How Did Rats Get to America?

Rats are not native to the Americas, but they have been invasive ever since Europeans started to colonize the continent in the 18th century. They were likely introduced from Asia and Europe via shipping and stowing away in ships. By the 18th century, Norway rats had colonized most of Europe and were brought to America by ships. Once there, they quickly displaced other species of rats from cities in the Americas. Today, Norway rats co-exist with Black rats in some parts of the country and nest in palm trees in California.

Ancient DNA analysis of rats’ genomes has shed light on how this pest spread across Europe, where it is blamed for spreading the Black Death. Researchers at the University of York, University of Oxford, and the Max Planck Institutes for the Science of Human History and Evolutionary Anthropology conducted the analysis. The study is the first of its kind to use ancient genetics to study the black rat.

The domestication of brown rats is complex and may have occurred in several stages. The first domestication event occurred in Japan in the 1600s, followed by one in Europe in the early 1800s, and finally in North America in the mid-1800s. During this period, the rat went through a series of events, including selective breeding. Afterwards, these rats were used for different purposes.