Credit: Revenant Magazine
The origin of zombies (Genus: Zumbi) is well understood today, but this wasn't the case when they were first discovered in the early 1800s. Charles Darwin was the first to recognize that zombie "reproduction" results in a process of descent with modification in a way analogous to that of non-undead species. Darwin's insight was that, even though zombie's don't reproduce sexually, random mutations in hereditary material can be passed along after a zombie bite. Each "daughter zombie" then inherits the traits of their parent and pass those traits along to their victim in turn.
It is now known that, after an attack that punctures the skin, prions transferred through zombie saliva initiate a physiological process that attacks the central nervous system of their victim. At the same time, an associated virus infects the new hosts' DNA and generates novel protein production that can alter a new zombie's phenotype (some researchers speculate that the virus and prion are actually the same, but this remains controversial). What is known is that mutant variants in this hereditary material can result in new zombie species. Those variants that are unsuccessful in feasting on human flesh won't leave as many "offspring" as those with beneficial mutations.
We are now quite familiar with how powerful an idea this is and have seen its effects in our own lives. In 1968 the common North American zombie (Z. romero) had few competitors in the niche they'd carved out for themselves (eating the brains of small town residents), but a veritable explosion of zombie diversity has occurred in the last thirty years demonstrating the power of Darwin's ideas. Below are just a few of the species that have emerged in North America alone:
Zumbi romero was originally indigenous to rural Pennsylvania but has since expanded nationwide and is the most recognizable species after six popular documentaries.
Zumbi jacksoni (here photographed with their discoverer in 1983) exhibit increased calcification of cranial soft tissue and syncopated locomotion. The unique behavior of this species to engage in choreographed movements (seen in this short film presented before the National Academy of Sciences) brought the field of zombology from the academic fringes into the mainstream.
Zumbi nemesi is characterized by an enlarged cranium and the expansion of sternocleidomastoid, semispinalis, and capitis musculature that can detach to form tentacles (species description here).
Zumbi crimsoni are known for their extraordinary speed and flexibility. Scientists consider that the unusual characteristics of Z. crimsoni and Z. nemesi are examples of artificial selection and there is speculation that an outbreak of unstable T-virus could be responsible.
Of course, Darwin's insight into the origin of zombie species is of more than mere academic interest. As these creatures wreak havoc in our world today we can utilize our modern understanding of evolution to wage battle, not with shotguns and automatic weapons (though keep those handy), but with the power of science.
I will emphasize some of the key strategies that Darwin's insights can give us to help in the zombie apocalypse in my following post. Stay close to your monitors and, for God's sake, don't go outside alone.
Update: MY DEFENSES ARE BEING BREACHED!!!! Here is my final advice to the living to defend against this threat!
Very thorough. I think we need to have greater research into the choreographed movement of Z. jacksoni. Is it a dominance competition or a method of communicating the location of potential victims much like honeybee dances.
There are SOME SERIOUS research about the zombies. You forgot about the Yeti Zombie and the Gargantuar Zombie documented in Plants vs Zombies.
Great job, Eric. This is nicely written for laymen not familiar with some of the technical terms regarding reproduction such as chromosomes and gametes. I like the progression display, but how did you get my picture for the Homo Sapien step in the progression?
BTW - I like your article on surviving the apocalypse - I have a zombie apocalypse prediction date on my blog wezombie.com, which is based on data analytics updated daily. We currently have some time to prepare as the date is now in May of 2027.
@Adam: I think you're on to something. If we could radio collar specimens of Z. jacksoni and track them following their display perhaps we could decipher whether or not communication is taking place.
@J: Technically the Yeti is an abominable snowman, totally different genus. However, I agree that the work with Z. gargantuari is impressive (particularly the research that shows their susceptibility to jalapeÃ±os).
@Bill: Thanks for the link! You've got quite an impressive compendium of research yourself. Good hunting.
Your taxonomy has a big problem, since when does an organism become an entirely different species just by being parasitised? Of course the parasite has its own name, but this is not the same as renaming the host when it becomes parasitised. While the host may be "dead" for ethical purposes (which is why it's OK to decapitate your friend if she or he becomes infected), it is clear that the bulk of the host tissue is still intact and living, including major organ functions.
Also, viruses don't have Latin binomial names like organisms. Please see the ICTV's explanation here. "Nomenclature of viruses and sub-viral agents is independent of other biological nomenclature. Virus and virus taxon nomenclature are recognised to have the status of exceptions in the proposed International Code of Bionomenclature (BioCode)." http://www.ictvonline.org/codeOfVirusClassification_2002.asp
I understand you're doing this research in a very small niche but please follow international standards otherwise this could lead to a lot of confusion and problems when you publish.