Norway rats (Rattus norvegicus) are also referred to as “brown rats”, “sewer rats”, and “wharf rats”. They are moderately large, robust, brownish or grayish rodents that can grow up to 40 centimetres long (their tails measuring about 21 centimetres) and weigh up to 500 grams. These rats can burrow 12 to 18 inches underground to make a nest and enter your house in search of food and water.
Norway rat ancestors are known to originate in Asia. The first recorded fossil can be traced back about 54 million years ago, at the end of the Paleocene and earliest Eocene in Asia and North America. They are believed to be have descended from rodent-like ancestors known as anagalids, which have given rise to Lagomorpha, or rabbit group.
Present-day Norway rats originated from Murids, which first appeared in the in the late Eocene era, about 34 million years ago.
The genus Rattus (a native to the Mediterranean countries, Middle East, India, Japan, China, and Southeast Asia) evolved within the Murid family dating back 3.5 to 5 or 6 million years ago. After its evolution, there was an intense speciation that occurred in the Rattus genus, the earliest about 2.7 million years ago and the other one about 1.2 million years ago and is still ongoing.
The ancestors of the Rattus norvegicus (Norway rats) and R. rattus (black rats) began to split about two million years ago.
- Asian History of the Norway Rats
While they are called Norway rats, they do not originate from Norway. According to the Washington Department of Fish and Wildlife, they are a native of Asia, specifically China, Japan, India, and other Indo-Malayan countries.
- Commensalism with Humans
Commensalism or the association between human and rats was believed to have started thousands of years ago. Both rat species began to take shelter in human homes, buildings, and ships.
- Arrival in Europe
Although Norway rats are native of Asia, they arrived in Europe via Norwegian ships. However, it was believed that black rats came to Europe before Norway rats, and the latter have arrived several centuries after.
- Spread beyond Europe
Norway rats were reported to reach North America in 1755 through the ships of the new settlers, while the black rats reached the New World in the 16th century. Today, Norway rats are more common than black rats in both North America and Europe.
- Earliest Captive Rats
During the famine that occurred in the eighteenth and nineteenth century, Norway rats were captured and used as food in Europe. Rat-catchers were also hired to eliminate rats. Captured live rats were also used for rat fights, rat pits, and rat coursing. Wild rats were captured and caged, as well.
- First Lab Rats
In 1828, rats, particularly the Albino ones, were brought to science laboratories for physiological studies. The first breeding experiments were conducted in the 1870s and 1880s. European-origin white rats were brought to America and became the foundation stock of the American laboratories.
With the increasing population of Norway rats, they have invaded our homes and posed serious health problems to the household members. To prevent potential infestation, hire a professional who offers services in rat removal in East York to check your house, seal possible rat entry points, and eliminate them permanently.