When we think of networks, we think of humans and the cables we’ve run around the world to connect our species. Figuring out how to move electrons has transformed human society, but we are not the only species on earth that lives in a wired world.
A few years ago, microbiologist Gemma Reguera of Michigan State University reported that a certain type of bacteria could use rust to grow electrically conductive appendages. Shortly thereafter, my lab showed that many more bacterial species also had the ability to grow nanowires. The oxygen-making cyanobacteria that “invented” photosynthesis produce conductive nanowires in response to limited amounts of carbon dioxide. Heat-loving, methane-producing consortia of microorganisms even appear to produce nanowires that connect organisms from separate domains of life.
We are slowly, yet steadily, realizing that many (perhaps most?) bacteria produce nanowires. And the extracellular structures connecting bacterial cells into complex integrated communities create a pattern that looks suspiciously like a neural network.