Australia is home to an estimated 20 million feral cats, which prey on more than 100 of the country’s native species and have helped drive at least 27 species to extinction. Government officials recently sparked an international outcry after announcing plans to cull at least two million of the cats. But where did they come from in the first place? One theory held that the cats arrived with European explorers in the late 18th century, while another suggested that the cats came much earlier, around 1650, with Malaysian fishermen. According to a study in the journal BMC Evolutionary Biology, genetic testing of the cats indicates that they are probably descended from those brought by European settlers in the 19th century.