The existence of human twins in the past is not unheard of. However, finding relatively well-preserved skeletons of a pair of infant twins from thousands of years ago is nothing short of fascinating. An international team of scientists has discovered a burial site from 31,000 years ago, and in it, the world's oldest known buried remains of identical twins.

According to the team of multi-disciplinary researchers, the grave belongs to the Upper Paleolithic period—which lasted from 40,000 to 10,000 years ago—that is commonly known as the Old Stone Age. In the burial site, the scientists found not only remnants of the two twins, but also a third infant, who is most likely a cousin.

Infant double burial
Infant double burial in Krems am Wachtberg OREA OeAW

"To discover a multiple burial from the Paleolithic period is a specialty in itself. The fact that sufficient and high-quality old DNA could be extracted from the fragile, child's skeletal remains for a genome analysis exceeded all of our expectations and can be compared to a lottery ticket," said, Maria Teschler-Nicola, lead researcher of the study, in a statement.

Together In Death

The oval-shaped grave of the twins was located at an archaeological dig in Krems-Wachtberg, an ancient settlement, along the banks of the Danube River near the town center of Krems an der Donau, Austria in 2005. Found covered in ochre— an earthy pigment consisting of ferric oxide that was used in burials in ancient times—were the mortal remains of the two babies.

Excavation of the double burials
Excavation of the double burials in Krems am Wachtberg OREA OeAW

In order to confirm the relationship between the infants, the archeologists conducted a genomic analysis of the ancient DNA. The examination led the authors to conclude that that two were not just twins, but identical twins. Also, the third baby, believed to be around 3-months-old and buried around 1.5 meters (5 feet) from where the twins were laid to rest, was possibly a cousin.

Another interesting aspect of the finding was that the twin, who lived for a few weeks longer than his brother, was reburied along with him after his demise. Therefore, reopening of the grave would have been required for the "reburial". This confirms a newly uncovered cultural-historical phenomenon of opening graves for re-interring corpses—something that was not known for the Paleolithic period.

Buried With 'Treasures'

Ornaments In The Grave
The bodies of the twins in the grave pit, mammoth ivory pearls and their arrangement on the basin, ornamentation consisting of a perforated fox incisor and three perforated mollusks OREA-OeAW

The twins were not buried without any treasures. Unearthed in the graves of the brothers were 53 beads fashioned out of mammoth ivory which were probably strung on a thread like a necklace. Along with the beads, a pierced fox incisor and three perforated mollusks, which were likely pendants on a necklace, were also found according to the study. Protecting the infant bodies from the elements above, a mammoth shoulder blade had been placed over their bodies.

Their supposed cousin, who was buried not far from them, was also smeared in ochre. In his possession was a mammoth-ivory pin measuring 8 centimeters (3 inches), which might have been used to hold a leather garment in place during the burial, explained the researchers.

Life, Struggles and Death

Infant double burial
Infant double burial in Krems am Wachtberg OREA OeAW

While the genetic analysis revealed the relationship between the three ancient remains, a scrutiny of the upper lateral deciduous incisors aided the researchers in pinpointing their age. The authors focused on the "newborn line or neonatal line (NNL)—a dark line on the tooth enamel which separates enamel that was formed prenatally from the enamel formed post-birth.

The NNL, along with the skeletal structures suggested that the brothers completed nearly-full or full term, and belonged to a hunter-gatherer group. Upon chemical analysis of several elements in the tooth enamel, including isotopes such as barium, carbon, and nitrogen, it was learnt that the twins had been breastfed. The authors posited that one of the babies died not long after birth, while his twin brother survived only for 6-7 weeks. The cause of their death, however, is yet to be ascertained.

Replica of the double burial
Replica of the double burial in room 14 of the NHM Vienna NHM Vienna, Kurt Kracher

Though their cousin lived for three months, the "stress lines" on his teeth indicate that he was marred by feeding difficulties. This probably was because his mother struggled from mastitis—a painful infection of the breast—or succumbed during childbirth. According to the authors, the early deaths of the babies is perhaps a reflection of a lean phase of food supply among the Paleolithic hunter-gatherer group who settled in the area 30,000 years ago.