Christopher Boehm

Violence and Sociality in Human Evolution [and Comments and Replies]

A high gain digital phase comparator which in digital phase lock loop systems can give a thousand-fold reduction in ripple and close-in noise sideband amplitudes. The comparator is of the sample-and-hold type but the normal ramp reference waveform is replaced by a trapezoidal waveform with a very steep rising or falling slope generated by a trapezoidal waveform generator. This slope is sampled by a sampling circuit coupled to said generator and its steepness gives the increased gain of the phase comparator leading to the reduced noise and ripple. Additional logic and switching circuits are added to make the comparator operate only during a rising edge of the trapezoidal waveform.

IMPACT OF THE HUMAN EGALITARIAN SYNDROME ON DARWINIAN SELECTION MECHANICS

With nothing more than kin selection and reciprocal altruism theories to work with, the selection basis of human degrees of altruism and cooperation is often difficult to explain. However, during our prehistoric foraging phase, a highly stable egalitarian syndrome arose that had profound effects on Darwinian selection mechanics. The bands insistence on egalitarianism seriously damped male status rivalry and thereby reduced the intensity of selection within the group by reducing phenotypic variation at that level, while powerful social pressure to make decisions consensual at the band level had a similar effect. Consensual decisions also had another effect: they increased variation between groups because entire bands enacted their subsistence strategies collectively and the strategies varied between bands. By reducing the intensity of individual selection and boosting group effects, these behaviors provided a unique opportunity for altruistic genes to be established and maintained. In addition, the egalitarian custom of socially isolating or actively punishing lazy or cheating noncooperators reduced the free‐rider problem. In combination, these phenotypic effects facilitated selection of altruistic genes in spite of some limited free riding. This selection scenario remained in place for thousands of generations, and the result was a shift in the balance of power between individual and group selection in favor of group effects. This new balance today is reflected in an ambivalent human nature that exhibits substantial altruism in addition to selfishness and nepotism.

Emergency Decisions, Cultural-Selection Mechanics, and Group Selection [and Comments and Reply]

Emergency behaviors of nonliterate groups are taken as a useful starting point for demonstrating that decisions can be integrated more directly into cultural analysis and that the explanatory pay-offs can be far-reaching. The methodological feasibility of studying group decisions directly is explored through three exceptional tribal ethnographies with a focus on emergency adaptive problem solving and its implications for both cultural- and gene-selection theory. Urgently discussed decision alternatives become apprehensible to fieldworkers through open group debate, while the reproductive effects of decisions are readily assessed whenever groups act in unison. Implications for the development of a more effective theory of cultural microselection and a truly processual definition of culture in its guided phase are suggested. With respect to long-term genetic evolution, the implications of emergency decision making are extended to foragers, exploring special possibilities that enable genetic group selection to become robust when groups are egalitarian and engage in consensual problem solving. Prehistorically, the verdict is that group-selection effects were amplified at the same time that individual effects were suppressed. On this basis it is hypothesized that the genetic evolution of human cooperative and altruistic tendencies can be explained in part by selection at the level of groups rather than inclusive fitness

Purposive Social Selection and the Evolution of Human Altruism

Normally scientific evolutionary approaches eschew any element of teleology in theorizing about how natural selection processes work, but social decisions pose a problem for this position. This article examines both positive and negative social sanctioning by human groups to show that purposive social selection at the level of phenotype can have parallel effects at the level of genotype, and that social control has shaped human genetic nature profoundly. A small cross-cultural sample of Pleistocene-appropriate foragers is used to suggest that human groups have been favoring generous individuals, for at least 45,000 years, in ways that affect their fitness. The impact on gene pools could have been substantial, given that runaway selection is likely to have been involved. This type of explanation, which takes human purposes into account as part of evolutionary process, offers a new solution for the genetic paradox of altruistic behavior.

The evolutionary development of morality as an effect of dominance behavior and conflict interference

Morality may be defined as the problem solving activities of a moral community, a primary group which uses a wide range of sanctions directly to reduce conflict, which also sanctions perceived causes of conflict, and defines and controls other deviances judged to be antisocial. So defined, morality is a precondition for law. In comparing human with non-human primates, conflict management is one of the most impressive parallels. This empirical parallel is built upon, to construct an evolutionary scenario for the development of morality and law in their proto-forms.

Ancestral Hierarchy and Conflict

Ancestral Pan, the shared predecessor of humans, bonobos, and chimpanzees, lived in social dominance hierarchies that created conflict through individual and coalitional competition. This ancestor had male and female mediators, but individuals often reconciled independently. An evolutionary trajectory is traced from this ancestor to extant hunter-gatherers, whose coalitional behavior results in suppressed dominance and competition, except in mate competition. A territorial ancestral Pan would not have engaged in intensive warfare if we consider bonobo behavior, but modern human foragers have the potential for full-scale war. Although hunter-gatherers are able to resolve conflicts preemptively, they also use mechanisms, such as truces and peace pacts, to mitigate conflict when the costs become too high. Today, humans retain the genetic underpinnings of both conflict and conflict management; thus, we retain the potential for both war and peace.

The natural selection of altruistic traits

Proponents of the standard evolutionary biology paradigm explain human “altruism” in terms of either nepotism or strict reciprocity. On that basis our underlying nature is reduced to a function of inclusive fitness: human nature has to be totally selfish or nepotistic. Proposed here are three possible paths to giving costly aid to nonrelatives, paths that are controversial because they involve assumed pleiotropic effects or group selection. One path is pleiotropic subsidies that help to extend nepotistic helping behavior from close family to nonrelatives. Another is “warfare”—if and only if warfare recurred in the Paleolithic. The third and most plausible hypothesis is based on the morally based egalitarian syndrome of prehistoric hunter-gatherers, which reduced phenotypic variation at the within-group level, increased it at the between-group level, and drastically curtailed the advantages of free riders. In an analysis consistent with the fundamental tenets of evolutionary biology, these three paths are evaluated as explanations for the evolutionary development of a rather complicated human social nature.

Uniquely Human? A Reply to Zoon Politikon: The Evolutionary Origins of Human Political Systems

We provide the most up-to-date evidence available in various behavioral fields in support of the hypothesis that the emergence of bipedalism and cooperative breeding in the hominin line—together with environmental developments that made a diet of meat from large animals adaptive as well as cultural innovation in the form of fire and cooking—created a niche for hominins in which there was a high return for coordinated, cooperative scavenging and hunting of large mammals. This was accompanied by an increasing use of wooden spears and lithic points as lethal hunting weapons that transformed human sociopolitical life. The combination of social interdependence and the availability of such weapons in early hominin society undermined the standard social dominance hierarchy of multimale/multifemale primate groups. The successful sociopolitical structure that ultimately replaced the ancestral social dominance hierarchy was an egalitarian political system in which lethal weapons made possible group control of leaders, and group success depended on the ability of leaders to persuade and of followers to contribute to a consensual decision process. The heightened social value of nonauthoritarian leadership entailed enhanced biological fitness for such leadership traits as linguistic facility, ability to form and influence coalitions, and, indeed, hypercognition in general.

Parasitic Selection and Group Selection: A Study of Conflict Interference in Rhesus and Japanese Macaque Monkeys

Macaques, like baboons, regularly exhibit third party interference in dyadic conflicts. These most hierarchical primates are well known for forming alliances and coalitions, so presence of interference is not surprising. But as a risky helping behavior which prevents damage to other individuals and also reduces levels of agonism in a group, interference does present some special problems for explanation.

Vocal Communication of Pan Troglogytes : “Triangulating” to the Origin of Spoken Language

This chapter develops an expanded adaptation of Hockett’s design features of language, to compare the purely-vocal communication of humans and free-ranging chimpanzees. The hypothesis is that a chimpanzee type of vocal communication system provides an important preadaptation that could have facilitated the origin of human language. This preadaptation consists of a complex and varied repertory of vocal communication signals, the product of a well-bonded territorial community that is subject to constant internal fission and fusion. Because individuals are contimually changing subgroups, this species appears to have a greater variety of reasons to communicate, when out of sight, than does any other nonhuman primate.