions. We also show that the effect of oxytocin on trust is not due to a general increase in the readiness to bear risks. On the contrary, oxytocin specifically affects an individual's willingness to accept social risks arising through interpersonal interactions. These results concur with animal research suggesting an essential role for oxytocin as a biological basis of prosocial approach behaviour.     

Cortical substrates for exploratory decisions in humans

Decision making in an uncertain environment poses a conflict between the opposing demands of gathering and exploiting information. In a classic illustration of this 'exploration-exploitation' dilemma, a gambler choosing between multiple slot machines balances the desire to select what seems, on the basis of accumulated experience, the richest option, against the desire to choose a less familiar option that might turn out more advantageous (and thereby provide information for improving future decisions). Far from representing idle curiosity, such exploration is often critical for organisms to discover how best to harvest resources such as food and water. In appetitive choice, substantial experimental evidence, underpinned by computational reinforcement learning (RL) theory, indicates that a dopaminergic, striatal and medial prefrontal network mediates learning to exploit. In contrast, although exploration has been well studied from both theoretical and ethological perspectives, its neural substrates are much less clear. Here we show, in a gambling task, that human subjects' choices can be characterized by a computationally well-regarded strategy for addressing the explore/exploit dilemma. Furthermore, using this characterization to classify decisions as exploratory or exploitative, we employ functional magnetic resonance imaging to show that the frontopolar cortex and intraparietal sulcus are preferentially active during exploratory decisions. In contrast, regions of striatum and ventromedial prefrontal cortex exhibit activity characteristic of an involvement in value-based exploitative decision making. The results suggest a model of action selection under uncertainty that involves switching between exploratory and exploitative behavioural modes, and provide a computationally precise characterization of the contribution of key decision-related brain systems to each of these functions.     

Earliest presence of humans in northeast Asia

The timing of the earliest habitation and oldest stone technologies in different regions of the world remains a contentious topic in the study of human evolution. Here we contribute to this debate with detailed magnetostratigraphic results on two exposed parallel sections of lacustrine sediments at Xiaochangliang in the Nihewan Basin, north China; these results place stringent controls on the age of Palaeolithic stone artifacts that were originally reported over two decades ago. Our palaeomagnetic findings indicate that the artifact layer resides in a reverse polarity magnetozone bounded by the Olduvai and Jaramillo subchrons. Coupled with an estimated rate of sedimentation, these findings constrain the layer's age to roughly 1.36 million years ago. This result represents the age of the oldest known stone assemblage comprising recognizable types of Palaeolithic tool in east Asia, and the earliest definite occupation in this region as far north as 40 degrees N.     

Dynamics of fat cell turnover in humans

Obesity is increasing in an epidemic manner in most countries and constitutes a public health problem by enhancing the risk for cardiovascular disease and metabolic disorders such as type 2 diabetes. Owing to the increase in obesity, life expectancy may start to decrease in developed countries for the first time in recent history. The factors determining fat mass in adult humans are not fully understood, but increased lipid storage in already developed fat cells (adipocytes) is thought to be most important. Here we show that adipocyte number is a major determinant for the fat mass in adults. However, the number of fat cells stays constant in adulthood in lean and obese individuals, even after marked weight loss, indicating that the number of adipocytes is set during childhood and adolescence. To establish the dynamics within the stable population of adipocytes in adults, we have measured adipocyte turnover by analysing the integration of 14C derived from nuclear bomb tests in genomic DNA. Approximately 10% of fat cells are renewed annually at all adult ages and levels of body mass index. Neither adipocyte death nor generation rate is altered in early onset obesity, suggesting a tight regulation of fat cell number in this condition during adulthood. The high turnover of adipocytes establishes a new therapeutic target for pharmacological intervention in obesity.     

Temporal difference models describe higher-order learning in humans

The ability to use environmental stimuli to predict impending harm is critical for survival. Such predictions should be available as early as they are reliable. In pavlovian conditioning, chains of successively earlier predictors are studied in terms of higher-order relationships, and have inspired computational theories such as temporal difference learning. However, there is at present no adequate neurobiological account of how this learning occurs. Here, in a functional magnetic resonance imaging (fMRI) study of higher-order aversive conditioning, we describe a key computational strategy that humans use to learn predictions about pain. We show that neural activity in the ventral striatum and the anterior insula displays a marked correspondence to the signals for sequential learning predicted by temporal difference models. This result reveals a flexible aversive learning process ideally suited to the changing and uncertain nature of real-world environments. Taken with existing data on reward learning, our results suggest a critical role for the ventral striatum in integrating complex appetitive and aversive predictions to coordinate behaviour.