The first-ever genome-wide DNA analysis of ancient Sardinian’s has revealed new insights into historical mysteries of the past as well as the genetic secrets of some of the longest-living peoples in the word.
Sardinia, an Italian island in the Mediterranean Sea, boasts a unique history, having been inhabited since the Paleolithic. The island has one of the highest rates of people who live to 100 years or more while they also have higher-than-average rates of autoimmune diseases and disorders, such as beta-thalassemia and G6PD deficiency.
To uncover genetic variants that may be linked to disease and aging, a research team led by professors from the University of Chicago and Max Planck analyzed the ancient DNA of 70 individuals from more than 20 Sardinian archaeological sites spanning roughly 6,000 years, from the Middle Neolithic through the Medieval period. The team discovered major population patterns that help explain the unique genetics of the island then, now and possibly in the future.
First, they saw that Sardinian individuals in the Middle Neolithic period (4100-3500 BCE) were closely related to people from mainland Europe of the time. Genetic ancestry then remained relatively stable on the island through at least the end of the Nuragic period (~900 BCE). Next, the team found evidence of the arrival of different populations across the Mediterranean, first with Phoenicians originating from the Levant (modern-day Lebanon) and Punics, whose culture centered in Carthage (modern-day Tunisia). Then, new ancestry continued to appear during the Roman period and further in the Medieval period, as Sardinia became historically influenced by migration of people from modern-day Italy and Spain.
The stability in ancestry from the Middle Neolithic period through the end of the Nuragic was one of the most striking discoveries of the study, published in Nature Communications. The pattern differs from most other regions of mainland Europe that saw a major uptick in new ancestries as people migrated across the continent in the Bronze Age.
This unexpected pattern explains the mystery of why the DNA of the infamous Ötzi the Iceman is most similar to modern-day Sardinians, as opposed to modern-day Europeans. Sardinia simply had less turnover of genetic ancestry over time than mainland Europe.
“For future studies, we want to look more precisely at mutations that we think are involved in disease to see in which period they changed in frequency and how quickly they changed,” said senior author John Novembre, a computational biologist at the University of Chicago. “That will help us understand the processes acting on these diseases, and in turn gain a richer view that may yield insights for human health.”
The genetic makeup of ancient Sardinians was not the only unique element of this study. The research was conducted across an international interdisciplinary team comprised of geneticists, archeologists, biologists, archaeogeneticists, data analysts and more. In fact, there are 38 authors listed in the Nature Communications paper from multiple states in the United States, Germany and Italy.
Photo: The town of Seulo, Sardinia, around which there are several cave archaeological sites that have been excavated by study co-authors Maria Giuseppina Gradoli, Robin Skeates, and Jessica Becket and from which samples were collected for the study. Credit: John Novembre/UChicago