In the near-future, a hitherto-undiscovered island becomes a training and research facility for an unnamed nation’s military. One field of research taking place on this island is in the development of genetically-engineered bioweapons.

One of these experimental “weapons” is rattus norvegicus cognitus; a subspecies of the brown rat or Norway rat whose intelligence and lifespan is greatly increased. These rats, (who have an IQ of about 100 and an average lifespan of 30 years) are intended for use as spies and foot soldiers that can sneak into enemy camps without ever being discovered, and gather information without conspicuous wearable cameras/microphones.

However, a war breaks out, and the unnamed enemy discovers this island. The base where the rats were developed is destroyed, but some of the rats escape and begin breeding in the island’s lush forests and wildernesses. Over time, these intelligent rodents develop a civilisation.

I intend for these rats to begin to farm crops on the alpine slopes of this island. However, I am not sure what the best food crops would be, hence my query.

Here are a few specifications:

  • the crops are being cultivated on the grassy slopes of the now-extinct volcano which lies at the centre of this small island.

  • these slopes are at an elevation of less that one kilometre.

  • the island has a dry-summer climate, similar to that of the Mediterranean.

  • the crops have to be able to be harvested easily by rats, and so should ideally be no more than a foot tall when fully grown. For this reason I am avoiding cereal crops such as wheat.

  • the rats have access to protein from fishing along the coast, so the main nutrients these crops have to provide are vitamins and fibre.

  • as rats do not typically hibernate, these crops should either grow throughout the year or produce a food source that can be stored over winter.

  • $\begingroup$ Is the height restriction really an issue given rats' prodigious abilities to chew through virtually everything, including wheat stems? I think it'd be more of a matter of what they can lay their paws on, given that most of our staple crops have been bred for thousands of years, so without access to seeds they can sow they're left with whatever wild species they can cultivate. On the plus side though, once they harvest the crop, it can be stored for a long time as they don't have to worry about the main pest of granaries: rats. $\endgroup$
    – biziclop
    Commented Mar 20, 2023 at 14:59
  • $\begingroup$ Rats and humans have co-existed so long that we and they eat pretty much the same thing. If the rats that exist now evolved to sentience, they would probably eat what we eat. $\endgroup$
    – Boba Fit
    Commented Mar 21, 2023 at 14:01

3 Answers 3



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The good news is you do not need to harvest the yummy part from high above the ground. The yummy part is underground instead. The bad news is you have to go underground to get the potatoes. You have two options.

Low Tech Option.

Dig a tunnel under the plant and get the potatoes directly. Choose a cultivar with many small potatoes instead of fewer big potatoes. Rats are good tunnel diggers:

enter image description here

High Tech Option

Your rat people have the technology to build a fishing boat, and pull fish aboard. Presumably they can also coordinate enough to make a big hole in the ground and pull potatoes out.


They wouldn't limit themselves to a single crop

With an IQ similar to that of humans, it is unlikely that the rats would rely on a single crop. Humans don't just concentrate on what the "best" crop is for us, they plant all sorts of things to have a varied and balanced diet.

A realistic list of good "Rat Crops" are as follows:

  1. Grapes typically thrive in a Mediterranean climate, and why wouldn't the rats want wine? (any other naturally occurring berry bush will also be a hit)
  2. Olives. While an olive tree does technically violate the one foot high rule, the rats could certainly climb trees, or just wait for the fruit to fall.
  3. Any naturally occurring fruit tree. Orchards would be a great crop for rats, even if they can't climb, the fruit will drop eventually.

Also it seems silly that an intelligent rat be dissuaded by something as trivial as the food being too high up. There should be no reason why wheat, barley, or rice should be eliminated on that account as the rats could easily just cut the stalks down.

I believe their main problem will be seed acquisition. They will be limited by what is already growing in their habitat, and perhaps some additional seeds salvaged from the ruin of the research center.

  • 1
    $\begingroup$ To be fair, while the rats may be smart enough to chew through crop stalks and such, they are still less than 30 cm long and 0.5 kg in weight. I don't think they have the strength for large-scale engineering. So RIP rice, wheat, and stuffs on account of not having big enough plows $\endgroup$ Commented Mar 21, 2023 at 10:49

They are on a small island. I doubt they would have a lot of choice.

Their agricultural crops would be limited to whatever the bioweapon laboratory had on hands and local fauna. Wheat - extremely unlikely. Rice, potatoes, carrots - maybe. If rats managed to preserve them after laboratory destruction.

Local flora unlikely to offer many options known to us, but rats are omnivores, they would find something to eat in "lush forests and wildernesses". According to wikipedia "millets are indigenous to many parts of the world". I would say, that's their best bet. Rats like grain.

Generally speaking they would be crazy to start farming. That's like a giant sign "here we are, come and get us".

Weight of Rattus norvegicus (brown rat) is 140 to 500 grams. Weight of human brain is 1.2-1.4 kg. With the same level of intelligence and lower food requirements these rats are clearly superior beings to humans. Military scientists who made them were absolute geniuses.

The population of brown rat can grow from 2 to 15,000 in a year. The only reason we are not up to our necks in rats is estimated life span of 3 years and yearly mortality rate of 95%. Sentient rats live 30 years and don't die all that much.

Agriculture can't sustain this reproduction rate. Rats would have to control their population. With controlled population they can live very comfortably in "lush forests and wildernesses" without agriculture. Exterminate all predators that can harm a rat on the island. It would make it ideal for small animals. Hunt them for meat, gather everything else. Forget fishing.

Sitting on the island and waiting for people to return would be a suicide. Send expeditions outside. Hide among normal rats, take from humans everything necessary. Learn and build up technology. When ready build up numbers and take over the world. A matter of few decades.

  • $\begingroup$ 1+ upvote for suggestions on possible crops and the comment on population growth; rats will clearly need some method of controlling this. Perhaps a culture that frowns on polygamy. $\endgroup$
    – user98816
    Commented Mar 21, 2023 at 16:51

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