Animals: How donkeys changed the course of human history

“These specimens, which were genetically related to African donkeys, were larger than certain types of horses.”

Orlando led a project to sequence the DNA of donkey skeletons. It was part of a much larger study aimed at tracing the origin of donkey domestication and its subsequent spread to other parts of the world.

The research provides startling insights into the very history of our species through our relationship with these versatile animals.

According to Orlando, the donkeys raised in the Roman villa of Boinville-en-Woëvre measured 155 cm from the ground to the withers (a ridge between the shoulder blades).

The average height of today’s donkeys is 130 cm. The only modern donkey that comes close is the American mammoth donkey, also known as the mammoth donkey, a species whose males are exceptionally large and often used for breeding.

Giant donkeys like those found at Boinville-en-Woëvre may have played an important but underestimated role in the expansion of the Roman Empire and its subsequent attempts to retain this territory, Orlando claims.

“Between the second and fifth centuries, the Romans bred donkeys to produce mules, which were crossed with horses and played a key role in transporting military equipment and goods,” he explains. “Although they are in Europe, they have been mixed with donkeys from West Africa.

But the evolution of the Roman Empire probably contributed to the disappearance of this giant donkey breed.

“If you don’t have an empire thousands of miles wide, you don’t need an animal that transports goods over long distances,” says Orlando. “There was no economic incentive to continue producing mules.”

To find out how donkeys played their role throughout human history, an international team of 49 scientists from 37 laboratories sequenced the genomes of 31 ancient donkeys and 207 modern donkeys from around the world.

Using genetic modeling techniques, they were able to track changes in the donkey population over time.

They found that donkeys may have first been domesticated from feral donkeys and were likely domesticated by pastoralists around 7,000 years ago in Kenya and the Horn of Africa. , in East Africa.

Although this date is slightly earlier than originally thought, researchers have also concluded, perhaps more surprisingly, that all modern donkeys living today appear to be descended from this single event of domestication.

Despite this, previous studies suggest that there may have been other attempts to domesticate donkeys in Yemen.

Interestingly, the early domestication of donkeys in East Africa coincided with the aridity of a once green Sahara.

A sharp weakening of the monsoon around 8,200 years ago, combined with increased human activity in the form of grazing and burning, led to less rainfall and the gradual expansion of the desert and the Sahel region.

Domesticated donkeys may have played a crucial role in adapting to this increasingly harsh environment.

“We believe that due to climate change, local (human) populations have had to adapt,” says Orlando. “As for the donkeys, they may have taken advantage of their strength and this essential service of transporting large quantities of goods over long distances and through difficult landscapes.”

They also noticed that the donkey population apparently suffered a drastic decline after being domesticated, and then increased sharply again.

“This phenomenon is typical of domestication and is seen in almost all domesticated species at some point,” says Evelyn Todd, a population geneticist at the Toulouse Center for Anthropobiology and Genomics, who also took part in the study. .

This decline is the result of the selection of a specific stock of donkeys for domestication and then their voluntary breeding, which has contributed to their large increase.

These analyzes suggest that the donkeys seem to have left East Africa, were traded in northwestern Sudan and then to Egypt, where remains of donkeys have been found in archaeological sites dating back 6,500 years. .

Over the next 2,500 years, this newly domesticated species spread across Europe and Asia, developing the lineages found today.

According to archaeologist Laerke Recht, from the University of Graz, Austria, donkeys played an important role in man’s ability to transport goods over long distances over land, thanks to their endurance and their strength. ability.

“While rivers like the Euphrates and Tigris in Mesopotamia and the Nile in Egypt could be used to transport heavy and/or bulk cargo, donkeys led to a massive increase and intensification of land contact,” explains she.

According to Recht, this coincides with the increased use of bronze during the third millennium BC. “Donkeys could transport heavy copper over long distances and to regions where it was not found naturally (or only in very small quantities), notably in Mesopotamia.”

Donkeys and other equines also changed the art of warfare around the same time.

“We started seeing them in front of wheeled vehicles taking part in battles, as well as providing transport for supplies needed by an invading army,” Recht explains.

Donkeys were so prized that they even appeared in important rituals.

“In Egypt and Mesopotamia, they were considered important enough to be buried with humans. In some cases, even with kings or rulers,” Recth says. “There are also examples of donkeys that have benefited from a proper burial”

He adds that during the second millennium BC, donkeys were also sacrificed for what are known as foundation or building deposits, i.e. holes dug in specific places. in buildings or temples where ceremonial objects were placed to prevent the ruin of the site.

They were also used as part of rituals when signing treaties.

The oldest sample studied by Orlando and his colleagues consisted of three Bronze Age donkeys from Turkey.

“Radiocarbon analysis allows them to be dated to around 4,500 years old and they have a similar genetic makeup to modern Asian subpopulations,” Todd says.

This suggests that the Asian subpopulation of the domesticated donkey diverged from other lineages at this time.

Research also confirms that the donkey has been a much more constant companion to man than its equine relative, the horse.

“Modern domestic horses, which were domesticated around 4,200 years ago, have had a major impact on human history. Today, our study reveals that the impact of donkeys extends even further away,” says Orlando.

The enduring usefulness of the animal contrasts with the attention it has received over horses and dogs. While donkeys are neglected in many parts of the world today, in some places they remain as important as they have been throughout history.

“The donkey is an important animal in the daily lives of millions of people around the world,” says Todd.

“Its population increases by one percent every year. Although donkeys are not used in daily life in developed countries, in many developing communities in regions such as Africa and the Arabian Peninsula, people still rely on donkeys for transporting people and goods.”

He adds that understanding the genetic makeup of donkeys could also help improve their breeding and management in the future.

A key question that researchers hope to answer in future studies is to find a close relative of the domestic donkey in the wild.

Orlando, Todd and their colleagues were able to identify three candidates.

“We know the donkey is a descendant of the African wild ass,” Todd explains. “We know of three subspecies: one became extinct in 200 AD in Roman times, the second probably became extinct in the wild, and the third is critically endangered.”

However, further work is needed to determine if there were or are other as yet unidentified subspecies of the African wild ass, which would improve our understanding of the genetic history of the donkey and perhaps learn more about the important role it has played in our own history.