DNA analysis of an Upper Palaeolithic tomb containing the remains of two newborn babies has revealed that they were identical twins. This is the first known example of monozygotic twins confirmed by analysis of their ancient DNA.
Found at the Krems-Wachtberg burial in Austria, the twins were found alongside a 3-month-old baby who was a third-degree male relative, possibly a first cousin.
Finding remains from this historical moment is extremely rare, so finding up to three individuals in an early stage will offer us new data on the burial practices of the first humans, as it is a unique and significant discovery.
According to the study, reported in the journal Nature , organic materials have been preserved particularly well in the sediment.
To assess the sexual and biological relationships of the three individuals, the team of archaeologists took samples from each of the skulls and found that they shared the same main Y chromosome and mitochondrial haplogroups: the twins shared their entire genome.
The age of death was determined by the length of the bones and the stages of dental development. The twins’ teeth showed enamel deterioration, but it was possible to obtain a more accurate estimate of age by measuring the length of the enamel prism with a CT scan. The researchers found that one of the baby boys lived for six to seven weeks after birth and the other for 13 to 14 weeks after delivery.
After the babies were placed in the grave, it was not filled with dirt, but instead sealed with the shoulder blade of a mammoth that revealed signs of having been chipped with a tool. Their results revealed that the twins were full-term newborns, marking the first known example of monozygotic twins as their DNA was identical.
A third baby was also found in a longer and narrower second fossa at the site. This tomb was filled with earth instead of sealing it with a protective plate, which showed that the body was poorly preserved compared to the twins from the first tomb.
Referencia: Teschler-Nicola, M., Fernandes, D., Händel, M. et al. Ancient DNA reveals monozygotic newborn twins from the Upper Palaeolithic. Commun Biol 3, 650 (2020). https://doi.org/10.1038/s42003-020-01372-8
