Many animals – from locusts to fish – live in groups and swarm, but scientists aren’t sure why or how this behavior evolved.
In the Journal of the Royal Society Interface’s current issue, a multidisciplinary team of Michigan State University scientists has used a model system to show for the first time that predator confusion can make prey evolve swarming behavior.
Swarming allows groups of animals to accomplish tasks that they can’t do alone, such as defending themselves from a much larger predator.
“There are both costs and benefits to swarming and all other behaviors,” said Christoph Adami, MSU professor of microbiology and molecular genetics. “The benefits are discussed all the time. But the litmus test is whether a behavior evolves because of those benefits. Our model system shows that predator confusion was enough of a selection pressure to evolve swarming behavior in prey.”
Swarming actually makes the predators see many prey, said Randal Olson, computer science graduate student and lead author of the paper.
“In our computational model system, swarming evolved as a defense to exploit the predator confusion effect,” he said. “Rather than seeing just one or two prey when the predators attack, which is what happens when prey scatter, swarming makes the predators see many prey, which confuses them and allows more prey to survive.”
Because studying the evolution of swarming is extremely difficult to do in a real-world setting, the researchers used a computer model system where the predators and the prey continuously interacted. The system selected prey and predators that evolved survival-enhancing behaviors – either eating prey (the predators) or avoiding being eaten (the prey). Each experiment was replicated more than 100 times to make sure that the behavior evolved due to predator confusion and not just by chance.
Studying swarming and unlocking the secrets of why it evolved is a small first step toward understanding how human-level intelligence evolved in nature, a research goal of the team.
“We’re trying to learn about the problems that early animals faced that made intelligent behavior a favorable trait to evolve, with the goal of working our way up to understanding how early forms of intelligence evolved into the complex forms of adaptive, social and predictive intelligence humans are capable of,” Olson said. “Essentially, we’re trying to digitally reproduce the evolutionary path to human-level intelligence.”
Additional MSU researchers include Fred Dyer, zoology department chairperson; Arend Hintze, microbiology and molecular genetics post-doctoral researcher; and David Knoester, microbiology and molecular genetics National Science Foundation post-doctoral fellow.
All of the study’s authors are members of MSU’s BEACON Center for the Study of Evolution in Action.
The research was supported by the Paul G. Allen Family Foundation, the National Science Foundation, the MSU High Performance Computing Center and the MSU Institute for Cyber Enabled Research.