Evolution Explains Computer Viruses and Zombie Animals

Lead photo: the green jewel wasp in action. Via.

There’s been a lot of talk about the United States’ drone fleet being compromised by a virus. That talk is quite deserved as we still don’t really know what effects the virus may have on our unmanned arbiters of death.

The Stuxnet worm, another virus made famous earlier this year, was designed to attack Iranian uranium enrichment facilities and in the process infected scads of industrial and infrastructure facilities. It’s a scary thought if you choose to think about it: flying weapons, nuclear fuel and major industries possibly being controlled against their will by some infiltrating agent.

Some say it’s all proof that mankind’s intelligence and appetite for destruction will eventually produce the apocalypse, right? I mean, nothing else in nature could ever be so sinister as to sneak inside an entity to surreptitiously grab control, right?

Oh, give me a break. That type of sneaky, underhanded shit is happening in nature all the time.

Computer viruses are named as such because of how they propagate: they weasel their way into a system, replicate and spread, just like biological viruses. But the actual effects they have – grabbing the reins to that system’s brain – are more similar to the work of some particularly-nasty, zombie-creating parasites.

It’s an unfortunate myth of zombie movies that viruses will turn the world into legions of brain-suckers. Parasites are a vastly more common source of zombification in nature. Take, in a classic example, the orb-weaving spider of the Plesiometa genus in Costa Rica. Parasitic Hymenoepimecis wasps are big fans of the orb-weavers; such big fans, in fact, that a wasp will glue an egg to the spider’s stomach for safekeeping.

This video “Parasitoids in action, spiders under command” about Hymenoepimecis is from Brazil. The graphics are cool even if you don’t speak Portuguese.

Once the egg hatches, the larva goes to town feeding on the spider’s fluids until it grows into its second life stage. At that point, the real weird stuff happens: the larva injects a chemical (or series of them) into the spider and effectively takes control of the creature. As William Eberhard writes in The Journal of Arachnology:

The larva induces the spider to perform highly stereotyped construction behavior and build an otherwise unique ”cocoon web” that is particularly well designed to support the wasp larva’s cocoon. Cocoon web construction behavior is nearly identical with the early steps in one subroutine of normal orb construction, and is repeated over and over. Usually all other normal orb construction behavior patterns are completely or nearly completely repressed.

Another wasp, the green jewel wasp, carries out a more cringe-worthy version of the same tactic on cockroaches. The wasp actually injects a cockroach with a venom that blocks octopamine, a brain chemical that keeps the cockroach awake and moving around. After effectively paralyzing its victim, the wasp then injects its own larvae inside the froze roach. With the roach more or less unmoving but still alive, the larvae are guaranteed a fresh meal as they slowly eat their way out over the course of a week.

Forcing a creature to make a home for you before you kill and eat it seems pretty dastardly, but hey, that’s life. Possibly more rude is the spiny-headed worm, which causes the cute little isopods (AKA pill bugs or roly-polys) you played with as a kid to commit suicide. Isopods normally hide under rocks and such to be safe, but once infected by spiny-headed worms their behavior changes. The worms controlling their brains make them wander out into the open and sit there like a tasty little snack.

Eventually they get eaten by the European starling, a lovely spotted bird. The worm’s life cycle continues within the bird, which eventually drops poop that’s laced with worm eggs. The isopods, who like to dine on bird poop, also eat the eggs, and the circle continues.

Disco snails are zombie snails.

In another cycle that features bird turds, the poor, sedate-looking amber snail gets turned into a blinking, flashing party snail by flat worms of the Leucochloridium paradoxum species. Like with the spiny-headed worm, this flat worm matures within a bird’s stomach and lays eggs into its digestive tract, which consequently are excreted. After an amber snail eats the eggs, the larvae eventually hatch and migrate into the snail’s eye stalks. These stalks swell up to gargantuan size with a larva inside that wiggles around to flash all kinds of crazy stripes and colors, which serve as nothing more than a giant ‘EAT ME’ sign for birds, who then become infected themselves.

So does this mean that we should be scared out of our wits? I mean, zombie animals abound, and there is that whole cat scratch fever thing to worry about. Now we’ve got zombie drones and zombie nuclear fuel refineries. If you want it to, it sounds like the making for the end of the world. Yet right now there’s no clear outcome. We’re not even sure if the drone virus is even ‘bad’ – although that does discount the fact that drones shouldn’t be getting infected in the first place. It comes down to this: zombie computers exist, and on the face that’s pretty disconcerting, just as finding the first zombie animal probably was. But until research provides some more concrete answers, there’s no sense getting too stressed. Unless, of course, drones start laying their eggs in your brain.

Evolution Explains is a periodical investigation into the human-animal (humanimal?) condition through the powerful scientific lenses of ecology and evolution. Previously on Evolution Explains: Free Public Wi-Fi and Why Plants Make Drugs.

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