Chimpanzee and hunter-gatherer intergroup aggression differ in important ways, including humans having the ability to form peaceful relationships and alliances among groups. This paper nevertheless evaluates the hypothesis that intergroup aggression evolved according to the same functional principles in the two species—selection favoring a tendency to kill members of neighboring groups when killing could be carried out safely. According to this idea chimpanzees and humans are equally risk-averse when fighting. When self-sacrificial war practices are found in humans, therefore, they result (...) from cultural systems of reward, punishment, and coercion rather than evolved adaptations to greater risk-taking. To test this “chimpanzee model,” we review intergroup fighting in chimpanzees and nomadic hunter-gatherers living with other nomadic hunter-gatherers as neighbors. Whether humans have evolved specific psychological adaptations for war is unknown, but current evidence suggests that the chimpanzee model is an appropriate starting point for analyzing the biological and cultural evolution of warfare. (shrink)

Parallels in anatomy between humans and domesticated mammals suggest that for the last 300,000 years, Homo sapiens has experienced more intense selection against the propensity for reactive aggression than any other species of Homo. Selection against reactive aggression, a process that can also be called self-domestication, would help explain various physiological, behavioral and cognitive features of humans, including the unique system of egalitarian male hierarchy in mobile hunter-gatherers. Here I review nine leading proposals that could potentially explain why self-domestication occurred (...) in H. sapiens, whether by selecting in favor of cooperation and tolerance or by selecting against aggressiveness. To account for the domestication syndrome, proposals must explain what led to a decline in fitness of highly aggressive males, and why the explanatory factor applies only to H. sapiens rather than to other species of Homo. The proposed explanations invoke genetic group selection; group-structured culture selection (also known as cultural group selection); social selection by female mate choice; social selection by male partner choice; increased self-control; cooperative breeding; high population density; use of lethal weapons; and language-based conspiracy. Most proposals face difficulties in accounting for the origins and/or maintenance of self-domestication. I conclude that the evolution of language-based conspiracy, which is a form of collective intentionality, was the key factor initiating and maintaining self-domestication in H. sapiens, because it is the most convincing mechanism for explaining the selective pressure against individually powerful fighters. Sophisticated language enabled males of low fighting prowess to coordinate in executing physically aggressive and domineering alpha males. This system is known today as a leveling mechanism in small-scale societies. Group-structured culture selection possibly accelerated the process. (shrink)

The evolution of nonconceptive sexuality in bonobos and chimpanzees is discussed from a functional perspective. Bonobos and chimpanzees have three functions of sexual activity in common (paternity confusion, practice sex, and exchange for favors), but only bonobos use sex purely for communication about social relationships. Bonobo hypersexuality appears closely linked to the evolution of female-female alliances. I suggest that these alliances were made possible by relaxed feeding competition, that they were favored through their effect on reducing sexual coercion, and that (...) they are ultimately responsible for the relaxed social conditions that allowed the evolution of “communication sex.”. (shrink)

In the absence of explicit punitive sanctions, why do individuals voluntarily participate in intergroup warfare when doing so incurs a mortality risk? Here we consider the motivation of individuals for participating in warfare. We hypothesize that in addition to other considerations, individuals are incentivized by the possibility of rewards. We test a prediction of this “cultural rewards war-risk hypothesis” with ethnographic literature on warfare in small-scale societies. We find that a greater number of benefits from warfare is associated with a (...) higher rate of death from conflict. This provides preliminary support for the relationship between rewards and participation in warfare. (shrink)

Many male traits are well explained by sexual selection theory as adaptations to mating competition and mate choice, whereas no unifying theory explains traits expressed more in females. Anne Campbell's “staying alive” theory proposed that human females produce stronger self-protective reactions than males to aggressive threats because self-protection tends to have higher fitness value for females than males. We examined whether Campbell's theory has more general applicability by considering whether human females respond with greater self-protectiveness than males to other threats (...) beyond aggression. We searched the literature for physiological, behavioral, and emotional responses to major physical and social threats, and found consistent support for females' responding with greater self-protectiveness than males. Females mount stronger immune responses to many pathogens; experience a lower threshold to detect, and lesser tolerance of, pain; awaken more frequently at night; express greater concern about physically dangerous stimuli; exert more effort to avoid social conflicts; exhibit a personality style more focused on life's dangers; react to threats with greater fear, disgust, and sadness; and develop more threat-based clinical conditions than males. Our findings suggest that in relation to threat, human females have relatively heightened protective reactions compared to males. The pervasiveness of this result across multiple domains suggests that general mechanisms might exist underlying females' unique adaptations. An understanding of such processes would enhance knowledge of female health and well-being. (shrink)

Extending Campbell's (1999) staying alive theory (SAT) beyond aggression, we reviewed evidence that females are more self-protective than males. Many commentators provided additional supporting data. Sex differences in life-history adaptations, in the optimal relation between survival and reproduction, and in the mechanisms underlying trade-offs involved with self-protection remain important topics with numerous opportunities for improved understanding.

This book presents an alternative to conventional ideas about the evolution of the human intellect.

"Intelligence" has long been considered to be a feature unique to human beings, giving us the capacity to imagine, to think, to deceive, to make complex connections between cause and effect, to devise elaborate stategies for solving problems. However, like all our other features, intelligence is a product of evolutionary change. Until recently, it was difficult to obtain evidence of this process from the frail testimony of a few bones and stone tools. It has become clear in the last 15 (...) years that the origins of human intelligence can be investigated by the comparative study of primates, our closest non-human relatives, giving strong impetus to the case for an "evolutionary psychology", the scientific study of the mind. (shrink)

To explain social learning without invoking the cognitively complex concept of imitation, many learning mechanisms have been proposed. Borrowing an idea used routinely in cognitive psychology, we argue that most of these alternatives can be subsumed under a single process, priming, in which input increases the activation of stored internal representations. Imitation itself has generally been seen as a This has diverted much research towards the all-or-none question of whether an animal can imitate, with disappointingly inconclusive results. In the great (...) apes, however, voluntary, learned behaviour is organized hierarchically. This means that imitation can occur at various levels, of which we single out two clearly distinct ones: the a rather detailed and linear specification of sequential acts, and the a broader description of subroutine structure and the hierarchical layout of a behavioural Program level imitation is a high-level, constructive mechanism, adapted for the efficient learning of complex skills and thus not evident in the simple manipulations used to test for imitation in the laboratory. As examples, we describe the food-preparation techniques of wild mountain gorillas and the imitative behaviour of orangutans undergoing to the wild. Representing and manipulating relations between objects seems to be one basic building block in their hierarchical programs. There is evidence that great apes suffer from a stricter capacity limit than humans in the hierarchical depth of planning. We re-interpret some chimpanzee behaviour previously described as and suggest that all great apes may be able to imitate at the program level. Action level imitation is seldom observed in great ape skill learning, and may have a largely social role, even in humans. (shrink)

Investigators of animal behavior since the eighteenth century have sought to make their work integral to the enterprises of natural history and/or the life sciences. In their efforts to do so, they have frequently based their claims of authority on the advantages offered by the special places where they have conducted their research. The zoo, the laboratory, and the field have been major settings for animal behavior studies. The issue of the relative advantages of these different sites has been a (...) persistent one in the history of animal behavior studies up to and including the work of the ethologists of the twentieth century. (shrink)

Berichte zur Wissenschaftsgeschichte, Volume 45, Issue 1-2, Page 189-199, June 2022.

Just as biologists have their favored places for doing research, so do historians. As someone who likes working in archives, the most surprising thing the present author ever found was a particular letter that had been written to him by the ethologist Niko Tinbergen—but that Tinbergen had never sent. The letter included a detailed critique of the intellectual style and conceptual shortcomings of Tinbergen’s career-long friend and colleague Konrad Lorenz. The present author first saw the letter 3 years after Tinbergen’s (...) death and 10 years after the letter was composed. Here we discuss the contents and historical context of that letter. (shrink)

In this bold work of broad scope and rich erudition, Richard W. Miller sets out to reorient the philosophy of science.

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According to Peter Singer, virtually all of us would be forced by adequate reflection on our own convictions to embrace a radical conclusion about giving. The following principle, he says, is “surely undeniable” -- at least once we reflect on secure convictions concerning rescue, as in his famous case of the drowning toddler.

Cognitive Science, Volume 46, Issue 6, June 2022.

Comparative analysis of the behavior of modern primates, in conjunction with an accurate phylogenetic tree of relatedness, has the power to chart the early history of human cognitive evolution. Adaptive cognitive changes along this path occurred, it is believed, in response to various forms of complexity; to some extent, theories that relate particular challenges to cognitive adaptations can also be tested against comparative data on primate ecology and behavior. This paper explains the procedures by which data are employed, and uses (...) the best currently available evidence to derive a proposal for some of the stages through which human cognition evolved, before the last common ancestor with a nonhuman, and the reasons that cognitive adaptations were favored in primate evolution. (shrink)

This dissertation interprets the lack of uniqueness in probability representations of agents' degrees of belief in the decision theory of Richard Jeffrey as a formal statement of an important epistemological problem: the underdetermination of our attributions of belief and desire to agents by the evidence of their observed behaviour. A solution is pursued through investigation of agents' attitudes to information of a conditional nature. ;As a first step, Jeffrey's theory is extended to agents' conditional attitudes of belief and desire (...) by introduction of a definition of conditional desirability. The second step is an analysis of agents' attitudes to conditionals. Following Adams it is argued that the probability of a conditional is the conditional probability of its consequent given the antecedent. Since numerous 'trivialization' results show that no proposition could be such that this were the case, it is proposed that conditionals express a variable proposition as a function of the context in which they are asserted. The consequent technical treatment of conditionals as proposition-valued functions of sets of possible worlds delivers Adams' thesis as a natural consequence without fear of trivialization. ;Conditionals are the underlying objects of the decision theory that is presented in the final chapter. A representation theorem is proven for preferences defined over sets of such conditionals satisfying certain closure conditions, where an agent is understood to prefer one conditional over another just in case she prefers that the former by true rather than the latter. The theorem establishes that a rational preference ranking of conditionals implies the existence of a unique probability function and a desirability function unique up to choice of scale, that agree with the preference ranking, and that these functions satisfy both the axioms of Jeffrey's decision calculus and Adams' thesis. The theorem is interpreted as saying that elicitation of an agent's choices amongst conditional options suffices to determine our attributions of belief and desire to them. (shrink)