What brainless slime mold can teach us about making better decisions

Nov 30, 2015

There is a mindless, senseless yellow-tinted blob of an organism that lives on the forest floor. It’s called slime mold and even though it lacks a brain, it can be relied upon to make a healthy decision more often than most humans. 

“It lives on the forest floor, and it loves moisture and darkness. And it just meanders around looking for food,” Science Friday video producer Luke Groskin. “It has no eyes, and it can only feel for food. So how does it make a decision? How does that creature decide, ‘Oh, it's time to go over here. It's time to go over there.'”

A team of scientists at the New Jersey Institute of Technology wondered about the decision-making abilities of slime mold. They conducted a series of experiments wherein they placed slime mold on a track between two different piles of food. Then they watched as the slime mold moved toward the bigger pile of food a full 80 percent of the time. 

“The slime mold has no eyes. It has no sensory equipment, but yet it makes the right decision 80 percent of the time,” Groskin says. “It's absolutely way, way better than anything we could do.”

Simon Garnier at the New Jersey Institute of Technology is also studying the decision-making and organizational behavior of swarms of ants. In one of his experiments with ants, Garnier set up a series of gaps or roadblocks for ants, and time-lapse footage of the ants showed them building a live bridge or ladder to circumnavigate the gap.

“Every time I’m in traffic, it’s an occasion for me to observe the behavior of the other people and try to understand why we are so bad at organizing our traffic when ants, for instance, are so efficient at it,” Garnier says.

The ants have very tiny brains, and no leader or boss telling them to do something. Instead, scientists think, the ants are programmed to do things on certain cues. When, for example, an ant is stepped on, that may be the cue for them to just stop. When this cue is repeated over and over again, they are able to build a living, swarming, moving bridge to allow other ants to climb on top of them.

“The next step is to turn these behaviors into equations and computer models,” Garnier says. 

Garnier is hoping to use slime mold and ants as a model to learn more about criminal behavior or car traffic. He wants to use his research to design systems, roads, robots, maybe even cities that can achieve the same efficiency as, for example, slime mold.

 “Our work," Garnier says, "Is all about how a large-scale organization emerges from the actions of a lot of different individuals.”

This article is based on an interview that aired on PRI's Science Friday.