The golden retriever is a descendant of a canine that lived two million years ago (Getty)
The retriever is one of the most striking dog breeds thanks to its luxurious coat of golden fur.
Scientists have been trying to understand where the colouring came from and believe it originated in an extinct canid that split from the common grey wolf millions of years ago.
This goes against the theory that golden retrievers emerged through years of selective breeding at the hands of humans.
The colour and pattern of a dog’s coat comes from genetic mutations that change over the generations.
Professor Danika Bannasch, a co-author on the study resulting from the research, said: ‘While we think about all this variation in coat colour among dogs, some of it happened long before ‘dogs’ were dogs.’
‘The genetics turn out to be a lot more interesting because they tell us something about canid evolution.’
Dogs have two different types of colour pigment that affect what colour their coats become (Getty)
Wolves and dogs can have two different types of colour pigment, a black one called eumelanin and a yellow, pheomelanin.
The yellow pigment is produced by what’s called an agouti signalling protein, or ASIP for short.
Regulating the production of these two pigments at exactly the right place and time on the body is what gives rise to different colour patterns.
Researchers from the University of California, Davis examined five different dog coat patterns, which were renamed dominant yellow, shaded yellow, agouti, black saddle and black back.
No single genetic mutation could account for all five of these variations, the researchers found.
Rather dogs needed mutations in two areas of the ASIP gene to get different yellow coat patterns.
This gene is shared with arctic white wolves and are much older than anticipated.
It originated in an extinct canine species which diverged from a common ancestor of both dogs and wolves around two million years ago, the researchers found.
Dogs only became domesticated around 30,000 years ago (Getty)
Professor Bannasch, who has a passion for raising and training dogs, said: ‘It didn’t come from modern wolves. It had been around for much longer.’
The genetics of ancient wolves and dogs were tested to confirm the dominant yellow colour had been around for two million years, long before dogs first became domesticated some 30,000 years ago.
The black back pattern was found in a dog sample dating back 9,500 years, which suggests rich variations already existed in canine companions.
Lighter coat patterns were likely to have been advantageous for canines who lived during glaciation periods 1.5 to 2 million years ago, the researchers say.
Natural selection would have then made sure the pattern persisted among the population which eventually gave rise to dogs and wolves.
Lighter coats would have helped dogs living during glaciation periods millions of years ago (Getty)
Co-author Dr Chris Kaelin at the Institute for Biotechnology in Huntsville, Alabama said: ‘We were initially surprised to discover that white wolves and yellow dogs have an almost identical ASIP DNA configuration.
‘But we were even more surprised when it turned out that a specific DNA configuration is more than two million years old, prior to the emergence of modern wolves as a species.’
The findings were published in the journal Nature Evolution and Ecology.