On the evolutionary origins of the egalitarian syndrome

The evolutionary emergence of the egalitarian syndrome is one of the most intriguing unsolved puzzles related to the origins of modern humans. Standard explanations and models for cooperation and altruism-reciprocity, kin and group selection, and punishment-are not directly applicable to the emergence of egalitarian behavior in hierarchically organized groups that characterized the social life of our ancestors. Here I study an evolutionary model of group-living individuals competing for resources and reproductive success. In the model, the differences in fighting abilities lead to the emergence of hierarchies where stronger individuals take away resources from weaker individuals and, as a result, have higher reproductive success. First, I show that the logic of within-group competition implies under rather general conditions that each individual benefits if the transfer of the resource from a weaker group member to a stronger one is prevented. This effect is especially strong in small groups. Then I demonstrate that this effect can result in the evolution of a particular, genetically controlled psychology causing individuals to interfere in a bully-victim conflict on the side of the victim. A necessary condition is a high efficiency of coalitions in conflicts against the bullies. The egalitarian drive leads to a dramatic reduction in within-group inequality. Simultaneously it creates the conditions for the emergence of inequity aversion, empathy, compassion, and egalitarian moral values via the internalization of behavioral rules imposed by natural selection. It also promotes widespread cooperation via coalition formation.     

On the origins of hierarchy in complex networks

Hierarchy seems to pervade complexity in both living and artificial systems. Despite its relevance, no general theory that captures all features of hierarchy and its origins has been proposed yet. Here we present a formal approach resulting from the convergence of theoretical morphology and network theory that allows constructing a 3D morphospace of hierarchies and hence comparing the hierarchical organization of ecological, cellular, technological, and social networks. Embedded within large voids in the morphospace of all possible hierarchies, four major groups are identified. Two of them match the expected from random networks with similar connectivity, thus suggesting that nonadaptive factors are at work. Ecological and gene networks define the other two, indicating that their topological order is the result of functional constraints. These results are consistent with an exploration of the morphospace, using in silico evolved networks.     

Origins of narcissism in children

Narcissism levels have been increasing among Western youth, and contribute to societal problems such as aggression and violence. The origins of narcissism, however, are not well understood. Here, we report, to our knowledge, the first prospective longitudinal evidence on the origins of narcissism in children. We compared two perspectives: social learning theory (positing that narcissism is cultivated by parental overvaluation) and psychoanalytic theory (positing that narcissism is cultivated by lack of parental warmth). We timed the study in late childhood (ages 7–12), when individual differences in narcissism first emerge. In four 6-mo waves, 565 children and their parents reported child narcissism, child self-esteem, parental overvaluation, and parental warmth. Four-wave cross-lagged panel models were conducted. Results support social learning theory and contradict psychoanalytic theory: Narcissism was predicted by parental overvaluation, not by lack of parental warmth. Thus, children seem to acquire narcissism, in part, by internalizing parents’ inflated views of them (e.g., “I am superior to others” and “I am entitled to privileges”). Attesting to the specificity of this finding, self-esteem was predicted by parental warmth, not by parental overvaluation. These findings uncover early socialization experiences that cultivate narcissism, and may inform interventions to curtail narcissistic development at an early age.The mythological figure Narcissus was a handsome, self-absorbed, and vain young man who passionately fell in love with his own reflection in the water. “I burn with love for—me!” Narcissus cried, “the spark I kindle is the torch I carry.” Narcissus was unable to stop looking at his own reflection, and he ultimately pined away by the waterside. Psychologists have come to know Narcissus’ personality as narcissism. Although well known in its extreme form as Narcissistic Personality Disorder, narcissism is a personality trait in which people in the general population differ from one another. Narcissists feel superior to others, fantasize about personal successes, and believe they deserve special treatment (1). When narcissists feel humiliated, they are prone to lash out aggressively (2, 3) or even violently (4). Narcissists are also at increased risk for mental health problems, including drug addiction, depression, and anxiety (5). Research shows that narcissism is higher in Western than non-Western countries (6), and suggests that narcissism levels have been steadily increasing among Western youth over the past few decades (7; see ref. 8 for an alternative view).The origins of narcissism, however, are not well understood. Here, we report, to our knowledge, the first prospective longitudinal evidence on the origins of narcissism in children. We pitted two major theories against each other: social learning theory and psychoanalytic theory. Social learning theory holds that children are likely to grow up to be narcissistic when their parents overvalue them: when their parents see them as more special and more entitled than other children (9). When parents overvalue their child, they see their child as “God’s gift to man” (9) and “are under a compulsion to ascribe every perfection to the child—which sober observation would find no occasion to do” (10). Consequently, children might internalize the belief that they are special individuals who are entitled to privileges. In contrast, psychoanalytic theory holds that children are likely to grow up to be narcissistic when their parents lack warmth toward them (11, 12). When parents lack warmth, they express little affection, appreciation, and positive affect toward their child, and they show little enjoyment of their child (13). In such an upbringing, children might place themselves on a pedestal to try to obtain from others the approval they did not receive from their parents.Both theories have received preliminary support. Cross-sectional research finds that adult narcissists are more likely than nonnarcissists to remember their parents as overvaluing and lacking warmth in childhood (14; for overviews, see refs. 15 and 16). These findings are inconclusive, however. First, the studies were cross-sectional, and were therefore unable to investigate direction of effects. Second, the studies were often limited to samples of college students or adults, whereas the origins of narcissism lie in childhood (17, 18). Third, the studies often relied on adults’ retrospective reports of early socialization experiences. It is no surprise that adult narcissists remember their parents overvaluing them: narcissists typically feel admired by many others, even in the face of disconfirming evidence (19).Addressing these limitations, we conducted a four-wave multi-informant prospective longitudinal study on the origins of narcissism in children. We timed the study in late childhood, ages 7–12, a key developmental phase during which individual differences in narcissism first emerge (17, 18). Indeed, research finds that, from this age, narcissism can be assessed validly (17, 18). Children this age are able to form the global evaluations of themselves as a person (e.g., “I am a special person”) (20) that underlie narcissism. Additionally, they have typically outgrown the unrealistically positive, inflated self-views that are normative for younger children (20), making narcissistic self-views nonnormative.Although narcissists feel superior to others and feel entitled to privileges, they are not necessarily satisfied with themselves as a person. That is, narcissism and self-esteem capture two different dimensions of the self (21, 22). As scholars put it, “High self-esteem means thinking well of oneself, whereas narcissism involves passionately wanting to think well of oneself” (2). Additionally, high self-esteem, unlike narcissism, predicts lower levels of anxiety and depression over time (23). An important question, therefore, is whether the socialization experiences that may cultivate narcissism (e.g., parental overvaluation, lack of parental warmth) also foster high self-esteem. We therefore compared the socialization of narcissism with the socialization of self-esteem.Participants were 565 children (ages 7–11 at wave 1) and their parents, 415 mothers and 290 fathers. The study consisted of four 6-mo waves. In each wave, children completed well-established questionnaires to assess narcissism (e.g., “kids like me deserve something extra”) (17), self-esteem (e.g., “kids like me are happy with themselves as a person”) (24), and parental warmth separately for mothers and fathers (e.g., “my father/mother lets me know he/she loves me”) (25); parents completed well-established questionnaires to assess parental overvaluation (e.g., “my child is more special than other children”) (26) and parental warmth (e.g., “I let my child know I love him/her”) (25).     

The origins of the developmental origins theory

Current orthodoxy states that coronary heart disease results from the unhealthy lifestyles of westernized adults together with a contribution from genetic inheritance. This does not provide a secure basis for prevention of the disease. Geographical studies gave the first clue that the disease originates during intra-uterine development. Variations in mortality from the disease across England and Wales were shown to correlate closely with past differences in death rates among newborn babies. In the past most deaths among newborns were attributed to low birthweight. This led to the hypothesis that undernutrition in utero permanently changes the body's structure, function and metabolism in ways that lead to coronary heart disease in later life. The association between low birthweight and coronary heart disease has been confirmed in longitudinal studies of men and women around the world. The developmental model of the origins of the disease offers a new way forward.     

Generation of the (auto)-antibody repertoire: a case of narcissism?

The immune system has the tremendous task of recognizing and eliminating a practically unlimited number of foreign and often harmful substances. To reach that goal, it has evolved as an apparatus generating a vast array of different antigen receptors expressed by T and B lymphocytes. Through these receptors, the cells can recognize, and respond to, foreign structures; nevertheless, the lymphocytes do not normally react to the body's own constituents. The processes that safeguard a sufficiently broad diversity and yet prevent potentially pathogenic autoimmune reactivity are only now beginning to be elucidated. We describe some of the mechanisms that are believed to play a major role in the generation of the B lymphocyte and antibody repertoire, the induction of tolerance against autologous components and the production of pathogenic autoantibodies, once tolerance is broken.     

Concordance between parental and children's reports of parental smoking prompts

STUDY OBJECTIVES: To describe the prevalence of parental prompting to smoke (eg, parent requests that their child light the parent's cigarette in his/her own mouth) in a sample of families, and to assess the agreement between child and parent reports of the prompting behaviors. DESIGN, SETTING, AND PARTICIPANTS: A total of 3,624 adolescents from 10 middle/junior high schools completed baseline surveys. Parents identified as smokers in these surveys were contacted to complete a telephone survey. These analyses included 270 parent/child pairs. Fifty-one percent of parents were Latino American, 51% had the equivalent of a high-school diploma, 83% were employed when surveyed, and the median household monthly income was between $2,200 and $2,599. Measurements and results: Students completed a paper-and-pencil survey assessing demographic characteristics, seven parental prompts to smoke, past month smoking, parental smoking, acculturation, and familism. A similar questionnaire was developed to collect information by telephone from smoking parents. Concordance between child- and parent-reported prompting was > 85% for five of seven prompts. However, the reported prevalence of six of the seven prompts was lower among parents than children. Thirty-two percent of mothers and 17% of fathers reported prompting their children to bring cigarettes to parents (the most common prompt). Students reported that 62% of their mothers and 54% of their fathers prompted them to bring their cigarettes, a substantial discrepancy in both cases. CONCLUSIONS: Child-reported prompting prevalence was consistently higher than parents' reports, with the biggest discrepancies between requests to clean ashtrays and bring cigarettes, the two most common prompts. In subsequent studies of parental prompting, it is advisable to collect data from both children and parents and to validate the accuracy of the sources.     

Adaptive mutations in Escherichia coli as a model for the multiple mutational origins of tumors.

The cells in most tumors are found to carry multiple mutations; however, based upon mutation rates determined by fluctuation tests, the frequency of such multiple mutations should be so low that tumors are never detected within human populations. Fluctuation tests, which determine the cell-division-dependent mutation rate per cell generation in growing cells, may not be appropriate for estimating mutation rates in nondividing or very slowly dividing cells. Recent studies of time-dependent, "adaptive" mutations in nondividing populations of microorganisms suggest that similar measurements may be more appropriate to understanding the mutation origins of tumors. Here I use the ebgR and ebgA genes of Escherichia coli to measure adaptive mutation rates where multiple mutations are required for rapid growth. Mutations in either ebgA or ebgR allow very slow growth on lactulose (4-O-beta-D-galactosyl-D-fructose), with doubling times of 3.2 and 17.3 days, respectively. However, when both mutations are present, cells can grow rapidly with doubling times of 2.7 hr. I show that during prolonged (28-day) selection for growth on lactulose, the number of lactulose-utilizing mutants that accumulate is 40,000 times greater than can be accounted for on the basis of mutation rates measured by fluctuation tests, but is entirely consistent with the time-dependent adaptive mutation rates measured under the same conditions of prolonged selection.     

On the origins of life’s homochirality: Inducing enantiomeric excess with spin-polarized electrons

Life as we know it is homochiral, but the origins of biological homochirality on early Earth remain elusive. Shallow closed-basin lakes are a plausible prebiotic environment on early Earth, and most are expected to have significant sedimentary magnetite deposits. We hypothesize that ultraviolet (200- to 300-nm) irradiation of magnetite deposits could generate hydrated spin-polarized electrons sufficient to induce enantioselective prebiotic chemistry. Such electrons are potent reducing agents that drive reduction reactions where the spin polarization direction can enantioselectively alter the reaction kinetics. Our estimate of this chiral bias is based on the strong effective spin-orbit coupling observed in the chiral-induced spin selectivity (CISS) effect, as applied to energy differences in reduction reactions for different isomers. In the original CISS experiments, spin-selective electron transmission through a monolayer of double-strand DNA molecules is observed at room temperature—indicating a strong coupling between molecular chirality and electron spin. We propose that the chiral symmetry breaking due to the CISS effect, when applied to reduction chemistry, can induce enantioselective synthesis on the prebiotic Earth and thus facilitate the homochiral assembly of life’s building blocks.

Chirality is a geometric property, and a molecule that cannot be superimposed on its mirror image is said to be chiral (1). Chiral molecules can be conventionally classified based on their handedness as right-handed (D) or left-handed (L) objects (2). Molecules with opposite handedness (called enantiomers) show identical chemical behavior, although biology is picky when it comes to chirality. Essential molecules for life amino acids and sugars are selectively used in only one handedness. All biological systems predominantly use left-handed amino acids and right-handed sugars. Therefore, homochirality is considered to be a signature of life, and understanding the origins of homochirality is essential for understanding the origins of life. However, the origins of biological homochirality remain an open problem. Nonetheless, it is often acknowledged that its early emergence (e.g., during the prebiotic synthesis of the monomers) would be very advantageous in achieving the efficient polymerization of RNA, which is inhibited in a racemic mixture of nucleotides (3, 4).Reaching a homochiral state requires at least two things: first, a chiral symmetry-breaking agent that can induce an enantiomeric excess [ee; % ee = 100 × (L –D)/(L + D)] and second, a prebiotically plausible mechanism that can amplify this imbalance (4). Regarding the latter, a number of asymmetric amplification mechanisms have been proposed. Soai and coworkers (5) has reported that asymmetric autocatalysis can generate nearly perfect ee with high yields—although the conditions are not prebiotically plausible. Blackmond and coworkers (6) demonstrated that RNA precursors can be enantioenriched by chiral amino acids in the Powner–Sutherland ribonucleotide synthesis (7). Their scheme showed amplification in the ee of pyrimidine nucleotide precursors, such as glyceraldehyde and aminooxazolines. Blackmond and coworkers (8) also showed that chiral pentose sugars can enantioenrich amino acid precursors with substantial amplification. Their analysis revealed a significant dynamic kinetic resolution that can take advantage of the selective reaction rates for enantiomers and amplify a small ee into near unity. In combination, these results indicate that sugars can trigger the enantioenrichment of amino acids and vice versa, and inducing a small ee can be sufficient to reach an enantiomerically pure state. However, the search for a prebiotically plausible asymmetric amplification mechanism is still active (9). In this work, we are investigating a symmetry-breaking agent that can trigger such an amplification mechanism.Many chiral symmetry-breaking agents have been proposed—circularly polarized light (CPL), magnetic fields, cosmic rays, and weak nuclear currents to name a few (10–15). These symmetry-breaking agents induce ee by either selectively producing or destroying one isomer more than the other. Studies with CPL take advantage of the optical activity of chiral molecules, and it has been shown that a nearly enantiopure state is reached with the amplification of a slight ee induced by CPL (10, 11, 16). However, the efficiency of CPL is low, and the source and availability of CPL on the early Earth are unclear. Utilizing optical activity of chiral molecules, albeit using unpolarized light in an external magnetic field, Rikken and Raupach (12) demonstrated that an ee of about 100 ppm can be generated. Although this so-called magnetochiral excess is realized with unpolarized light, it relies on the presence of external fields as high as 10 T. Polarized cosmic rays have been theorized as a universal enantioselective agent, inducing a bias during the evolution of two biosystems with opposite handedness (13). Experimental support has come from enantioselective destruction due to dissociative electron attachment (DEA) with low-energy longitudinally polarized electrons by Dreiling and Gay (17), highlighting the viability of longitudinally polarized cosmic beta radiation to do that. Prior experiments by Rosenberg et al. (18) presented a different version of DEA and demonstrated enantioselective destruction of a racemic adsorbed layer of chiral molecules yet with an alternative chiral symmetry-breaking agent: spin-polarized low-energy (a few electronvolts) secondary electrons. The effect they observed is the enantioselective destruction of a chemical bond via high-energy scattering under ultrahigh-vacuum conditions, and it appears to be due to a strong coupling between the spin-polarized electrons and the molecular chiral center (18, 19).We suggest that the same strong coupling induces enantioselectivity but with a different source and mechanism. We propose an enantioselective reduction chemistry, in solution, induced by spin-polarized photoelectrons ejected from a magnetized surface, as shown in Fig. 1. The mechanism we suggest is yield preserving as it drives enantioselective production, not destruction. It operates under conditions that are compatible with the conditions of a reduction chemistry at room temperature in solution. The core of our mechanism is the spin–chirality interaction. However, how does spin interact with molecular chirality and induce enantioselective chemistry?Open in a separate windowFig. 1.An evaporative lake with magnetite deposits contains the feedstock molecules for prebiotic chemistry. Irradiation of the uniformly magnetized magnetite (Fe₃O₄) deposits with solar UV (200- to 300-nm) light generates helical photoelectrons. The helicity of the electrons (D–e–in the figure as the spin and momentum are parallel to each other) is determined by the magnetization direction (section 3 discusses what is meant by the electron helicity). Helical electrons induce CDRC near the magnetite surface due to a selectivity in the reaction rates, k_L and k_D, for different isomers L and D, respectively. This selectivity in the reaction rates can induce an imbalance between two isomers. In the figure, ee in the L isomer is induced.