The woman was discovered in 2010 in a cave known as El Mirón, where humans are known to have sheltered from the cold during the Pleistocene epoch's last glacial period – more commonly referred to as the Ice Age.
She is estimated to have been between 35 and 40-years-old at the time of her death, around 19,000 years ago. The circumstances of her passing still puzzle archaeologists, even after five years of investigations.
Analysis of her bones suggests that she had been in good health, with a diet consisting mainly of deer, fish and mushrooms, and the reason for her death is unknown.
According to Spanish daily El Pais, the woman was left to decompose in the open air then her skeleton was painted with red ochre before being buried. This red paint was difficult to manufacture because it required iron oxide not found in the area, suggesting that a special effort was made.
The archaeologists in charge of the dig, Lawrence Straus of the University of New Mexico and Manuel González Morales of Cantabria University, believe that the woman's unusual burial may have been ceremonial.
"But what her role was, we do not have a clue," Straus told Live Science website.
As a result of the colouring, Straus and González have nicknamed her 'The Red Lady'. She shares the title with another famous red-painted skeleton, the 33,000-year-old Red Lady of Paviland found in Wales, which was eventually revealed to be the bones of a young man.
The Red Lady of Cantabria has not lain undisturbed for 19,000 years; her thigh bone shows signs of having been chewed by a dog or a wolf then re-buried. Other bones, including her skull, are missing, and were probably moved to another site for religious reasons.
El Mirón cave was explored by archaeologists between 2006 and 2010. They found a large limestone block that had fallen from the ceiling. It was marked with triangular symbols that archaeologists think may represent the female vulva. Behind the block, they discovered more than 100 bones belonging to the Red Lady.
González emphasized that it was extraordinary to find such old human remains."They are very rare and are concentrated in an even older period, from 28,000 years ago. After that there’s almost nothing until about 19,000 years ago, but even then there are very few: half-a-dozen in France and, until this discovery, none in the Iberian peninsula," he said.
"We don’t know what people of that time did with their dead, but in a few cases they were buried in caves," he added.
González Morales’s findings are to be published this month in a special edition of the Journal of Archaeological Science.