A genetic discovery could help save the Scottish wildcat from extinction, scientists have suggested.
The wildcat is one of Scotland's most endangered species
A genetic study found 26% of European wildcats shared DNA characteristics with domestic and Near Eastern cats.
Cross-breeding with feral domestic cats has threatened the future of Britain's most endangered carnivore.
Conservation experts will use DNA in their work with Scottish Natural Heritage as they try to establish the number of wildcats in Scotland.
Comparison of genetic sequences enabled an international group of researchers to determine the relationships between different cat lineages.
In the course of the study, reported in the journal Science, scientists found that 28 out of 108 European wildcats carried DNA characteristic of domestic cats and their Near Eastern relatives.
The only way this could have happened was by cross-breeding between domestic cats and European wildcats.
This genetic mixing now threatens the existence of modern wildcats.
An extremely rare Scottish wildcat kitten was born in captivity in Kent
Prof David MacDonald, director of the Wildlife Conservation Research Unit (WildCRU) at Oxford University, has devoted more than 10 years to the conservation of the Scottish wildcat.
He said: "The most exciting thing about these genetic insights from the past is that they offer hope for the wildcat's future.
"In Scotland we've been striving to find a genetic marker to identify Scottish wildcats, and now we have one."
Prof MacDonald added: "Whatever the future holds, the domestication of the cat to complement human civilisation stands out as one of the most successful 'biological experiments' ever undertaken by humans."
The wildcat, once found throughout Britain, is now thought to exist only in northern Scotland.
The Scottish wildcat is said to be Britain's rarest mammal.
There are only about 400 of the cats left in the world and scientists warn they could become extinct in our lifetime.