Researchers from the Francis Crick Institute and University of York have made a breakthrough in identifying the earliest cases of genetic disorders affecting sex chromosomes. The findings of their study have been published in the scientific journal Communications Biology.
Human DNA consists of pairs of chromosomes, with the sex chromosomes named X and Y. Typically, females have two X chromosomes (XX) and males have one X and one Y chromosome (XY). Abnormalities in these sex chromosomes can lead to developmental delays or changes in height during puberty.
The team from the Francis Crick Institute developed a new technique to accurately measure the number of chromosomes in ancient genomes. They applied this method to ancient human remains found during archaeological investigations conducted by Oxford Archaeology and its partners at Magdalen College in Oxford and the Trinity Burial Ground in Hull.
Using this technique, the researchers identified several ancient individuals with different genetic disorders. They found an infant from the Iron Age with Down’s Syndrome, who had three copies of chromosome 21 instead of two. This is the earliest known case of this disorder.
The team also discovered the oldest recorded case of mosaic Turner syndrome, a disorder where one of the X chromosomes in a female is either missing or partially missing, dating back 2,500 years. In addition, they found the earliest known person with Jacob’s syndrome, characterized by an extra Y chromosome (XYY), from the Early Medieval Period. Furthermore, three individuals with Klinefelter syndrome, where males have an extra X chromosome (XXY), were identified across various time periods.
This research not only sheds light on the ancient origins of these genetic disorders but also offers insight into how perceptions of gender identity have changed over time. By analyzing ancient DNA, scientists can move beyond binary categories and broaden our understanding of sex and gender in the past.
Rick Schulting, Professor of Scientific and Prehistoric Archaeology at the University of Oxford, believes that these findings open up new opportunities for the study of sex in ancient civilizations. He highlights the importance of advances in ancient DNA analysis, which allow researchers to explore gender identities beyond traditional binary classifications.
This groundbreaking research paves the way for further exploration of the genetic history of sex chromosomes and their impact on ancient societies. It also contributes to our understanding of the diversity of human genetic disorders and their origins.