RT Journal Article
SR Electronic
T1 Dating ancient human samples using the recombination clock
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 023341
DO 10.1101/023341
A1 Priya Moorjani
A1 Sriram Sankararaman
A1 Qiaomei Fu
A1 Molly Przeworski
A1 Nick Patterson
A1 David Reich
YR 2015
UL http://biorxiv.org/content/early/2015/07/27/023341.abstract
AB The study of human evolution has been revolutionized by inferences from ancient DNA analyses. Key to these is the reliable estimation of the age of ancient specimens. The current best practice is radiocarbon dating, which relies on characterizing the decay of radioactive carbon isotope (14C), and is applicable for dating up to 50,000-year-old samples. Here, we introduce a new genetic method that uses recombination clock for dating. The key idea is that an ancient genome has evolved less than the genomes of extant individuals. Thus, given a molecular clock provided by the steady accumulation of recombination events, one can infer the age of the ancient genome based on the number of missing years of evolution. To implement this idea, we take advantage of the shared history of Neanderthal gene flow into non-Africans that occurred around 50,000 years ago. Using the Neanderthal ancestry decay patterns, we estimate the Neanderthal admixture time for both ancient and extant samples. The difference in these admixture dates then provides an estimate of the age of the ancient genome. We show that our method provides reliable results in simulations. We apply our method to date five ancient Eurasian genomes with radiocarbon dates ranging between 12,000 to 45,000 years and recover consistent age estimates. Our method provides a complementary approach for dating ancient human samples and is applicable to ancient non-African genomes with Neanderthal ancestry. Extensions of this methodology that use older shared events may be able to date ancient genomes that fall beyond the radiocarbon frontier.Significance We introduce a new genetic method for dating ancient human samples that uses the recombination clock. The main idea relies on the insight that an ancient genome lacks several thousand years of evolution compared to genomes of living individuals. To infer the age of ancient genomes, we take advantage of the shared history of Neanderthal gene flow into non-Africans that occurred around 50,000 years ago. By characterizing the dates of Neanderthal gene flow in ancient and extant genomes and quantifying the difference in these dates, we estimate the age of the ancient specimen. Our method is applicable for dating ancient samples more recent than the Neanderthal mixture event, so on par with radiocarbon dating, providing a complementary approach for dating.