For more than 100,000 years, H. sapiens lived as foragers, in small family groups with low reproductive variance. A minority of men were able to father children by two or three women; and a majority of men and women were able to breed. But after the origin of farming around 10,000 years ago, reproductive variance increased. In civilizations which began in Mesopotamia, Egypt, India, and China, and then moved on to Greece and Rome, kings collected thousands of women, whose children (...) were supported and guarded by thousands of eunuchs. Just a few hundred years ago, that trend reversed. Obligate sterility ended, and reproductive variance declined. For H. sapiens, as for other organisms, eusociality seems to be an effect of ecological constraints. Civilizations rose up in lake and river valleys, hemmed in by mountains and deserts. Egalitarianism became an option after empty habitats opened up. (shrink)

For more than 100,000 years, H. sapiens lived as foragers, in small family groups with low reproductive variance. A minority of men were able to father children by two or three women; and a majority of men and women were able to breed. But after the origin of farming around 10,000 years ago, reproductive variance increased. In civilizations which began in Mesopotamia, Egypt, India, and China, and then moved on to Greece and Rome, kings collected thousands of women, whose children (...) were supported and guarded by thousands of eunuchs. Just a few hundred years ago, that trend reversed. Obligate sterility ended, and reproductive variance declined. For H. sapiens, as for other organisms, eusociality seems to be an effect of ecological constraints. Civilizations rose up in lake and river valleys, hemmed in by mountains and deserts. Egalitarianism became an option after empty habitats opened up. (shrink)

Eusociality is the form of animal social organization with a reproductive division of labor, most prominently known from ants and bees. Here I ask the question why this enormously successful form of social organization is missing in the largest and most diverse group of vertebrates, the teleost fishes. I first briefly review the phylogenetic distribution and likely evolutionary origins of eusociality. Then, after an equally very brief review of the diverse life history strategies of teleosts, I conclude that (...) it is not the lack of evolutionary pre-adaptations which is keeping teleosts from becoming eusocial. Rather, I argue, that the absence of eusocial fish is caused by a number of differences between aquatic (chiefly marine) and terrestrial ecosystems: (1) Greater offspring dispersal in aquatic ecosystems reduces the role of kin-selection. (2) Lesser predictability of the environment at larger timescales in marine ecosystems disfavors eusociality. (3) A briefer impact of resource pulses in aquatic ecosystems will cause less evolutionary pressure towards cooperation, and eventually eusociality. Finally, I conclude by predicting that the most likely places to find eusocial fishes will be the deep-water regions of the ocean and the African rift lakes. (shrink)

I propose that a dishonest signaling system can be evolutionarily stable in eusocial animal societies if the amount of dishonesty is balanced by the chance of non-reproductive workers to advance to the reproductive caste in the future. I express this trade-off in a modified form of Hamilton’s rule, where I distinguish between the real and perceived cost of an altruistic act, and between the real and perceived genetic relatedness between colony members. Furthermore, I elaborate how the vertebrate neuromodulator oxytocin could (...) serve as an internal representation of the perceived cost of an altruistic act and of perceived relatedness. Behavioral and receptor localization data support this hypothesis. The encoding of cost and relatedness by oxytocin is likely integrated with a number of other functions related to social bonding. I conclude with a discussion of honesty in signaling, an outline of testable consequences of this hypothesis, and a comparison between vertebrate and insect eusociality. (shrink)

Eusociality is broadly defined as: colonies consisting of overlapping generations, cooperative brood care, and a reproductive division of labour where sterile (or non-reproductive) workers help the reproductive members. Colonies of many complex eusocial insect species (e.g. ants, bees, termites) exhibit traits, at the collective level, that are more analogous to biological individuals rather than to groups. Indeed, due to this, colonies of the most complex species are typically a unit of selection, which has led many authors to once again (...) apply the concept of the superorganism to eusocial insects. However, unlike W. M. Wheeler, who originally employed the concept from a physiological and evolutionary perspective, today the superorganism is typically understood only from an evolutionary perspective, using group selection. This is because of the widely held view that eusocial colonies are self-organized systems. According to this view, even the most complex eusocial systems can be explained by appealing to a set of local interactions between parts of an initially disordered system (i.e. self-organization), without the need of any hierarchical control. In this paper we challenge the presupposition that hierarchical control and regulation is not possible in complex eusocial colonies. Using a case study of honey bees (Apis mellifera), we develop an alternative to the self-organization approach, that focuses on the hierarchical nature of the organization of complex eusocial systems—that we refer to as the hierarchical-organizational approach. In addition, we will analyse how colonies of eusocial insects show a complex set of interactions between the different organisms that bring forth a new cohesive collective organization, and how in turn the constitutive entities of this collective organization are transformed in this process. This paper argues that an inter-identity (namely the superorganism) emerges at the collective level in complex eusocial colonies, such as honey bees, due to the hierarchically-organized network of interactions within the colony. (shrink)

Fisher recognized that the evolution of social insect colonies needed explaining, a point which Charles Darwin had avoided discussing in detail. Fisher, in his 1930 book The Genetical Theory of Natural Selection, outlined in detail how eusociality could evolve, and developed a verbal model by connecting selection on fecundity with the sterility of workers. Fisher saw social insect colonies as harmonious units, in contrast to human societies that exhibit intra-communal conflict. Fisher’s development of the model was strongly influenced by (...) his correspondence with Leonard Darwin, and so I call it the Fisher-Darwin model. However, Fisher was not influenced by Lamarckian views on the evolution of social insects that were common at that time. The Fisher-Darwin model presages almost exactly the mathematical model recently proposed by Nowak and colleagues. (shrink)

Honey bees are eusocial insects and the workers inform their nestmates of information regarding the location of food source using symbolic communication, called ‘dance communication’, that are based on their highly advanced learning abilities. Mushroom bodies (MBs), a higher-order center in the honey bee brain, comprise some subtypes/populations of interneurons termed Kenyon cells (KCs) that are distinguished by their cell body size and location in the MBs, as well as their gene expression profiles. Although the role of MBs in learning (...) ability has been studied extensively in the honey bee, the roles of each KC subtype and their evolution in hymenopteran insects remain mostly unknown. This mini-review describes recent progress in the analysis of gene/protein expression profiles and possible functions of KC subtypes/populations in the honey bee. Especially, the discovery of novel KC subtype/population, ‘middle-type KCs’ and ‘KC population expressing FoxP’, necessitated a redefinition of the KC subtype/population. Analysis of the effects of inhibiting gene function in a KC subtype-preferential manner revealed the function of the gene product as well as of the subtype where it is expressed. Genes expressed in a KC subtype/population-preferential manner can be used to trace the differentiation of KC subtypes during the honey bee ontogeny and the possible evolution of KC subtypes in hymenopteran insects. Current findings suggest that the three KC subtypes are unique characteristics to the aculeate hymenopteran insects. Finally, recent application of genome editing for the study of KC subtype functions in the honey bee is described. Genes expressed in a KC subtype-preferential manner can be good candidate target genes for genome editing, because they are likely related to highly advanced brain functions and some of them are dispensable for normal development and sexual maturation in honey bees. (shrink)

Three decades after Chalmers named it, the ‘hard problem’ remains. I suggest a parsimonious solution. Biological dynamic systems interact according to simple rules (while the environment provides simple constraints) and thus self-organize to become a new, more complex dynamic system at the next level. This spiral repeats several times generating a hierarchy of levels. A leap to the next level is frequently creative and surprising. From ants, themselves self-organized according to physical/chemical laws, may emerge an ant colony self-organized according to (...) eusocial laws. A dynamic system need not be material. A living language (immaterial) is a complex adaptive system. Body/brain are material but the next level of complexity, a psychological dynamic system, a thought, feeling, image or ideal, is less material. From several psychological dynamic systems emerges the next level, narrative (immaterial), and from multiple narratives emerges personality. Concrete evidence explains how an early narrative emerges from body-and-brain. Evidence also shows that personality emerges from narrative. Even an objective narrative captures subjectivity since the teller’s choice of content is subjective. I argue that the ‘stream-of-consciousness’ story (movie) you are currently telling yourself (watching) is your conscious experience, ‘what it is like’ for you to be conscious. Adriana Cavarero’s arguments support this. Each level of a hierarchy of dynamic systems must necessarily be homeostatic, at that level. McDowell et al. (2023: submitted, in revision) reported evidence that a dream (a narrative) supports personality homeostatically. Perhaps the evolutionary advantage of conscious experience, also a narrative, has always been that it too supports personality homeostatically. Personality and body/brain, a chimera of symbiotic life-forms, constitute interactionist duality. (shrink)

Inclusive fitness theory was not originally designed to explain the major transitions in evolution, but there is a growing consensus that it has the resources to do so. My aim in this paper is to highlight, in a constructive spirit, the puzzles and challenges that remain. I first consider the distinctive aspects of the cooperative interactions we see within the most complex social groups in nature: multicellular organisms and eusocial insect colonies. I then focus on one aspect in particular: the (...) extreme redundancy these societies exhibit. I argue that extreme redundancy poses a distinctive explanatory puzzle for inclusive fitness theory, and I offer a potential solution which casts coercion as the key enabler. I suggest that the general moral to draw from the case is one of guarded optimism: while inclusive fitness is a powerful tool for understanding evolutionary transitions, it must be integrated within a broader framework that recognizes the distinctive problems such transitions present and the distinctive mechanisms by which these problems may be overcome. (shrink)

Understanding how cooperation evolves is central to explaining some core features of our biological world. Many important evolutionary events, such as the arrival of multicellularity or the origins of eusociality, are cooperative ventures between formerly solitary individuals. Explanations of the evolution of cooperation have primarily involved showing how cooperation can be maintained in the face of free-riding individuals whose success gradually undermines cooperation. In this paper I argue that there is a second, distinct, and less well explored, problem of (...) cooperation that I call the generation of benefit. Focusing on how benefit is generated within a group poses a different problem: how is it that individuals in a group can (at least in principle) do better than those who remain solitary? I present several different ways that benefit may be generated, each with different implications for how cooperation might be initiated, how it might further evolve, and how it might interact with different ways of maintaining cooperation. I argue that in some cases of cooperation, the most important underlying “problem” of cooperation may be how to generate benefit, rather than how to reduce conflict or prevent free-riding. (shrink)

Evolutionary Transitions in Individuality have been responsible for the major transitions in levels of selection and individuality in natural history, such as the origins of prokaryotic and eukaryotic cells, multicellular organisms, and eusocial insects. The integrated hierarchical organization of life thereby emerged as groups of individuals repeatedly evolved into new and more complex kinds of individuals. The Social Protocell Hypothesis proposes that the integrated hierarchical organization of human culture can also be understood as the outcome of an ETI—one that produced (...) a “cultural organism” from a substrate of socially learned traditions that were contained in growing and dividing social communities. The SPH predicts that a threshold degree of evolutionary individuality would have been achieved by 2.0–2.5 Mya, followed by an increasing degree of evolutionary individuality as the ETI unfolded. We here assess the SPH by applying a battery of criteria—developed to assess evolutionary individuality in biological units—to cultural units across the evolutionary history of Homo. We find an increasing agreement with these criteria, which buttresses the claim that an ETI occurred in the cultural realm. (shrink)

The role of genetic relatedness in social evolution has recently come under critical attention. These arguments are here critically analyzed, both theoretically and empirically. It is argued that when the conceptual structure of the theory of natural selection is carefully taken into account, genetic relatedness can be seen to play an indispensable role in the evolution of both facultative and advanced eusociality. Although reviewing the empirical evidence concerning the evolution of eusociality reveals that relatedness does not play a (...) role in the initial appearance of helper phenotypes, this follows simply from the fact that natural selection – of which relatedness is a necessary component – does not play a causal role in the origin of any traits. Further, separating two logically distinct elements of causal explanation – necessity and sufficiency – explains why the debate lingers on: although relatedness plays a necessary role in the evolution of helping and advanced eusociality, relatedness alone is not sufficient for their appearance. Therefore, if the relatedness variable in a given data set is held at a uniformly high value, then it indeed may turn out that other factors occupy a more prominent role. However, this does not change the fact that high relatedness functions as a necessary background condition for the evolution of advanced eusociality. (shrink)

Forgiveness is a hallmark teaching within monotheistic religions. This Element introduces the topic in three ways. First, it considers the extent to which forgiveness is specific to or constituted by monotheistic beliefs, by a comparison with analogous teaching and practice in Buddhism. Second, the most extensive section explores the grammar of forgiveness shared across the Abrahamic traditions of Judaism, Christianity and Islam – elements of repentance, intercession, and eschatological deferral. This section identifies some of the divergent tendencies or emphases on (...) this topic among those traditions. A third section addresses the role of forgiveness and monotheistic religions in human cultural evolution and the emergence of eusociality. The aim is for the reader to gain an introductory view of monotheism and forgiveness from a comparative religious example, from an internal examination of Abrahamic traditions, and from a developmental, secular perspective. (shrink)

The paper gives an overview of primate research and the economic-ethical 'lessons' we can derive from it. In particular, it examines the complex, multi-faceted and partially conflicting nature of (non-) human primates. Our closest living relatives, the chimpanzees and bonobos, apparently walk on two legs: a selfish and a groupish leg. Given evolutionary continuity and gradualism between monkeys, apes and humans, human primates seem to be bipolar apes as well. They, too, tend to display a dual structure: there seems to (...) be a pro-social and a self-interested side to our species and a bipolar tension seems to exist between competition and cooperation respectively between self-interest and the common good. We are apparently at the same time Homines oeconomici and Homines culturali. Our inner ape tries to combine self-interested and common good motives. Based on de Waal's Russian doll model, the essay investigates the evolutionary origins of morality and 'eusociality'. With the help of selected case studies stemming from behavioural sciences/economics, the paper illustrates examples of empathy, altruism, reciprocal fairness, pro-social and other-regarding preferences, inequity aversion and altruistic punishment in (non-)human primates. Beside this selfless and groupish side, the paper also reflects on the self-interest and egoistic nature of (non-)human primates and the behavioural and cognitive differences between monkeys, apes and humans. (shrink)

Leo Pardi was the initiator of ethological research in Italy. During more than 50 years of active scientific career, he gave groundbreaking contributions to the understanding of social life in insects, especially in Polistes wasps, an important model organism in sociobiology. In the 1940s, Pardi showed that Polistes societies are organized in a linear social hierarchy that relies on reproductive dominance and on the physiological and developmental mechanisms that regulate it, i.e. on the status of ovarian development of single wasps. (...) Pardi’s work set the stage for further research on the regulatory mechanisms governing social life in primitively eusocial organisms both in wasps and in other insect species. This article reconstructs Pardi’s investigative pathway between 1937 and 1952 in the context of European ethology and American animal sociology. This reconstruction focuses on the development of Pardi’s physiological approach and presents a new perspective on the interacting development of these two fields at the origins of our current understanding of animal social behavior. (shrink)

Edward O. Wilson’s recent decision to abandon kin selection theory has sent shockwaves throughout the biological sciences. Over the past two years, more than a hundred biologists have signed letters protesting his reversal. Making sense of Wilson’s decision and the controversy it has spawned requires familiarity with the historical record. This entails not only examining the conditions under which kin selection theory first emerged, but also the organicist tradition against which it rebelled. In similar fashion, one must not only examine (...) Wilson’s long career, but also those thinkers who influenced him most, especially his intellectual grandfather, William Morton Wheeler (1865–1937). Wilson belongs to a long line of organicists, biologists whose research highlighted integration and coordination, many of whom struggled over the exact same biological riddles that have long defined Wilson’s career. Drawing inspiration (and sometimes ideas) from these intellectual forebears, Wilson is confident that he has finally identified the origin of the social impulse. (shrink)

For the past 500 years, to varying degrees, the processes of religious secularization have been occurring in what today are the wealthy, highly educated, industrialized nations of the world. They are causing organized religion, as a social institution, to go from being a very important influence on the lives of people and the nations in which they live to being a smaller influence, or almost no influence at all. Various disciplines from theology to psychology to sociology have tried to explain (...) secularization, each discipline contributing something unique. One discipline that has not contributed has been biology. From a biological perspective, based on observation and reasoning, at least one of the ultimate functions of the physical forms associated with religion appear to be that of in-group marker for a breeding population, which, as will be shown, is how all religions start. Religions structure larger human populations into smaller “clusters” that are separate in-group breeding populations. The clustering into smaller in-group breeding populations prevents the spread of contagious diseases and creates inter-group competition and intra-group cooperation, both of which have contributed to human eusociality, a very rare type of social organization that will be explained. As the physical forms of religion are losing this in-group-marker function of clustering populations with modernity, a general biological principle comes into play, which is “form follows function, and as function wanes, so does form.” When applied to religion, “form” means the physical components by which all religions are built. The specific meaning of “physical,” as used here, will be explained in the article. This biological perspective, which is counter-intuitive and can generate testable hypotheses, should complement, not compete, with perspectives from other disciplines. Physical forms in biology can and often do have more than one function, so the same form with a biological function can also have psychological and theological functions. The physical forms of religion are its objects of natural (genetic and cultural) selection. As socio-economic modernity spreads through the world, the evolutionary biological trajectory suggests that religion, as a social institution, will eventually become extinct. (shrink)

This essay argues that economic scarcity, along with mankind’s evolved propensity for reciprocity, are keys to understanding the origins and evolution of Western religion in all its varieties and purposes. Scarcity is religion’s first cause uncaused. Eusocial cooperation and productive efficiency, which are mobilized by religion, are shown to be inherent and rational responses to scarcity. The reformation that began around 1500 CE represents the substitution of efficient secular religions for traditional theological varieties. The balance between traditional and secular religions (...) is determined by cost, benefits, and the structure of economic payoffs. (shrink)

In their target article, Mikhalevich & Powell (M&P) argue that we should extend moral protection to arthropods. In this commentary, we show that there are some unforeseen obstacles to applying the sort of individualistic welfare-based ethics that M&P have in mind to certain arthropods, namely, insects. These obstacles have to do with the fact that there are often many more individuals involved in our dealings with insects than our ethical theories anticipate, and also with the fact that, in some sense, (...) some insects count as more than an individual and, in another sense, they sometimes count as less than an individual. (shrink)