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Abstract

Evolutionary perspectives are part of any comprehensive explanation of leadership and, more generally, hierarchy formation in groups. This editorial describes contributions to a special issue on the theme of "The evolution and biology of leadership: A new synthesis", and we reach four main conclusions. First, leadership has been a powerful force in the biological and cultural evolution of human sociality. Humans have evolved a range of cognitive and behavioral mechanisms (adaptations) that facilitate leader-follower relations, including safeguards against overly dominant leaders. Second, how these adaptations interact with local ecological and cultural contexts produces cultural variation in leadership preferences, and in the structure of human organizations more broadly. Third, an evolutionary perspective creates consilience between the social and natural sciences, by integrating leadership theory from diverse fields such as biology, psychology, neuroscience, anthropology, economics, and political science. Fourth, evolutionary approaches – and specifically the collection of articles in this theme issue – produce and test novel hypotheses, such as regards (i) the critical role of leadership in cooperation, (ii) the importance of contextual factors in leader emergence and effectiveness, (iii) interactions between genetic and cultural influences on leadership, and (iv) obstacles and opportunities for women leaders.

Background and objectivesLow social status increases risk of disease due, in part, to the psychosocial stress that accompanies feeling subordinate or poor. Previous studies report that chronic stress and chronically elevated cortisol can impair cardiovascular and immune function. We test whether lower status is more benign in small-scale, relatively egalitarian societies, where leaders lack coercive authority and there is minimal material wealth to contest.MethodologyAmong Tsimane' forager-horticulturalists of lowland Bolivia, we compare informal political influence among men with urinary cortisol, immune activation (innate and acquired), and morbidity as assessed during routine medical exams.ResultsAfter controlling for potential confounds, we find that politically influential men have lower cortisol, and that this association is partly attributable to access to social support. Cortisol is positively associated with men's income, which may reflect chronic psychosocial stress from market involvement. Greater influence is also associated with lower probability of respiratory infection, which is a frequent source of morbidity among Tsimane'. Among men who lost influence over a 4-year period, cortisol and probability of respiratory infection were higher the greater the decline in influence.Conclusions and implicationsDeleterious effects of low status on health are not merely 'diseases of civilization' but may result from how (even subtle) status differences structure human behavior.

Background and objectivesLow social status increases risk of disease due, in part, to the psychosocial stress that accompanies feeling subordinate or poor. Previous studies report that chronic stress and chronically elevated cortisol can impair cardiovascular and immune function. We test whether lower status is more benign in small-scale, relatively egalitarian societies, where leaders lack coercive authority and there is minimal material wealth to contest.MethodologyAmong Tsimane' forager-horticulturalists of lowland Bolivia, we compare informal political influence among men with urinary cortisol, immune activation (innate and acquired), and morbidity as assessed during routine medical exams.ResultsAfter controlling for potential confounds, we find that politically influential men have lower cortisol, and that this association is partly attributable to access to social support. Cortisol is positively associated with men's income, which may reflect chronic psychosocial stress from market involvement. Greater influence is also associated with lower probability of respiratory infection, which is a frequent source of morbidity among Tsimane'. Among men who lost influence over a 4-year period, cortisol and probability of respiratory infection were higher the greater the decline in influence.Conclusions and implicationsDeleterious effects of low status on health are not merely 'diseases of civilization' but may result from how (even subtle) status differences structure human behavior.