As Physarum polycephalum, which is a yellow slime mold, searched for oat flakes, a biological process occurred. In a study from 2010 that appeared in Science, researchers positioned oat flakes on a petri dish to correspond with the locations of cities near Tokyo. They placed the mold at the central point of the capital and observed its growth for approximately twenty four hours. Physarum is a yellow organism that often moves across rotting wood following rainfall. It lacks a brain a nervous system and neurons. To describe the structure it created, many biologists consider this a significant experiment in the field.
At the start the mold expanded in all directions because it does not possess a central plan. It created a thick and complex web across the surface of the dish. There was no visible pattern or direction toward a specific goal - but after some time, the behavior changed. When routes transported more nutrients, those paths became thicker. If paths were weak, they became thinner and eventually vanished. After many hours the result was a simplified network that linked the food sources - this structure maintained a balance between the total distance of the paths and the speed of transport.
Tokyo Had No Idea
When the researchers looked at this final network alongside the railway system of Tokyo, the two structures were similar. For Mark Fricker of the University of Oxford, who is a co author, the mold had "no central brain or indeed any awareness of the overall problem it is trying to solve, but manages to produce a structure with similar properties to the real rail network" And he also observed that there was "a remarkable degree of overlap between the two systems"
The researchers chose their words with precision when they stated that the patterns are "comparable" rather than identical. By following simple local rules, the mold functions without conscious planning or an understanding of the city of Tokyo and its rail network. It operates - strengthening connections that are successful, reducing those that are not and moving in response to the chemical signals present in each tendril. There are no neurons or central coordination points in the organism plus it lacks awareness regarding the larger pattern that it creates.
As the environmental constraints are similar for both entities, the results are considered significant. In the region of Tokyo, there are mountains, lakes and high population densities that determine the necessary flow of transport. Both an organism that searches for food and engineers who plan transit networks respond to the same geographic features.
Rules Into Real Infrastructure
To go beyond simple observation, the researchers translated the behavior of the mold into a mathematical model. This model mimics the biological process where connections are laid down broadly before the system reinforces the that carry heavy traffic but also removes the others. By adjusting the parameters within the model, users can push the process toward higher levels of efficiency or resilience based on the requirements of the network. With those findings, the work now influences research into adaptive routing, sensor networks and communication systems that reconfigure themselves when conditions change.
What the Mold Got Wrong
In this context it is necessary to note a specific limitation. The network that the slime mold formed is not the same as the rail system in Tokyo. Because human engineers included extra paths for backup purposes, some data indicates that the rail network handles damage or errors better than the network from the mold - this result is not a failure of the slime mold, as the two systems are for different goals. To solve the problem, nature produced one functional arrangement. By comparison engineers created a different arrangement based on separate requirements. If one considers the critiques, this event is one particular instance rather than evidence that slime molds are able to replicate every transportation system that exists. And a result that is simple and effective in one case is not a law that applies to everything - but the experiment is valid because it shows that local biological actions create structures that are functional on a larger scale.
Memory Without a Mind
As research continues, the findings are more unusual - it appears that Physarum possesses a system for data retention even though it lacks a brain. When the organism travels, it produces a trail of slime and usually avoids that path at a later time. By using the path it traveled previously, the organism guides its future movement. If researchers hide or cover that trail during tests, the organism is more likely to move without a clear direction, return to previous areas or stop before it reaches the target. On some occasions, the information that functions like a memory is not inside the cell. It is located on the external surroundings.
Systems do not always require thought to display intelligence. In some cases this quality arises from physical structure, the return of information and the movement of signals through a network. As a creature lacks eyes, a brain and a nervous system, it is still able to create an output that appears intentional - this occurs if the small scale rules that the organism follows align with the requirements of the surrounding environment.