| 1. |
|
|
| 2. |
- Buntgen, U., et al.
(författare)
-
Tree rings reveal globally coherent signature of cosmogenic radiocarbon events in 774 and 993 CE
- 2018
-
Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 9
-
Tidskriftsartikel (refereegranskat)abstract
- Though tree-ring chronologies are annually resolved, their dating has never been independently validated at the global scale. Moreover, it is unknown if atmospheric radiocarbon enrichment events of cosmogenic origin leave spatiotemporally consistent fingerprints. Here we measure the 14C content in 484 individual tree rings formed in the periods 770–780 and 990–1000 CE. Distinct 14C excursions starting in the boreal summer of 774 and the boreal spring of 993 ensure the precise dating of 44 tree-ring records from five continents. We also identify a meridional decline of 11-year mean atmospheric radiocarbon concentrations across both hemispheres. Corroborated by historical eye-witness accounts of red auroras, our results suggest a global exposure to strong solar proton radiation. To improve understanding of the return frequency and intensity of past cosmic events, which is particularly important for assessing the potential threat of space weather on our society, further annually resolved 14C measurements are needed.
|
|
| 3. |
|
|
| 4. |
- Barrie, William, et al.
(författare)
-
Elevated genetic risk for multiple sclerosis emerged in steppe pastoralist populations
- 2024
-
Ingår i: NATURE. - 0028-0836 .- 1476-4687. ; 625:7994
-
Tidskriftsartikel (refereegranskat)abstract
- Multiple sclerosis (MS) is a neuro-inflammatory and neurodegenerative disease that is most prevalent in Northern Europe. Although it is known that inherited risk for MS is located within or in close proximity to immune-related genes, it is unknown when, where and how this genetic risk originated1. Here, by using a large ancient genome dataset from the Mesolithic period to the Bronze Age2, along with new Medieval and post-Medieval genomes, we show that the genetic risk for MS rose among pastoralists from the Pontic steppe and was brought into Europe by the Yamnaya-related migration approximately 5,000 years ago. We further show that these MS-associated immunogenetic variants underwent positive selection both within the steppe population and later in Europe, probably driven by pathogenic challenges coinciding with changes in diet, lifestyle and population density. This study highlights the critical importance of the Neolithic period and Bronze Age as determinants of modern immune responses and their subsequent effect on the risk of developing MS in a changing environment. Analysis of a large ancient genome dataset shows that genetic risk for multiple sclerosis rose in steppe pastoralists, providing insight into how genetic ancestry from the Neolithic and Bronze Age has shaped modern immune responses.
|
|
| 5. |
- Sikora, M., et al.
(författare)
-
The population history of northeastern Siberia since the Pleistocene
- 2019
-
Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 570:7760
-
Tidskriftsartikel (refereegranskat)abstract
- Northeastern Siberia has been inhabited by humans for more than 40,000 years but its deep population history remains poorly understood. Here we investigate the late Pleistocene population history of northeastern Siberia through analyses of 34 newly recovered ancient genomes that date to between 31,000 and 600 years ago. We document complex population dynamics during this period, including at least three major migration events: an initial peopling by a previously unknown Palaeolithic population of 'Ancient North Siberians' who are distantly related to early West Eurasian hunter-gatherers; the arrival of East Asian-related peoples, which gave rise to 'Ancient Palaeo-Siberians' who are closely related to contemporary communities from far-northeastern Siberia (such as the Koryaks), as well as Native Americans; and a Holocene migration of other East Asian-related peoples, who we name 'Neo-Siberians', and from whom many contemporary Siberians are descended. Each of these population expansions largely replaced the earlier inhabitants, and ultimately generated the mosaic genetic make-up of contemporary peoples who inhabit a vast area across northern Eurasia and the Americas.
|
|
