Oh the things we learn when we skim through forensic medicine textbooks for a living. Apparently, there is a phenomenon called “postmortem luminescence.” And it should make zombie movies both less and more frightening.
Zombie movies get some things right. The “marbling” that we see on the skin of zombies is a real phenomenon. Without our immune system to keep them clean, our blood vessels are highways for bacteria. After we die, and our immune system stops working, the blood vessels fill up with bacteria, go dark, and marble the skin.
Still, there are missed opportunities in the genre. If we see zombies glowing in the dark, it’s usually because we’re watching a found footage film and seeing all-green “night vision.” Some zombies, however, after a certain point, should glow in the dark. Forensic books document postmortem luminescence, as an unusual, but natural part of the decomposition of the human body, especially when it’s left outside. Sometimes this luminescence is due to Armillaria mellea, otherwise known as the honey fungus. The name comes from the golden umbrella of the fungus, and the fact that the fungus is sticky when it gets wet. The body of the fungus doesn’t glow. Only the tiny, thread-like mycelia of the growing fungus glows. These fungus grows in decaying matter, often lighting up people’s woodpiles. They grow on the decaying matter of corpses as well.
Another common source of postmortem bioluminescence is Photobacterium fischeri, also known as Aliivibrio fischeri. This is a bacterium that’s found in salty, marine environments. It grows on decaying flesh, but also in living flesh. This is the bacterium that many animals, like the bobtail squid, use in their bioluminescence. They basically maintain dense colonies of the bacterium, which glows for them.
So here’s an aspect of zombie movies we aren’t considering. It’s true that not all zombies will glow (unless contamination with this bacteria is what turned them into zombies), but if groups of zombies are milling around, bumping into each other, the fungus and bacteria could spread. The bacterium is a quorum-sensing, meaning that when the colony becomes big enough it lights up. We could have movies full of monsters that suddenly glow in the dark.
Squid Image: Nick Hobgood
[Sources: Review of Forensic Medicine and Toxicology.]