We are a group of archaeologists, anthropologists, curators and geneticists representing diverse global communities and 31 countries. All of us met in a virtual workshop dedicated to ethics in ancient DNA research held in November 2020. There was widespread agreement that globally applicable ethical guidelines are needed, but that recent recommendations grounded in discussion about research on human remains from North America are not always generalizable worldwide. Here we propose the following globally applicable guidelines, taking into consideration diverse contexts. These hold that: (1) researchers must ensure that all regulations were followed in the places where they work and from which the human remains derived; (2) researchers must prepare a detailed plan prior to beginning any study; (3)
The within-host evolutionary dynamics of tuberculosis (TB) remain unclear, and underlying biological characteristics render standard population genetic approaches based upon the Wright-Fisher model largely inappropriate. In addition, the compact genome combined with an absence of recombination is expected to result in strong purifying selection effects. Thus, it is imperative to establish a biologically relevant evolutionary framework incorporating these factors in order to enable an accurate study of this important human pathogen. Further, such a model is critical for inferring fundamental evolutionary parameters related to patient treatment, including mutation rates and the severity of infection bottlenecks. We here implement such a model and infer the underlying evolutionary parameters governing within-patient evolutionary dynamics. Results demonstrate that the progeny skew associated with the clonal nature of TB severely reduces genetic diversity and that the neglect of this parameter in previous studies has led to significant mis-inference of mutation rates. As such, our results suggest an underlying de novo mutation rate that is considerably faster than previously inferred, and a progeny distribution differing significantly from Wright-Fisher assumptions.This inference represents a more appropriate evolutionary null model, against which the periodic effects of positive selection, associated with drug-resistance for example, may be better assessed. K E Y W O R D S : Mutation rate, population bottleneck, population genetics, progeny-skew, tuberculosis, Wright-Fisher model.
The northern and southern peripheries of ancient Mesoamerica are poorly understood. There has been speculation over whether borderland cultures such as Greater Nicoya and Casas Grandes represent Mesoamerican outposts in the Isthmo-Colombian area and the Greater Southwest, respectively. Poor ancient DNA preservation in these regions challenged previous attempts to resolve these questions using conventional genetic techniques. We apply advanced in-solution mitogenome capture and high-throughput sequencing to fourteen dental samples obtained from the Greater Nicoya sites of Jícaro and La Cascabel in northwest Costa Rica (n = 9; A.D. 800–1250) and the Casas Grandes sites of Paquimé and Convento in northwest Mexico (n = 5; A.D. 1200–1450). Full mitogenome reconstruction was successful for three individuals from Jícaro and five individuals from Paquimé and Convento. The three Jícaro individuals belong to haplogroup B2d, a haplogroup found today only among Central American Chibchan-speakers. The five Paquimé and Convento individuals belong to haplogroups C1c1a, C1c5, B2f and B2a which, are found in contemporary populations in North America and Mesoamerica. We report the first successfully reconstructed ancient mitogenomes from Central America, and the first genetic evidence of ancestry affinity of the ancient inhabitants of Greater Nicoya and Casas Grandes with contemporary Isthmo-Columbian and Greater Southwest populations, respectively.
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