[Evolutionary biologist and super-soldier creator, Rajee Rajakumar, explores how real insects compare to StarCraft's Zerg.]
The massively popular game StarCraft tells the story of struggle among three alien races fighting for control over the galaxy. One of these races, the future humanoid Terran, seeks to colonize new planets; telepathic and cybernetic Protoss seek spiritual redemption; and hive-minded Zerg are out to consume, ravage, and assimilate anyone that is foolish enough to get in their way. Players select a race and then spend hours theory-crafting and refining their strategies to defeat their opponents. They carefully balance economic and military units in a futuristic sci-fi world. Our focus, however, will be on the in-game science fiction of the Zerg, with its unique life history and evolution.
In this piece, we take you through the most striking similarities between Zerg and their insect brethren in the wild. Suffice it to say the Zerg are heavily inspired by insect biology, but the extent to which evolution has generated such strikingly similar morphological diversity between the two is surprising. This is especially true when you consider their morphology (their looks), their social hierarchies, and their war tactics.
The Zerg are driven to evolve even in the harshest of environments, because, let's face it, planet Char is no cradle of life. They seek out apex predators on different worlds to assimilate and "absorb" their genomes. This empowers them with designer traits that can be used to make stronger and deadlier strains of Zerg units. This process is driven by "psionic" directives from the Overmind, a collective consciousness that controls the Zerg swarm. While not psychically capable, social insects on our own planet carry out similar directives to the Zerg through the use of pheromone trails secreted by colony members and queen(s). Similar to Zerg drones, worker castes in several social insects forage for food, build the nest and nurse larvae. The more developed insect societies have a more complex division of labor where subcastes and specialized jobs develop within a colony. This unique social structure has allowed these insects to cooperate to farm, hunt, build living bridges and even build rafts. How these traits develop over evolutionary time is a bit different than just plopping down an evolution chamber in StarCraft…
You require more minerals: Zerg drones mining gold and Pheidole vafra carrying a cookie crumb (Photo credit: Alex Wild).
In addition to division of labor, several social insects have been able to co-evolve interesting relationships with surrounding flora and fauna. While the Zerg have their own symbiotic parasites (i.e.: Mutalisk glade wurms, infestor neural parasites, and brood lord broodlings) several ants have formed interesting symbiotic/parasitic relationships as well. For example, several ants are known for protecting and herding honeydew secreting aphids/caterpillars. The Zerg infestor, however, employs a symbiotic parasite capable of seizing and controlling enemy units. While not used to the same effect, there are parasitic fungi that control the behavior of some species of ants. More specifically, Ophiocordyceps-infected ants unwillingly change their behavior to expose themselves to predators by hanging from leaves high above the safety of the ground. Under fungal control, these ants die and grow a tentacle-like stroma stalk with fruiting bodies (similar to the infestor neural parasite) to spread itself to its next host.
Ophiocordyceps OP. Mind controlling parasites used against ants and in StarCraft.
Zerg tactics range from overwhelming an opponent with a massive rush or finding balance between stronger units and a cheap frontline. In the insect world, the "Zerg rush" is a rather favored tactic in the appropriately-named army ants. This species exhibits "legionary behavior" and often forgoes scouting in exchange for quickly amassing a large expendable army that is capable of seizing one territory after another. It carries this out by switching between nomadic and stationary colony phases similar to roman legions.
Zerg rush (kekekekek) of a siege tank and army ant attack on a cricket (Photo credit: Alex Wild).
In addition to building large armies with expendable/cheap workers, the coup-de-grace comes in the form of the soldier caste. This strategy in army ants (and other species) relies heavily on cheap frontline workers to tire out adversaries followed by larger death-dealing soldiers (often by decapitation or dismemberment).
It should be noted that such an offensive strategy could be (hard) countered; Pheidole obstusospinosa evolved a unique tactic for defense against these raids. These ants evolved (in addition to their soldier caste) a supersoldier caste that has an enormous head, which they use to block entrances into their nest (Similar to a Greco-Roman phalanx). This strategy takes advantage of natural choke points, biding time before launching a counter attack.
Pheidole obtusospinosa prepare their defensive counter to fire ant raids by creating choke points outside their nest and follow up with a counter attack. Roaches getting a nice concave at the top of a ramp, keeping encroaching enemy units at bay. (Photo credit: Alex Yelich)
Since social insects (i.e.: ants, termites, bees, and some wasps) predominantly fight in close quarters; they have evolved a vast arsenal of weapons to wage war similar to certain Zerg melee and ranged attacks. Spraying acid among roaches and drones is common in the family ofHymenoptera (Wasps, Bees and Ants) while ensnaring enemies is a strategy in termite families that spew glue like latex from a gland on their forehead similar to that of infestors' fungal growth and queen's ensnare (from SC1). However, the most impressive war tactic seen in social insects is the employment of explosive suicide units, having evolved independently in both ants and termites. In ants, tree dwelling Camponotus saundersi are capable of exploding poison over nearby enemies just like the ever-so-friendly baneling. In termites, this strategy restricts itself toolder workers, which grow small blue backpacks that explode to ensnare and intoxicate nearby attackers. This unique, evolved trait restricts itself to eusocial animals where the division of labor allows certain individuals to be reproductive (a queen) or non-reproductive (soldiers/workers) and thus expendable...and "explodable"!
Baneling bust and Camponotus saundersi exploding on invaders. (Photo Credit: Mark Moffett)
Outside of the family of social insects, several similarities continue to exist between insects and their fictitious counterparts, the Zerg. Within the Zerg, thick carapace and armor are essential for defending and upgrading your army (as is the case with roaches and ultralisks). While there are no insects that can stop a bullet, the best example that comes to mind is the reinforced exoskeleton of armored crickets. This cricket developed thick chitinous armor (with spikes!) to defend against large predators and, like the roach, can vomit the contents of its stomach as a defense mechanism. Unlike the Zerg, however, this line of defense is backed up with its ability tohemorrhage its toxic haemolymph (its blood) to deter predators. Fun fact: when they do autohemorrhage, they have to clean themselves immediately for fear of cannibalization from other crickets!
Armored cricket next to a fearsome roach. (Photo Credit: Colin R. Owen)
In addition to armored roaches, the Ultralisk bears a colossal pair of tusk-like scythes used to shear enemy units causing splash damage and a wide area of effect. While not necessarily employed in the same fashion, stag beetles share similar antler plans. These antlers are pronounced in this species and are used as sexual displays, competing for mates, and for battling with other beetles.
Ultralisk and Stag beetles.
Lastly, what may seem analogous in form (but definitely not function) are the similarities between Zerg swarm host and the water bug. While not intimidating by name, this large predatory insect feeds mainly off of aquatic life (including baby turtles and snakes) and has one of the worst bites an insect can give. That being said, water bugs also win dad-of-the-year since males in this species invest a considerable amount of time and resources to carry the eggs of their young on their wings before hatching. Whereas Zerg swarm hosts send them to their deaths…
Swarm host next to a water bug (Photo Credit: Alex Wild)
StarCraft's Zerg are fascinating examples of science fiction in video games. While we don't know if Blizzard's team drew inspiration from these insects, seeing fictitious and real counterparts side-to-side could attest for some of their creative influences. Currently, insect behavior has drawn-in a surprising amount of attention from researchers interested in emergent behavior,swarm intelligence and models of artificial intelligence. Knowing the importance of tactics inStarCraft, it would be interesting to see how certain species would fare against some of the best pro gamers out there…