How Many Rats Are There in the World?
WouterThere are various estimates as to how many rats live in the world. In the 1950s, there were estimates that there were 2,000 rats per square kilometer in sewers. That translates to about 1.6 million rats in urban areas. The same estimate was applied to rural areas, such as in farms and agricultural buildings.
If rats were not controlled by humans, they would be much more common. Some people eat them, but other people consider them a nuisance and a carrier of disease. The famous Italian island Montecristo was infamous for being infested with black rats in the late 2000s. The Italian government has attempted to eradicate the rat population there through aerial poisoning tactics.
Rats are nocturnal animals, leaving their nests at dusk. They breed rapidly and can produce litters of up to 12 young rats a year. Their population can reach half a billion rats within three years. However, these animals are also economically important, as they provide food and fur for humans.
Scientists use laboratory rats to study many different aspects of human health and disease. These rodents are used in neuroscience research, cancer research, and toxicology studies. It is estimated that dozens of millions of animals are used in scientific experiments every year. More than half of them are rats and mice. Other animals are used in smaller amounts.
