Domestic dogs started developing into different sizes and shapes thousands of years ago rather than hundreds, a new study claims.

Scientists at the University of Exeter have analysed hundreds of archaeological canine specimens spanning the last 50,000 years. 

They've managed to pinpoint the surprisingly early time dogs began to physically diversify – around 11,000 years ago. 

The findings challenge 'long-standing assumptions' that dogs look different only because of selective breeding since the Victorian era. 

The researchers don't deny that the Victorians were largely responsible for what we now know as breeds. 

But their study shows that an array of physical diversity in dogs dates back much longer ago than commonly thought.

'These results highlight the deep history of our relationship with dogs,' said study author Dr Carly Ameen of Exeter's department of archaeology and history. 

'Diversity among dogs isn't just a product of Victorian breeders, but instead a legacy of thousands of years of coevolution with human societies.' 

Working with colleagues in France, the scientists analysed 643 modern and archaeological skulls belonging to the dog family (canid).

The sample, dating back 50,000 years, included recognised breeds, street dogs and wolves. 

The researchers also created 3D models of the skulls to better study their size and shape.

Results showed a wide range of skull shapes and sizes among domestic dogs 11,000 years ago, not too long after their divergence from wolves. 

At the time, there was not the extreme skull shapes of modern breeds such as pugs or bull terriers, according to study author Dr Allowen Evin at CNRS in France. 

'But Mesolithic and Neolithic dogs already displayed about half of the total cranial variation observed in modern dogs,' she told the Daily Mail. 

'This means that early dogs varied considerably in skull size and proportions.' 

The earliest specimen identified as a domestic dog came from the Russian Mesolithic site of Veretye dating to about 11,000 years ago. 

The team also identified early dogs from America about 8,500 years ago and Asia (7,500 years ago) with 'domestic skull shapes' – proportionally shorter and wider compared with those of wolves.

After that, even more variation emerged relatively quickly, which likely reflected dog's diverse roles in early human societies, from hunting and herding to companionship. 

Overall, dogs have 'undergone extraordinary physical diversification' over the past 11,000 years, Dr Evin said.

'Modern breeds now range from chihuahuas to mastiffs and from flat-faced pugs to long-snouted greyhounds – forms far more extreme than anything found in the archaeological record,' she told the Daily Mail. 

Dr Dan O'Neill, professor of animal epidemiology at Royal Veterinary College who was not involved with the study, agreed that diversity of the canine body as an overall concept has been around for thousands of years.

However, he stressed the selective breeding of extreme and unhealthy body shapes is a much more recent phenomenon, dating back to about the late 1800s. 

Ever since the Victorian era, dogs have been selectively bred to accentuate harmful features to create these so-called breeds to distinguish them from each other and fuel a dog-buying industry. 

And since then, these traits – such as elongated bodies on dachshunds and flat faces on pugs – continue to get more extreme. 

Flat faces and abnormally narrowed nostrils restrict airflow, making it difficult to breathe, especially when going for a walk or trying to chase a ball. 

Meanwhile, dogs sausage-shaped bodies suffer severe back problems due to their long spine and bowed, stubby legs, potentially leaving them unable to walk. 

'What did happen in Victorian England was the invention of breed as a concept in dogs and the formal written descriptions of what a breed should look like,' Dr O'Neill told the Daily Mail. 

'This was for the purposes of having a standard to compare between dogs in a show ring. 

'This is the recent phenomenon, and this built on the thousands of years of physical diversity to create all these new breeds that emerged around then in the late 1800s.' 

Dr Evin stressed that the study focused exclusively on skull morphology, not things like coat colour, body size or other physical traits. 

'But we can confidently identify when cranial features diverge from the wolf pattern to form what we call a “domestic” shape,' she added. 

The research has been published today in the journal Science.