drferox:

Okay folks, listen up for this very important lesson: Bananas are not special.

If we have to worry about bananas in a zombie apocalypse scenario we are in much bigger trouble than anyone anticipated.

There’s a huge amount of confusion in how DNA sequences are compared between people or species, and that makes taking quotes and figures out of context extremely messy.

By and large most living things on the planet will share about half their DNA with any other living thing on the planet. A lot of the intracellular machinery is the same, there’s only so many ways you can build mitochondria!

Any given human is about 99.5% the same as any other given human, so when we talk about having half of your mother’s genes, really you have 99.75% of your mother’s genes and 99.75% of your father’s, it’s just that lots of them happen to be the same.

If you’re using genetic similarity to determine whether a species can also be infected by a zombie pathogen, and you’re using 60% similarity to humans as your cut off point, then we also have to worry about:

• Cats at 90%
• Dogs at 82%
• Cattle at 80%
• Rats and mice at 69% and 67%
• Chickens at 60%
• Fruit fly at 60%

In short, if bananas are also affected by a Zombie Pathogen, so is every other living thing on the planet except perhaps something lurking down at the bottom of the ocean on a volcanic vent that hasn’t even seen a molecule of oxygen in the millennia it’s existed.

Basically, all that 60% figure means is that humans and bananas are largely made up of the same materials. Since humans can eat bananas and turn the banana into energy and human flesh, this isn’t surprising. 

Also, a pathogen that infects humans is a pathogen that infects mammals. It’s rare for a pathogen to jump between species, even rarer for it to jump between groups (ex. mammals and birds), and pretty much unheard of for a pathogen to jump between endothermic and ectothermic animals. There are 3 pathogens that are known to infect both humans and plants, and the symptoms they cause are relatively mild and mostly immune-related. 

That said, if we’re dealing with all-out worst-case-scenario supervirus that can infect anything at least 60% related to humans (which wouldn’t make much sense, since the differences are all in major things like body chemistry, metabolism, and, y’know, whether it’s a mammal or an insect or a plant), the world would be doomed. The only survivors would be things deep enough in the ocean to avoid the disease, maybe things in the ocean in general if the virus can’t survive saltwater. Which, if it can infect that many things, it probably can. 

To answer the above question, it wouldn’t make any sense for a disease to cause fruit to rot faster, as that would make it inedible. If a virus that primarily infects mammals can also infect plants, it’s probably using them to spread. If anything, it probably contains anti-rot compounds, which would also make sense to preserve the zombies. And, yes, exposure to a zombie corpse or zombie blood would probably be how that disease would be transmitted. And, yes, if a zombie virus somehow modifies itself to infect fruit trees in order to infect more humans, eating a zombie virus banana would make you sick. It wouldn’t be a rotting banana, though, it would probably be the best banana ever up until you got sick. 

Now, a zombie virus that infects mammals in general and can also infect plants specifically to spread to other animals? That’s a bit more likely than “can infect anything that’s at least 60% related to its host”. 

(and rotting in “the normal way” is rotting through decay. Consumption by various bacteria and gradual breaking down of various compounds. Decay and rot are synonyms.)