Slime moulds could teach humans a thing or two about solving complex problems. But it’s what they can teach us about living communally that has broader implications for our future.
In the basement of a science lab at a campus in New England, alien-looking organisms are helping make crucial decisions that could determine the fate of humanity.
Far-fetched? Slime moulds has been tackling complex global issues since 2017 as scholars-in-residence at Hampshire College. The idea came from Jonathon Keats, an experimental philosopher who specialises in absurd “thought experiments”.
When you learn more about slime moulds (specifically Physarum polycephalum) however, the idea doesn’t seem so unbelievable. Although they don’t have any neurons or brains, they exhibit a capacity for learning and problem solving that can beat any human.
Slime moulds exist as single cells, but they can also combine infinitely with other cells (forming a superorganism) to achieve a common goal, usually to obtain food. Experiments are often created by spreading out oats, which slime moulds love to eat, in a petri dish, and mixing in obstacles, such as salt, caffeine or sunlight, which they tend to avoid. The slime moulds then work out the ideal routes to reach the oats, while steering clear of the obstacles, leaving vein-like structures along the way.
This innate ability to map out routes make slime moulds particularly useful in modelling efficient transit systems. In one experiment at the University of Hokkaido in Japan, slime moulds were able to recreate the Tokyo rail system by connecting to oats distributed in a pattern representing the cities around Tokyo. In just one day, they were able to accomplish something that took years for brilliant engineers to develop. Another study compared the motorway networks of 14 geographical areas to the routes established by slime moulds to determine which were the most efficient.
Observing how slime moulds navigate their way to their targets gives insight into more than just route efficiency. Other experiments have shown additional evidence of what can potentially be considered intelligence in slime moulds.
For instance, slime moulds were able solve a maze faster after fusing with another slime mould that had previously solved it, indicating that the latter was able to pass on their knowledge of the maze to the other cells. They were able to get used to impediments (in the form of caffeine or quinine) to reach their food, showing an ability to habituate to their environment. Slime moulds have also been found to anticipate future events, select the healthiest food, and “make tradeoffs between quality and risk”.
The fact that they do all these without a brain is forcing scientists to redefine their understanding of cognition, and is shedding some light into the origins and evolution of learning.
While there is debate over whether learning equates to intelligence, the fact that slime moulds can acquire, retain and transfer information—and act on them—show some form of rationality. How this rationality can apply to other biological entities could be something worth exploring, such as for example, how blood vessels grow to support tumours.
The applications go beyond the realm of science and engineering, as well.
Slime moulds have been used to help in making decisions with regard to legalising recreational drugs, environmental action and border policy, using the same oat and obstacle method done in other experiments. To see whether recreational drugs would lead to indulging in harder drugs, scientists used valerian root, which is highly addictive to slime moulds, to mimic drugs of varying concentration. They found that having an option of a less concentrated valerian root (similar to gateway drugs like marijuana) actually led slime moulds away from more concentrated, and thus more addicting, valerian root.
Perhaps the most intriguing quality about slime moulds is the fact that they consist of many but act as one. They act based on what’s best for the larger collective, even at the cost of individual cells. In a way, human societies, as they become more intertwined by technology, is becoming its own kind of superorganism. Unlike slime moulds however, we have yet to learn how to collectively act for our common good.
The absence of self-serving human bias, coupled with their efficiency in finding and distributing resources, enable slime moulds to make objective decisions that truly benefit all. By taking a page from how slime moulds behave, we humans may finally be able to ensure our survival. That might be exactly the point Keats wishes to get across with this thought experiment.
Resnick, Brian. “Trump Doesn’t Have a Science Adviser. This Slime Mold Is Available”, Vox, https://www.vox.com/science-and-health/2018/3/6/17072380/slime-mold-intelligence-hampshire-college.
Other related Sources:
Anzilotti, Eillie. “Let's Just Replace Our Government With Slime Molds (No, Really).” Fast Company, www.fastcompany.com/40536092/lets-just-replace-our-government-with-slime-molds-no-really.
Greenberg, Alissa. “Eight Smart Things Slime Molds Can Do without a Brain.” PBS, www.pbs.org/wgbh/nova/article/slime-mold-smart-brainless-cognition/.
Moskvitch, Katia. “Slime Molds Remember - but Do They Learn?” Quanta Magazine, www.quantamagazine.org/slime-molds-remember-but-do-they-learn-20180709/.
Sanders, Laura. “Slime Mold Grows Network Just Like Tokyo Rail System.” Wired, www.wired.com/2010/01/slime-mold-grows-network-just-like-tokyo-rail-system/.