http://www.newscientist.com/news/news.jsp?id=ns99993248

Democracy beats despotism in the animal world

The New Scientist, 19:00 08 January 03

James Randerson

Democracy wins hands down over despotism when it comes to making choices in an animal group, according to a new theoretical model of collective decisions.

“It tells us that democratic behaviour is not unique to humans and is probably widespread,” says Tim Roper at University of Sussex, UK, who carried out the work with his colleague L Conradt.

In most vertebrate groups, such as apes and deer, there is a clear hierarchy with one dominant individual who dominates potential rivals. Roper says that many researchers have simply assumed that the dictator also makes decisions such as where to go and how long to feed for.

But although the dominant male, for example, might exclude challengers for breeding rights, he does not necessarily get his way about everything.

On the hoof

Roper and Conradt based their model on red deer. These animals spend most of their time either lying down ruminating or feeding on the hoof. But not every individual will want to move from one to the other at the same time.

In the democratic version of the model, Roper and Conradt allowed each virtual deer to vote, by standing up when it has finished ruminating. When half the deer have stood up, the group moves off. In the despotic version, one individual makes the decision based on its preference with the rest forced to follow suit.

The collective costs to all the individuals were greater under despotism because the dominant's decisions tend to be more extreme. But, more surprisingly, democracy was favoured even if the dominant individual is an experienced individual that makes fewer errors in its decisions than the subordinates.

However, Gilbert Roberts, an animal behaviour researcher at the University of Newcastle, UK, describes the model's message as little more than “intuitive”. He points out that group decision-making is probably much more complicated because individuals change their decisions based on the actions of others, but the model does not take account of this.

Polling cards

Implementing an efficient democracy can be a complex task, as the last US presidential election demonstrated. But Roper is adamant that collective decisions do not necessarily require polling cards or even a sophisticated brain.

In the case of real red deer, the animals do indeed vote with their feet by standing up. Likewise, in groups of African buffalo, individuals decide where to go by pointing in their preferred direction. The group takes the average and heads that way.

Anna Dornhaus, who researches ant behaviour at Bristol University, UK, notes that research on the collective decisions of social insects is much more advanced. “But researchers have not assumed that a huge cognitive ability is necessary,” she says.

She does not think the model will tell us much about the merits of democracy in human society, but she says it challenges the popular perception that the natural world is run by dominance and violence. “Democracy is not something that humanity invented,” she adds.

Journal reference: Nature (vol 421, p 155)

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