Why every white horse can trace its roots back to just one ancestor thousands of year

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Why every white horse can trace its roots back to just one ancestor thousands of years ago


By David Derbyshire

They have been favoured by kings and emperors, in the form of Desert Orchid they became the housewives' choice and in 'Billy' the police horse they helped clear the Wembley pitch and helped make history.

Now scientists have identified the genetic mutation that turns horses grey and then white - and and it could mean they all trace their ancestors back to just a single mare or stallion more than 2,500 years ago.

Grey horses are typically descended from Arabian ancestors, including the famous purebred Lipizzaner stallions that are trained for classical dressage, and have been selected by humans for their striking appearance.

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All white: Racing great Lester Piggott on board Desert Orchid in 1998

Born with dark hair greys gradually lose pigmentation. As their hair becomes white between six and eight years old they take on a grey appearance due to their black skin underneath.

Dr Leif Andersson and colleagues at Uppsala University, Sweden, found mutated genes in more than eight hundred grey horses from eight different breeds.

Crucially, the variants are not present in horses of other hues and through further DNA mapping the researchers the phenomenon was nailed down to the over expression of two neighbouring genes known as STX17 and NR4A3.

It is not yet known if one, or both, of the genes, is responsible for the loss of hair pigmentation, according to the study published online in Nature Genetics.

Dr Andersson's team also point out between 70 and 80 per cent of grey horses older than 15 years have melanomas, the most serious form of skin cancer that reduces their lifespan.

They believe the defective genes trigger both the disease and the loss of hair colour through reducing protective pigment containing cells in the skin and hair follicles.

Dr Andersson analysed the coat colours and skin of thoroughbreds from five national studs in Austria, Croatia, Hungary, Slovakia and Slovenia.

One of a kind: A rider performs on his Lipizzaner horse at Vienna's Spanish Riding School

He said the grey provides a notable example of how humans have cherry-picked mutations that produce attractive appearances in domestic animals.

He said: "The manifestation of this mutation as a white horse has had a strong impact on human culture and has left numerous traces in art and literature from Asia and Europe, such as Pegasus and the unicorn."

The oldest written record is by the Greek historian Herodotus, who describes the Persian emperor Xerxes who reigned from 485 to 465 BC as keeping sacred white horses.

Dr Andersson said: "The prestige of riding a white horse has thus led to selection of the grey causing mutation by humans. This mutation is by far the most common cause of white colour in horses."

He added: "Since the first description of melanomas in grey horses in 1903, researchers have questioned how a mutation causing loss of hair pigmentation can also cause melanomas. Our results suggest a possible explanation."

Lipizzan stallions are known as the "Dancing White Horses," the only horses used by the world renowned Spanish Riding School in Vienna.

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Historic moment: Billy, the white horse, helps clear the Wembley pitch during the 1923 FA cup final

Desert Orchid, affectionately known as Dessie, has been rated the fourth best National Hunt horse of all time after the gallant grey won an incredible 34 of his 70 starts between 1983 and 1991.

Nicholas Silver captured the country's hearts in 1961 when it became only the second grey to win the Grand National after The Lamb which won twice in 1868 and 1871.

But you have to go all the way back to 1946 to find the most recent of grey horses to win the Epsom Derby when Airborne was victorious.

Possibly the most famous horse in the history of the Metropolitan Police, Billy and Pc George Scorey saved King George V and the first Wembley Cup Final in 1923 when the crowd invaded the pitch.

Scorey led Billy to clear the pitch, and thereafter both were famous, their presence requested at many events.

National icon: The Saxons carved white horses into the chalk downs of southern England. This one at Uffington< oxfordshire, was carved more than 1,000 years ago

Why every white horse can trace its roots back to just one ancestor thousands of years ago | Mail Online