Cat populations seem to have grown in two waves, the authors found. Middle Eastern wild cats with a particular mitochondrial lineage expanded with early farming communities to the eastern Mediterranean. Geigl suggests that grain stockpiles associated with these early farming communities attracted rodents, which in turn drew wild cats. After seeing the benefit of having cats around, humans might have begun to tame these cats.

Thousands of years later, cats descended from those in Egypt spread rapidly around Eurasia and Africa. A mitochondrial lineage common in Egyptian cat mummies from the end of the fourth century B.C. to the fourth century A.D. was also carried by cats in Bulgaria, Turkey and sub-Saharan Africa from around the same time. Sea-faring people probably kept cats to keep rodents in check, says Geigl, whose team also found cat remains with this maternal DNA lineage at a Viking site dating to between the eighth and eleventh century A.D. in northern Germany.