The Vikings who settled in Iceland more than 1,000 years ago appreciate their horses so much that the men are buried with their faithful horses. And the DNA analysis of these precious animals has recently proven that horses sent to the grave with their male owners were also males.

For decades, archaeologists have studied the contents of hundreds of Viking tombs in Iceland. Many of these graves also contained remains of horses that appeared to be healthy adults after their deaths.

Because horses seemed well cared for in life – before they were killed and buried – they were considered important for men whose remains were nearby. Scientists recently performed the first old DNA analysis on 19-horse bones in Viking tombs and found that almost all the animals were male, a tantalizing clue to the extinct Viking culture. [Fierce Fighters: 7 Secrets of Viking Culture]

Iceland is home to 355 known Viking tombs dating from the late 9th century to the early 11th century and its occupants are mostly middle-aged men, according to a new study. Horses are common in these graves – more than 175 horses appear in 148 graves. The majority of animals were clearly associated with human skeletons and they appeared to have been shot "specifically for burial," scientists said.

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Previous interpretation of the remains of horses from other Viking sites suggested that male horses played an important role for the Vikings. And the researchers suspected that learning the sex of Icelandic horses buried would provide valuable information on funeral rituals.

Experts can differentiate the remains of male and female horses by examining the shape of the pelvis of the animal and that of the canines, which usually appear only in men, according to the study. But this type of analysis only works if the remains are in good condition, said to Live Science, Albína Hulda Pálsdóttir, PhD student at the Center for ecological and evolutionary synthesis of the University of Oslo in Sweden .

"Since horses are so difficult to sex morphologically unless they are fairly well preserved, entire skeletons are found, we know very little about the different roles of male and female horses in the past," he said. Pálsdóttir.

Scientists turned to ancient DNA, or DNA, to reveal the sex of the horses, which they were able to achieve with small amounts of genetic material. They examined 22 horses from 17 sites and of the 19 horses found in graves, 18 were males. This suggests that the Viking nobles whose graves were common have promoted the ritual burial of male horses, Pálsdóttir said in the e-mail.

"The sex ratio and age distribution of the killed horses suggest that there was a well-formed structure behind the rituals in which the chosen horse acted as a symbolic representative," she explained.

"The conscious choice of the males may have been related to the characteristics of the stallions, and virility and aggressiveness could have been a powerful symbolic factor," Pálsdóttir added.

However, the remains of three horses found outside the tombs had not received the ceremonial treatment of buried horses. The authors of the study concluded that all these animals were females and that they had probably been eaten.

Upon further analysis of their samples, scientists will compare them to evidence showing that horses from other northern European countries date back to Viking age, explained Pálsdóttir to Live Science. They hope to find the geographical origins of Viking horses and physical characteristics such as the colors of horses, she added.

The results were published online in the January 2019 issue of the Journal of Archaeological Science.

Original article on Science live.