Genetic analysis of camel bones from Al Sufouh and other sites in the UAE forms a major part of a new study, which suggests that south-east Arabia, now known as the UAE and Oman, was probably where the dromedary was domesticated.
With its free zones, luxury hotels and villas, Al Sufouh in Dubai seems to encapsulate perfectly the city’s rapid development and limitless ambition.
But turn the clock back about 4 millennia and this area, now home to Dubai Media City, Dubai Knowledge Village and much more, was a very different place.
Nearby there was a tidal creek system with broad mudflats containing what scientists have called “islands” packed with salt-rich plants or halophytes. These salty plants were, along with dry grass, just what wild camels liked to eat.
In the early 2000s, excavations in Al Sufouh revealed an incredible bounty: the remains of nearly 18,000 camel bones, including a complete skull. It was something quite out of the ordinary and the work of more than just nature.
“Normally you find a bone here or there,” says Prof Joris Peters, a palaeo anatomist at Ludwig Maximilian University of Munich who has worked on identifying and analysing the bones.
“This was one of the slaughtering places. They just butchered it on the spot and carried away the pieces.
“We found spots where people were probably returning for decades because they knew the animals were coming. It’s predictable if you’re in need of halophytes. The animals come back.”
It is eight years since researchers published a paper describing the bones from Al Sufouh. They concluded that the area was a key place for hunting and butchering wild dromedaries.
Genetic analysis of bones from Al Sufouh and other sites in the UAE forms a major part of a ground-breaking new study, shedding light on how the creatures were domesticated.
Published in the journal Proceedings of the National Academy of Sciences, the work suggests that south-eastern Arabia, now the UAE and Oman, was probably where the dromedary was domesticated.
Prof Peters and the other 23 researchers who wrote the paper – “Ancient and modern DNA reveals dynamics of domestication and cross-continental dispersal of the dromedary” – have also found that modern, one-hump camels in different parts of the world share much in common genetically.
Rather than forming distinct populations, they have exchanged genetic material with one another during history, a consequence of being led along trade routes.
A major reason scientists have been able to draw these conclusions is that genetic analysis has moved in leaps and bounds in the past decade.
“Whatever understanding people had in the past about how domestication happened has changed a lot since we’ve managed to obtain genomics,” says Dr Pablo Orozco-terWengel, a lecturer at Cardiff University in the UK.
“We have more data to support and test different hypotheses.”
Dr Orozco-terWengel is co-author of the new study and worked on the various theoretical models of how domestication took place.
The scientists carried out genetic analysis on 1,083 camels from today, and on early domesticated camels − between 2,500 and 300 years ago − from Syria, Turkey, Jordan and Austria.
Oldest were the camel remains found at four sites in the UAE: from 1,260 to 500BC in Tell Abraq in Sharjah; 2,400 to 1,400BC at Al Sufouh; 3000 to 2000BC in the Umm An Nar island in Abu Dhabi; and 5,000 to 4,000BC in Al Buhais inland in Sharjah.
The scientists were able to analyse DNA from the mitochondria, which are energy-generating organelles that have their own genetic material, separate from that found in the nuclei of cells.
Prof Michael Hofreiter, a researcher at the University of Potsdam and another co-author of the paper, said the ancient DNA samples from the UAE represented only a “small data set”, but one that was “reasonably informative”.
The samples contained some haplotypes, or sets of genes inherited from a single parent, also found in modern camels.
This is important because it suggests that modern camels can largely be traced back to an ancestral wild population in south-east Arabia, so the UAE and parts of Oman could well be where camels were domesticated.
If these genetic similarities had not been found, the conclusion would have been very different.
“We would’ve said we’ve looked at the wrong ancient population,” said Prof Hofreiter.
So the genetic evidence appears to confirm what had seemed to be the case from archaeological studies: that camel remains from the UAE are probably the founder populations of, or closely related to, the domesticated dromedary.
It is an outcome that has thrilled another of the authors, Peter Magee, a professor of classical and near-eastern archaeology at Bryn Mawr College in Pennsylvania, who has been coming to the UAE sites since 1993.
“The archaeological research pointed to the region as a potential source of domestication. The genetic work, from a completely different angle, is pointing in the same direction,” said Prof Magee.
“It doesn’t mean we held the camel that was first domesticated but it seems to be that was the population that then became domesticated.”
With the help of the Sharjah Directorate of Archaeology under Dr Sabah Jasim, Prof Magee and others have made incredible discoveries at Tell Abraq and Muweilah in Sharjah.
One find at Muweilah was a beautiful 900BC camel figurine, something that indicates a close bond between people and camels.
If domestication did take place in this part of the world, it poses the question: why here?
One factor, says Prof Magee, is the long history of human settlement. This, coupled with the interaction of these people with the creatures around them, provided the ingredients for domestication.
“We know from these and other sites that people were hunting camels for thousands of years,” he said. “Hunting as a precursor to domestication seems to make sense.”
As the paper points out, it seems possible that when domestication took place, the wild ancestors had a relatively limited geographical distribution, being restricted to the Arabian south-east coast.
The research has highlighted the way in which today’s camel populations in different parts of the world tend not to be very distinct from one another genetically, a legacy of their long travels with people.
“From Central Asia, people moved them over Samarkand to the Middle East. They would leave the animals there and pick new animals. The animals were left for resting probably,” says Dr Orozco-terWengel.
Another notable finding is that camels show an unusually large amount of genetic diversity for a domesticated animal.
A complex statistical analysis of the genetic evidence suggests that, after domestication – at the end of the second millennium or the start of the first millennium BC – there was interbreeding between wild and tamed camels.
This transferred genetic diversity into the domesticated camel before the wild animals died out.
It represents what Dr Orozco-terWengel describes as a domestication history that is “slightly different from the traditional”.
This legacy of genetic diversity could be of interest beyond science. It means the creatures should be able to adapt to the new conditions from climate change.
“The more genetic variation, the better you’re able to cope with what the environment throws at you, like disease or climate change,” Dr Orozco-terWengel says.
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