A zombie is a “re-animated human corpse that feeds on living human flesh.”
Mostly they serve as fodder for popular entertainment. But an attack by real zombies would be anything but entertaining.
Four Canadian mathematicians who wrote “When Zombies Attack!: Mathematical Modeling of an Outbreak of Zombie Infection” warn,
“… if zombies arise, we must act quickly and decisively to eradicate them before they eradicate us.”
The scholars — Philip Munz, Ioan Hudea, Joe Imad, and Robert J. Smith — are from Carlton University and the University of Ottawa. They developed what is surprisingly “the first mathematical analysis of an outbreak of zombie infection.” The article will be published as Chapter 4 in the soon to be released book “Infectious Disease Modeling Research Progress.”
While obviously not realistic, their analysis “demonstrates… how modeling can respond to a wide variety of challenges in biology.”
The link between their work and biological attacks, pandemics, and related public health threats to the United States is an obvious one.
Why zombies matter to homeland security
The authors describe their basic model for zombie infection, discuss equilibria and stability issues, and then suggest conditions under which eradication of the zombie infection can occur. Based on their analysis, they conclude “only quick, aggressive attacks can stave off the doomsday scenario: the collapse of society as zombies overtake us all.”
The chapter starts by discussing the origins of zombies in the Afro-Caribbean spiritual belief system of “Vodou.” But the idea of the zombie dates back at least to the Middle Ages, and has appeared in the cultures of China, Japan, the Pacific, India, Persia, Arabia, and the Americas.
As the reader familiar with the concept may recall, zombies have no will of their own. Their heart and lungs and all their body functions operate at minimal levels, at least according to the traditional view.
Modern zombies are very different from voodoo and folklore zombies. Contemporary zombies are mindless monsters who do not feel pain and who have an immense appetite for flesh. They have a particular hunger for human brains (as the disturbing video at this link illustrates).
A zombie’s objective is to kill, eat or infect people. When a susceptible person is bitten by a zombie, it leaves an open wound contaminated by saliva, thus infecting the susceptible individual.
Informed speculation suggests the saliva disrupts oxygen flow to the brain. The lack of oxygen seems to be the specific mechanism that turns otherwise normal people into zombies.
Consequently in the few cases of zombie-ism that have been adjudicated by courts, authorities have concluded that because the zombies suffer from brain damage, they cannot be held accountable for the havoc they cause.
This clearly has hampered — but not eliminated — the search for effective prevention and mitigation strategies. Here is where the Canadian team makes its, probably inadvertent, but still foundational contribution to Homeland Security
Summary of the argument
In Section 2 of their paper, the authors outline the basic model describing how — like a deadly virus — zombies grow and increase (please see Figure 1, where S are those who are susceptible to attack, Z are the zombies, and R are those who have been “removed” but who can return to the arena after an encounter with Z). The authors correctly note their model is “slightly more complicated than the basic SIR [susceptible, infected, and removed] models that usually characterize infectious diseases.”
The authors discouragingly find that from the perspective of their basic model, “In a short outbreak, zombies will likely infect everyone.”
The remainder of the article discusses strategies available for dealing with a zombie attack:
- Section 3 (The basic model, with time latency),
- Section 4 (The model, plus quarantine),
- Section 5 (The model incorporating a cure for zombie-ism), and
- Section 6 (Rapid and aggressively escalated destruction of zombies)
The interested reader can view the full analysis of each variation by downloading the original paper here. I found the math to be slightly impenetrable (see the figure below for an example). But the authors’ conclusions are starkly clear:
“An outbreak of zombies infecting humans is likely to be disastrous, unless extremely aggressive tactics are employed against the undead. While aggressive quarantine may eradicate the infection, this is unlikely to happen in practice. A cure would only result in some humans surviving the outbreak, although they will still coexist with zombies. Only sufficiently frequent attacks, with increasing force, will result in eradication, assuming the available resources can be mustered in time.”
The authors acknowledge the key difference between their model and traditional views of infectious disease is in their model “the dead can come back to life.”
They admit their scenario is unrealistic if taken literally, “but possible real-life applications [of their model] may include allegiance to political parties,… diseases with a dormant infection,” and — one might add — a zombie-like commitment to certain beliefs, attitudes, policies, and organizational arrangements.
The article ends by summarizing the strategic implications of the analysis:
“A zombie outbreak is likely to lead to the collapse of civilization, unless it is dealt with quickly. While aggressive quarantine may contain the epidemic, or a cure may lead to coexistence of humans and zombies, the most affective way to contain the rise of the undead is to hit hard and hit often. As seen in the movies, it is imperative that zombies are dealt with quickly, or else we are all in a great deal of trouble.”