How long has invasive species been around for?

The term "invasive species" is relatively new, but the phenomenon of species being introduced into new environments and causing negative impacts is not. Some examples of invasive species introductions date back thousands of years, such as the introduction of rats to the Pacific Islands by Polynesian voyagers. However, the rate of species introductions and the associated negative impacts have increased dramatically in recent centuries due to factors such as increased global trade and travel, as well as human-induced environmental changes.