Maybe the zombie apocalypse starts with a virus or a supernatural event. Maybe the resulting zombies can move quickly but are more easily incapacitated, or maybe they’re slow and can be only taken out by a blow to the brain. Are these zombies cunning? Or are they awkward and uncoordinated, as I would argue any proper zombie must be?
Zombie lore may give us a lot of variety, but one thing every zombie scenario has in common is reanimation of the body after death. The body’s movements are slave to a brain that is no longer in control. But what do these differences matter? It’s all just science fictional horror movie fodder, right? Well, we’ve previously discussed scientific studies on how fast a zombie-like virus could spread, as well as neurobehavioral disorders in humans that leave their sufferers mimicking some key zombie traits. And it turns out, science has even more to say about zombies.
Zombie Carpenter Ants
In the Brazilian jungle, at a height of just about 10 inches off the ground, carpenter ants can be found with their jaws permanently locked on a leaf, frozen in a never-ending dance as an alien stalk grows through their head. These ants are the victims of ophiocordyceps unilateralis, also known as the zombie ant fungus.
The fungus first enters an ant’s bloodstream as single cells, but those cells soon begin copying themselves and, importantly, building connections so that those individual cells can share nutrients. These connections set the ophiocordyceps fungus apart from other fungi that simply kill off their host and eventually form networks that wrap around the ant’s muscles.
As the fungal network grows, the ant’s body succumbs to the fungus’s control. Interestingly, this network doesn’t appear to reach the ant’s brain. Entomologists are not sure whether the fungus releases chemicals that affect the ant’s brain from afar, effectively killing it as far as the ant is concerned, or if it takes a more sinister approach by leaving the ant’s brain alone to witness the remainder of the takeover but cutting off any muscle control, and thus the brain’s ability to stop it.
Either way, the ant is compelled to leave its colony and climb up a nearby plant to the precise height above the jungle floor where the humidity and temperature are optimal for the fungus to thrive. The ant is then forced to bite into a leaf to maintain its position, never to move again.
But the fungus isn’t done yet. With its host in perfect position, the fungal passenger forms a stalk that breaks through the ant’s head and produces spores that then rain down on the other ants below, grabbing more victims.
The zombie ant fungus isn’t alone in having the power to manipulate its host to best serve its own interest. For example, in an attempt to gain entry into host birds, a type of flatworm first invades the brains of California killifish causing them to exhibit “conspicuous swimming behaviors” that make them more vulnerable to attacks by those birds. But it does show a so far uniquely known ability to adapt over different climates.
As I mentioned, the Brazilian flavor of the fungus directs its host ants to hover around 25 centimeters off the jungle floor by biting onto a leaf. The whole stalk and spore creation process that spreads the fungus to other ants takes one to two months. However, in cooler climates like Japan and South Carolina, the ants are found instead clinging to twigs in trees several feet off the ground. In these climates the spreading of spores takes over a year and so the zombified ant must survive a winter season during which a leaf might fall to the ground but a twig will endure.
The scientists leading the study, including David Hughes and Raquel Gontijo de Loreto of Penn State, had a lot of help from a citizen scientist, Kim Fleming, who carefully documented the infestation of zombified ants that call her South Carolina property home. In a very unique claim to fame, the strain of fungus infecting her ants is now known as Ophiocordyceps kimflemingiae.
The change in climate that inspired this particular adaptation is expected to have happened in the distant past. But what does this mean for the rapidly changing climate we live in today? If the fungus is clever enough to alter its plans to accommodate the seasons, what adaptation will we see next?