 Successive litters of early European long-haired cats produced more and more long-coated offspring, which were more likely to survive in the cooler European climates.By the year 1521, around the time they were first documented in Italy, the variety had become fixed after only a few generations.In the late 18th century, Peter Simon Pallas had advanced the hypothesis that the manul (also known as Pallas's cat) might be the ancestor of the long-haired domestic cat.