Social insects point to non-genetic origins of societies
Social structures form through group dynamics, not trait selection
From her work studying social insects, Arizona State University biologist Jennifer Fewell believes that these remarkable animals suggest a an alternate cause behind the development of complex societies. In a viewpoint essay in the September 26 issue of the journal Science, Fewell argues that complex social structures like those seen in social insect communities can arise initially from the nature of group interactions -- the inherent dynamics of networks.
The ability of certain animals to form complex social systems -- particularly humans and social insects like bees, ants and termites -- is considered by many biologists to be one of the pinnacles of biological adaptation and complexity. Social organization allows organisms to share labor, to specialize in tasks and to coordinate efforts. Through organization, social animals accomplish remarkable things - they build colonies supporting millions of individuals, maintain multi-layered social systems, manage complex farming and food production systems, and build elaborate designs and constructions, from giant self-cooling termite towers to skyscrapers.
The development of social systems is often assumed to be driven by species modifications arrived at through natural selection. Social characteristics such as caste systems and complex behaviors have been thought to be traits programmed by genes, created through evolutionary processes. Though insect social systems are in many ways as complex as human societies, Fewell contends that the relative simplicity of the insects themselves argues against the systems being created solely by the evolutionary development of biocomplexity in the individual organisms.
"We look at human groups and we think we have these elaborate systems of interaction because we are elaborate beings, but when you look at an ant, you know that it is not an elaborate being," she said. ", When you see how elaborate their societies are, you realize that there is another answer to the question of how these arise. And if theres another answer for them, there might be another answer for us too."
Network dynamics, Fewell argues, can create organized social structures when relatively simple connections between various individuals in a group create patterns of behavior of increasing complexity, much the same way as relatively simple mathematical rules can create mathematical patterns of great intricacy.
"How do termites know how to build this huge chimney that allows a colony to thermoregulate?" Fewell asked. "The answer is that they dont - its an emergent property of simple interactions - one termite puts a piece of dirt there and the other termite comes along and smells that a termite put her piece of dirt there, so she does too, instead of somewhere else. At first its random and termites are putting their dirt in different places, but then one place becomes the dominant location and the structure goes from there."
In the same way, organized societies themselves can be created by patterns developed through simple interactions in a network of individuals.
"The patterns are things that we call emergent properties - colony-level behaviors or structures that can be explained by looking at interactions," Fewell said. "The one that I am most interested in is division of labor, in which different individuals perform different tasks and specialize on different activities.
"This happens, for example, when you put a group of students together. Give them an assignment and they start organizing -- somebody will start note-taking, and someone will structure the discussion, and someone will go up to the board, and someone will just sit there and let everyone else do the work. Similar division of labor happens in a social insect colony, though social insects are much simpler animals."
Though social networks are commonly thought of as evolutionary adaptations, Fewell turns this idea on its head by proposing that the network forms first, following the logic and pattern of group connections, then adaptation follows to strengthen the pattern. Social organization, seen in this light, is essentially an emergent property that comes from the networks geometry - a natural pattern to which organisms adapt.
"Social insects are interesting because you can follow them ,individually mark them and see the patterns form," she said. "Humans are affected by the same kinds of emerging properties. If you look at global patterns of social organization, you can see networks shaping what is going on. You are --in part-- what your social environment makes you."
James Hathaway | EurekAlert!