Trending Science: Camel genetics shaped by ancient human trading routes

A team of scientists have discovered that the genetic diversity of one of the world’s most domesticated animals – the dromedary (one-humped) camel – has been shaped by ancient trade routes.

For thousands of years people have used the dromedary camel as a means of transportation for both humans and goods. Well into the twentieth century, trade caravans consisting of up to thousands of animals would crisscross the deserts of North Africa and the Middle East. The dromedary is the largest domesticated livestock species and its domestication was fundamental to the development of human society in harsh, inhospitable desert environments. However, many open questions have remained regarding the dromedary’s domestication and evolutionary history.

During the domestication process, humans usually breed the animals by selecting those parts of the genotype that bring the most benefit. The research team, coordinated from the University of Veterinary Medicine, Vienna, has shown for the first time that this was not the case with the dromedary. Unlike other examples of domestication, where a low genetic diversity is the norm, the dromedary camel exhibits enormous genetic diversity.

The research team, coordinated from the University of Veterinary Medicine, Vienna, collected samples from nearly 1 100 extant dromedaries and compared these with archaeological samples from wild and early-domesticated animals. Using DNA analysis, they determined that the dromedary’s genetic diversity is directly related to its use as a transport animal on ancient trading routes across the Middle East and North Africa. This allowed for different dromedary populations to have contact with each other, resulting in a more regular gene flow and the maintenance of genetic diversity within the species. Only one dromedary population deviated from the genetic diversity of the rest of the species, due to being isolated for some time as a result of geographic and cultural barriers.

As a consequence of the dromedary’s regular gene flow, which is usually only found in wild animals, it has been difficult to determine the wild form from which today’s domesticated dromedary camel is descended from and, therefore, when it was first domesticated. The research team was able to successfully answer this question.

They did this by analysing DNA of up to 7 000 years old from the bones of wild and early-domesticated dromedaries and compared the samples with the genetic profiles of modern dromedary populations from across the world. For the first time, it was possible to identify the coastal Southeast Arabian Peninsula (modern day Oman and the United Arab Emirates) as the region of first domestication.

‘Our results appear to confirm that the first domestication of wild dromedaries occurred on the southeast coast,’ commented Pamela Burger, a member of the project team based in Vienna. ‘This was followed afterwards by repeated breeding of wild dromedaries with the early-domesticated populations. The wild ancestor of today’s dromedary had a geographically limited range and went extinct around 2 000 years ago.’

The genetic diversity of the dromedary camel is likely be much more adaptable in the face of a changing environment compared to other domesticated and livestock animals. It has even been speculated that due to warming temperatures, more extreme weather patterns, and consequently more areas becoming unsuitable for livestock production, that the camel could eventually replace cattle, and even sheep, as the primary source of milk and meat for humans.

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