Zombie apocalypses are very common themes in films, series, anime and games. Several reasons can lead to a zombie apocalypse, from a Sumatran monkey, exposure to radiation, extraterrestrial materials, mysticism / witchcraft, nanorobots, to the favorite of the media and Resident Evil fans, a biological factor (like a virus or a virus cure). Other productions simply do not mention (or did not notice if they mention) an origin, for example, Madrugada dos Mortos 1, 2, 3, … in these films the zombies appear out of nowhere and the story goes on.
However, let’s spoil some of the “fun” that would be living in a biological zombie apocalypse. Yes, this is a fun and hopeful theme for a lot of people who dream of going around with guns in hand, fighting zombie hordes and experiencing “Walking Dead” adventures (and of course, surviving).
To facilitate our analysis and give our zombies a chance, let’s assume in a super optimistic way, that the same energy of the body is used in the form of food by those who consume (we know that this is not true, but we will show that even if it were, the thing wouldn’t be good for zombies).
We will also consider that they eat only the meat of humans … because if they ate the meat of other animals, their “birth control” would be simplified, and if they eat vegetables or fungi, well, then it would start to become a joke (please, serve a plate of broccoli with capers and wine for this zombie).
We know that the world record for time without eating is from the Rio de Janeiro illusionist Ericson Leif, who spent 51 days on water. Thus, we can say that a person in ideal conditions and with sufficiently slow metabolism, can survive this period with an initial energy load of X calories (X being the number of calories that Ericson Leif had accumulated before fasting).
In an ultra optimistic way, we will say that all humans before becoming zombies, have these X calories available. And that after they turn into zombies, their metabolism works slowly enough to keep them active without eating any food for up to 51 days (Ericson Leif was at rest, but we’re giving zombies a chance, so we assume they can move freely in this same period).
So we arrived at our zombies and two representative representatives.
1. The zombie just “nibbles” another human being so that he becomes a zombie with an energy reserve very close to X;
2. The zombie eats another human’s flesh until its energy reserve returns to X.
BEHAVIOR ANALYSIS 1
In this context, a zombie does not eat to replenish its energy supply, but to proliferate the biological factor. Thus, each zombie will begin its journey with X of energy, and the zombie that bit the person will maintain their remaining Y of energy, without replacement.
The advantage for survivors in the face of this behavior is that we can determine how much time is left for the zombies by knowing the dates and numbers of victims in each attack. For example:
Day 0 – There were 10 zombies;
Day 14 – 3 people were attacked; (total 13 zombies)
Day 26 – 1 person was attacked; (total 14 zombies)
Day 38 – 2 people were attacked; (total 16 zombies)
Day 42 – 15 people were attacked; (total 31 zombies)
Day 51 – the 10 zombies of day 0 stopped working; (total 21 zombies)
Day 53 – 4 people were attacked; (total 25 zombies)
Day 65 – the 3 zombies of the 14th stopped working; (total 22 zombies)
In this perspective, in view of an intractable volume of zombies located in the same region, let’s assume that the entire population of the city of São Paulo became a zombie, that is, approximately 12,195,000 zombies, what to do?
A person walking lightly moves at 4 km / h. A zombie walking at this speed on highways and without interruptions, would travel 96 km a day, giving them a little more advantage, let’s round this distance to 100 km a day. In its 51 days of energy, it could cover up to 5,100 km. As zombies do not use GPS, do not orient themselves with maps and do not have a very clear purpose, we are dealing with a Markov chain, that is, they can move in any direction (to simplify, say north, south, east and west only). So, let’s say that each day a zombie would make a decision on which direction to go.
Simulating this behavior for a smaller number of zombies, 243,900 (only 2% of the total), we arrived that in its 51 days of walking, only 4,619 zombies (1.8% of the 243,900 analyzed) moved away from the origin at a distance of at least least 1,500 km.
Applying the result of this simulation to the context of São Paulo capital, we can estimate that 219,510 zombies will travel at a distance of at least 1,500 km.
Distributing these zombies to the perimeter of a circle with a radius of 1,500 km, we have 219,510 zombies to be distributed over 9,424 km. This gives us about 23 zombies every 1 km.
Thus, in cities located 1,500 km from São Paulo, such as Cuiabá (MT), which has approximately 26 km in its largest dimension, we could expect the appearance of approximately 600 zombies (it may seem like a lot, but remember that we are talking an initial outbreak in the range of 12 million).
BEHAVIOR ANALYSIS 2
In this context, the zombie encounters a human being, restores its energy to X, causing the new zombie to begin its “journey” with an energy reserve of less than 51 days. There is no difference between this behavior and the previous one, because if we consider that the zombies are physically equal, when the zombie with Y of remaining energy, finds a person, in the next moment we have a zombie with X of energy and a zombie with Y of energy. The situation is the same as that presented in behavior 1 less than a switch between zombies.
Thus, the best strategy to survive in the case of a conglomerate of biological zombies, is to move away from the epicenter, maintain strict surveillance at the borders and be patient until the number of zombies is easier to control.
The idea of experiencing a zombie pandemic is not uncommon in banal conversations between friends, as well as strategies for survival… but would we really follow the strategies of survival in a zombie pandemic, in which contacts need to be avoided as much as possible and any exit on the street to seek basic supplies can already be considered a potential risk?
Or would we do it like the movies and not believe what’s going on and try to pretend normalcy by promoting outings to find people without knowing if they were infected or not?
A biological pandemic requires removal of the epicenters, strict surveillance of borders, containment and treatment of patients, at the very least isolating them and a lot of, a lot of patience to stay well and healthy until the number of people infected with Coronavirus, I mean, zumbivirus is possible. be controlled (with vaccines, for example!).
I thank my friend Mago do Código, for vehemently insisting that a zombie apocalypse of the biological type as they happen in movies / series / games would be unsustainable, such discussions yielded the elaboration of this post 🙂
I also thank Professor Ana Arnt, for the post-conclusion, which connects the hypothetical scenario of a zombie apocalypse to the containment measures for general biological pandemics, such as the one in which we are living by the Coronavirus.