Monday, June 12, 2017

The Evolution of Mammalian Leadership

If Aristotle was right in claiming that political animals achieve the coordination and collective action of individuals for shared ends, and that leaders can help them solve coordination  and collective action problems, then the comparative study of political animals might illuminate the evolutionary roots of leadership, including human leadership.

Although human political leadership has been long studied by political philosophers and social scientists, only in the last few decades have some biologists studied political leadership among nonhuman animals, and only very recently have some scholars started to combine these two areas of research to develop a general evolutionary science of animal leadership (King, Johnson, and van Vugt 2009; Smith et al. 2016; van Vugt and Ahuja 2011).  I am beginning to think about how this might provide an evolutionary explanation for Machiavellian leadership among chimpanzees and human beings.

MAMMALIAN LEADERSHIP IN FORAGING SOCIETIES
Jennifer Smith and her colleagues (2016) have provided a general synthesis of the research on animal leadership from an evolutionary perspective.  They examine and compare the patterns of leadership in eight small-scale human societies (including the Ache, the Cheyenne, and the Inuit) and eight nonhuman mammalian societies (including elephants, dolphins, and chimpanzees). 

They review the theoretical models and empirical studies of leadership in four domains: movement, food acquisition, within-group conflict mediation, and between-group interactions (peaceful or violent). 

They look for patterns of variation in leadership in five dimensions: distribution (across individuals), emergence (achieved versus inherited), power, relative payoff to leadership, and generality (across domains). 

They do ratings (from 1 to 5) for each of these five dimensions in each of the four domains.  So, for example, in within-group conflict resolution, the distribution of leadership could be rated at 5, if one individual usually leads in resolving conflicts, or, at the other extreme, at 1, if all adults are autonomous in acting to resolve conflicts.

In comparing the nonhuman and human societies, they found remarkable similarities in the patterns of leadership in the five dimensions.  First, in the distribution of leadership, they found that for most societies, human and nonhuman, leadership was moderately shared in most domains.  Nevertheless, leadership was notably more concentrated (less shared) in the domains of conflict resolution and between-group interactions.  Even in generally egalitarian foraging human societies, where adult individuals have a lot of autonomy, there is some leadership, particularly with individuals who have the reputation for being good leaders in resolving conflicts within the group and in dealing with outside groups.

Second, in the emergence of leadership, most of the 16 societies studied show  mostly achieved rather than ascribed leadership status--that is, individuals become leaders mostly through their own actions or qualities rather than through some inherited status.  The two exceptional cases are spotted hyenas and the Nootka (American Northwest Coast Indians), with leadership that is highly inherited in all domains.

Third, in the power of leadership, leaders in small-scale human societies are generally less powerful than leaders in the nonhuman mammalian societies.  That explains why human foraging bands are generally identified as egalitarian, in contrast to the hierarchical inequality of chiefdoms and state societies.  But even so, leaders in human foraging bands are more powerful in the domains of within-group conflict resolution and between-group interactions.

This suggests that mammalian leadership might have evolved to foster cooperation by solving the problem of collective action that is undermined by conflict and free-riders.  One solution to this problem is costly punishment of cheaters, and so a leader might become the sole arbiter of punishment and thus solve this collective action problem.  In fact, alpha male primates play a large role in peacemaking and conflict resolution (de Waal 1982, 1989; Flack et al. 2006; King, Johnson, and van Vugt 2009; O'Gorman, Heinrich, and van Vugt 2009).  Leaders and followers could then be in a mutually beneficial reciprocal relationship: leaders provide the service of costly punishment of cheaters in exchange for prestige accorded them by their followers (Price and van Vugt 2014).

Fourth, in the relative benefit of leadership, Smith and her colleagues see that across most of the 16 societies they studied, the fitness related payoffs for leaders are generally equal to or only slightly better than the payoffs for their followers.  Of course, this would not be true for the large, highly stratified human societies that arose after the rise of agrarian states.

Finally, in considering the generality of leadership, leadership is somewhat more generalized in nonhuman mammalian societies than in small-scale human societies.  In societies with strong dominance hierarchies--such as capuchin monkeys, meerkats, and hyenas--high-ranking individuals generally fill most leadership roles.

This all shows the continuity between nonhuman and human political leadership.  But, obviously, we must also explain the discontinuity, in that human leaders can manage collective action that far exceeds in scale and complexity the collective action of nonhuman animal societies.  This human difference arises from some distinctively human cognitive capacities for symbolism, syntactic language, and shared intentionality, which allow leaders to organize societies for collective action through rhetorical persuasion and institutional norms.  This has been the subject of previous posts here, here., and here.

Smith and her colleagues have looked only at human leadership in small-scale societies, so we must still explain leadership in large agrarian states that have often been despotic, and in modern liberal regimes that are more open and less despotic, although they allow inequality of status, wealth, and power.  This  has come up in various posts here, here, here, here, here, here, and here.


REFERENCES

de Waal, Frans. 1982. Chimpanzee Politics. New York: Harper & Row.

de Waal, Frans. 1989. Peacemaking Among Primates. Cambridge: Harvard University Press.

Flack, J. C., M. Girvan, Frans de Waal, and D. C. Grakauer. "Policing Stabilizes Construction of Social Niches in Primates." Nature 439: 426-429.

King, Andrew J., Dominic Johnson, and Mark van Vugt. 2009. "The Origins and Evolution of Leadership." Current Biology 19: R911-R916.

O'Gorman, R., J. Heinrich, and Mark van Vugt. 2009. "Constraining Free Riding in Public Goods Games: Designated Solitary Punishers Can Sustain Human Cooperation." Proceedings of the Royal Society B: Biological Sciences 276: 323-329.

Price, M. E., and Mark van Vugt. 2014. "The Evolution of Leader-Follower Reciprocity: The Theory of Service-for-Prestige." Frontiers in Human Neuroscience 8: 1-17.

Smith, Jennifer, Sergey Gavrilets, Monique Borgerhoff Mulder, Paul L. Hooper, Clare El Mouden, Daniel Nettle, Christoph Hauert, Kim Hill, Susan Perry, Anne E. Pusey, Mark van Vugt, and Eric Alden Smith. 2016. "Leadership in Mammalian Societies: Emergence, Distribution, Power, and Payoff." Trends in Ecology & Evolution 31: 54-66.

van Vugt, Mark, and Anjana Ahuja. 2011. Naturally Selected: The Evolutionary Science of Leadership. New York: HarperCollins.

2 comments:

Roger Sweeny said...

This suggests that mammalian leadership might have evolved to foster cooperation by solving the problem of collective action that is undermined by conflict and free-riders.

That sounds a lot like Morris B. Hoffman's The Punisher's Brain: The Evolution of Judge and Jury (2014), a very good book that has gotten nowhere near the notice it deserves (perhaps because the subtitle makes it seem more narrow than it is).

Larry Arnhart said...

I agree. I wrote a post on Hoffman's book on 4/3/15.