How a new fungi study could affect how we think about cognition

A species of wood-eating fungus didn’t need a brain to pass a cognitive test with flying colors, and researchers say this first-of-its-kind discovery could have broader implications for understanding consciousness and intelligence in a variety of life forms.
A team of researchers at Japan’s Tohoku University, led by Yu Fukasawa, associate professor in the Graduate School of Agricultural Science, set out to determine whether fungi could recognize shapes. Their study, published in the journal Fungal Ecology in October, found evidence that these bottom feeders possess memory and decision-making abilities despite not having a central nervous system.
READ MORE: These forest fungi are a bounty for Arizona mushroom hunters
Fungi grow by releasing spores that turn into long, filamentous threads that are thinner than a strand of human hair, explained Nicholas P. Money, a fungal biologist at Miami University in Oxford, Ohio, who was not involved with the study. The fungi then bundle together these microscopic filaments to form cords that allow them to branch out, similar to neural pathways in the brain, forming a larger colony known as the mycelium.
To set up their experiment, Fukasawa’s team incubated Phanerochaete velutina (a fungus that infects peach and nectarine trees) on small wooden blocks before transferring them to soil plates. In these soil plates, the fungi-laden blocks were arranged into two patterns, a circle and a cross, and left to decompose.
Several months later, the mycelial network had retained the same circle and cross patterns that it had initially been placed in. In particular, the mycelium that was placed in a circular pattern maintained the integrity of the shape by steering completely clear of the circle’s center rather than extending its cords through it.
Fungal mycelial networks connecting wood blocks arranged in circle (left) and cross (right) shapes. Photo by Yu Fukasawa et al.
The placement of the wood blocks had “quite profound effects upon the way that the fungus grows, and that suggests that the fungus is actually able to learn something about the pattern of food, the placement of food in its environment,” Money said.
Classical philosophers held the belief that the ability to form thoughts is a prerequisite of consciousness, exemplified by 17th-century philosopher René Descartes’ famed proclamation, “I think, therefore I am.” But the findings by Fukasawa’s team serve as a testament to the “extraordinary sensitivity” and “basic, primitive examples of consciousness” found in nature, Money said.
If the fungi lacked any cognition, they would have simply spread out along the blocks without consideration for patterns created by the researchers.
Instead, the fungal mycelium was able to recognize and relay information about its environment throughout its entire network in order to change its direction of growth accordingly.
Money described the findings as novel evidence of fungi’s simple “spatial memory,” a characteristic that researchers are increasingly discovering.
READ MORE: How studying arctic ground squirrels can help advance human brain health
This study is particularly exciting to Money because the field of fungal biology has in the last two to three years only started to recognize the sensitivity of fungi to their environment — a phenomenon he says has been critically overlooked.
“[Fukasawa’s team] is the first to actually figure out that the fungi are being really smart in the way that they explore the environment,” Money said.
Phanerochaete velutina in Commanster, Belgium. Photo via James Lindsey/ Wikimedia
The researchers are now looking for more clues into how exactly the mycelium communicates information about its surroundings throughout its network.
“We are studying the mechanisms of intelligent behavior of fungi and getting the evidence of their electrical signal transfer across mycelium,” Fukasawa told PBS News in an email.
New discoveries in the study of fungi cognition could lead to changes in the way we understand human cognition, Money and Fukasawa said.
Fukasawa said that one of the major takeaways from his team’s study is its challenge to prevailing ideology that consciousness is necessary for cognitive abilities like decision-making and memory.
“Our result on fungal intelligence may help people to notice that many part[s] of intelligent behavior of organisms can be achieved without brain and consciousness,” Fukasawa said.
Though Fukasawa clarified his team’s findings are currently limited to this one species of wood-decaying fungi, Money believes this study has potential for wider application and could pave the way for scientists to unlock a deeper understanding of our own neural abilities.
“When we look at the level of the individual cells, it’s not like human cells are any more complicated than the cells of any other organism on earth,” Money said. “Studying the sensitivity of individual cells may give us clues to how the human brain works in the future.”