Cultural history: The rat: from plague carrier to laboratory animal

After the heavy rain of the past few weeks, drowned rats can be seen again in Berlin and other major cities, which were washed to the surface when the sewers were overloaded. As animals that follow human settlements, they can show that important living conditions change with the climate.

In Europe there were repeated phases in which rats spread, for example when Roman legionnaires moved north, then during trade relations in the Middle Ages, but also in the last century when rats in rural areas through structural changes to barns, attics and a Changes in storage in silos made access to grain and food more difficult. Here the animals followed the people into the city.

They are considered intermediate hosts for plague bacteria and were, for example, infested with fleas, which transmit the plague pathogen – although recent research shows that body lice probably also transmitted the plague from person to person. The most repulsive are sewer rats, which do little other than many rodents related to them. The original brown rat, Rattus norvegicus, is an omnivore, feeding on plants, insects and meat. She cannot cover her need for B vitamins such as vitamin B12 and high-quality proteins with plant-based food alone.

Diet filled with disgust

Therefore, rats as well as rabbits, guinea pigs and chinchillas are among the animal species that eat excrement (not always just their own). In this way, they can get a better supply of certain vitamins and proteins that are produced by bacteria in the appendix. It is normal for brown rats that around 30 percent of their diet consists of their own appendix feces, which they swallow without chewing. In this way, the animals also ensure their supply of vitamin K.

Basically, coprophagia, as the technical term goes, is a brilliant idea that even malnourished dogs, but humans very rarely come up with, and then only under duress or in a psychotic state. Generally, people look down on this behavior of animals with disgust and contempt.

This is probably why millions of animals were abused as laboratory rats. Their rapid reproduction within a few months and their short lifespan of two to three years compared to humans make rats the ideal laboratory animals for research.

Rats certainly have a physiological similarity to primates and humans. Rat-like animals that lived in the age of dinosaurs are considered the common ancestors of mammals. Werner Rothmaler and Ilselotte Groth already pointed out the five-rayed hand and foot of our rat-like, very early ancestors in a chapter of “Space, Earth, Man”. Today’s rats can also grab and hold things with their front paws. They are intelligent, social, helpful, considerate and sensitive towards their (weaker, younger) peers.

Animal testing can be replaced

However, animal experiments are not sufficient to test drugs that are effective for humans. Clinical studies with volunteer patients are always necessary here, criticize Ingrid E. Newkirk and Gene Stone, the authors of the book “Animals. Who they are and what they mean for our coexistence.”

After all, since January 2019, the test for abnormal toxicity in drug development, which was previously required in Europe, has been abolished. In this case, it was observed whether test animals developed certain malformations after administration of the substances. An even larger number of animal experiments is superfluous and unnecessary in the 21st century, explains animal rights activist Ingrid E. Newkirk. Various in vitro technologies using cultured human cells or mini versions of human organs can also be used to test the safety of drugs and chemicals.

Rats as pets

Perhaps the trend of keeping a brown and white colored rat as a pet can bring about a rethink and a change of perspective on these clever animals. These so-called pet rats often come from laboratory rats. They are capable of close friendship with humans.