Aggression, rank and power: why hens (and other animals) do not always peck according to their strength

Thorlief Schjelderup-Ebbe's seminal paper on the ‘pecking’ order of chickens inspired numerous ethologists to research and debate the phenomenon of dominance. The expansion of dominance to the broader concept of power facilitated disentangling aggression, strength, rank and power. Aggression is only one means of coercing other individuals, and can sometimes highlight a lack of power. The fitness advantages of aggression may only outweigh the costs during periods of uncertainty. Effective instruments of power also include incentives and refusals to act. Moreover, the stability of the power relationship might vary with the instruments used if different means of power vary in the number and types of outcomes achieved, as well as the speed of accomplishing those outcomes. In well-established relationships, actions or physiological responses in the subordinate individual may even be the only indicator of a power differential. A focus on strength, aggression and fighting provides an incomplete understanding of the power landscape that individuals actually experience. Multiple methods for constructing hierarchies exist but greater attention to the implications of the types of data used in these constructions is needed. Many shifts in our understanding of power were foreshadowed in Schjelderup-Ebbe's discussion about deviations from the linear hierarchy in chickens. This article is part of the theme issue ‘The centennial of the pecking order: current state and future prospects for the study of dominance hierarchies’.

Tricks of Transference: Oka Asajirō (1868–1944) on Laissez-faire Capitalism

ArgumentContrary to common portrayals of social Darwinism as a transference of laissez-faire values, the widely read evolutionism of Japan's foremost Darwinist of the early twentieth-century, Oka Asajirō (1868–1944), reflects a statist outlook that regards capitalism as the beginning of the nation's degeneration. The evolutionary theory of orthogenesis that Oka employed in his 1910 essay, “The Future of Humankind,” links him to a pre-Darwinian idealist tradition that depicted the state as an organism that develops through life-cycle stages. For Oka, laissez-faire capitalism marked the moment when the state began to decline toward extinction due to the orthogenetic overdevelopment of hitherto subordinate individual egos. Because conservative bureaucrat-intellectuals had been drawing upon this same organicist-developmental tradition since the 1880s in an attempt to forestall the social ills of industrialism, Oka's call for statist measures, including eugenics, to lessen and delay the atomizing, enervating, and corrupting influence of capitalism articulated the political vision of officialdom. Statist evolutionism, not social Darwinism, might be the term that best describes Oka's approach.

Aspects of Social-Behavior and Dominance in Male Rainbow Skinks, Carlia-Rostralis

A laboratory study was conducted to observe patterns of social behaviour of males of the sexually dimorphic rainbow skink, Carlia rostralis. Animals were observed alone or in matched pairs, both as residents and non-residents of the testing cage. Behavioural patterns observed included active, aggressive, submissive, assertive, exploratory and escape categories of acts. These patterns of behaviour varied in social contexts. Active behaviour increased significantly when males were paired. Of the paired encounters, 60% had neutral outcomes in which no dominant/subordinate individual could be determined. When dominance/subordinance interactions occurred they were found to be expressed in a linear hierarchy. Dominance was positively correlated with male snout-vent length. Dominance of males was absolute and did not depend on residence status. These observations of social behaviour in the laboratory, together with preliminary observations of behaviour of this species in the field, suggest that Carlia rostralis exhibits different patterns of social behaviour from that observed in other scincid lizards.