Consensus among the pigeons

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Consensus among the pigeons

Human beings contrive to be generally peaceful while living in associations, such as modern cities, far larger than any groups known among other mammals. How a collective spirit of altruism evolved despite evident genetic advantages in cheating or violence was a matter of ground-breaking research, 1963-1981, by William Hamilton, Robert Trivers and Robert Axelrod. But we’re not so good at the politics, are we? Ever since cities and taxes were invented, power in the hands of emperors, dictators, military rulers and other kleptocratic governments has all too often been the norm. News from Budapest suggests that we may have something to learn from pigeons.

The story about “Altruism and Aggression” in Magic Universe begins with Peter Kropotkin, a prince of Russia who turned anarchist and fetched up in the UK, which was humming with scientific ideas. In his book Mutual Aid: A Factor of Evolution (1902) Kropotkin cited, in the Darwinian spirit, hints of altruistic animal behaviour that he observed during travels in the Siberian wilderness. His thesis was that people in general are inherently virtuous and helpful to one another, and so don’t need to be disciplined by political masters.

Backpacking pigeon. Photo: Z. Ákos

Helped by pigeon fanciers, the team led by Tamás Vicsek of Eötvös Loránd University had light-weight GPS (satnav) backpacks attached to homing pigeons. They could then track the birds’ interactions second-by-second as they flew in a flock and maintained their amazingly efficient consensus about which way to go next, whether on homing flights or spontaneously flying together near home.

“It is the first study demonstrating hierarchical decision-making in a group of free-flying birds,” Vicsek remarks in the online NatureNews. But comments by the team in the published report make clear that it’s no inflexible pecking-order dictatorship.

Individuals’ roles are manifested in a dynamically changing manner … with the leading role of a given bird fluctuating over time. … This is a sophisticated system that may, from an evolutionary perspective, bring benefits to individual group members over, for example, a single-leader scenario, or an ancestrally (presumably) egalitarian collective.”

Two minutes' flight by ten pigeons tracked by GPS in Hungary. Each letter denotes an individual in the flock. Scale in metres. Fig. 2a in Máté Nagy et. al, Nature 2010

Vicsek elaborates on this theme to Rachel Ehrenberg of ScienceNews. “These pigeons know each other. They know which is the smartest. The fastest bird will even follow the slower one who knows the way home the best,” says Vicsek. Videos of the birds’ positions during flight showed that if the best navigator moves a little to the left, it takes about a third of a second for other birds to do the same. But if the least savvy bird makes a move “the others don’t care,” Vicsek says.

It’s remarkably commonsensical by human standards, with none of the authoritarian or violent behaviour often found in hierarchies, animal or human. Will a century of effort to validate social injustice as the “survival of the fittest” now flutter broken-winged to the ground? Be that as it may, Prince Kropotkin would surely have approved the style of the pigeons’ mutual aid in the matter of navigation.


M. Nagy, Z. Ákos, D. Biro, & T. Vicsek, Nature 464, pp. 890-893, 2010

NatureNews item 7 April 2010

ScienceNews item 7 April 2010

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