christian online dating nova scotia - Other methods of anthropological dating
Here, we describe a genetic approach for dating ancient samples, applicable in cases where DNA sequence data are available, as is becoming increasingly common (1).This method relies on the insight that an ancient genome has experienced fewer generations of evolution compared with the genomes of its living (i.e., extant) relatives.
(6), who used the mutation clock (instead of the recombination clock as proposed here) to estimate the age of the Denisova finger bone, which is probably older than 50,000 y, and has not been successfully radiocarbon dated (6).
Specifically, the authors compared the divergence between the Denisova and extant humans and calibrated the branch shortening relative to human–chimpanzee (HC) divergence time.
High-resolution age estimates can often be obtained using radiocarbon dating, and, while precise and powerful, this method has some biases, making it of interest to directly use genetic data to infer a date for samples that have been sequenced.
Here, we report a genetic method that uses the recombination clock.
The idea is that an ancient genome has evolved less than the genomes of present-day individuals and thus has experienced fewer recombination events since the common ancestor.
To implement this idea, we take advantage of the insight that all non-Africans have a common heritage of Neanderthal gene flow into their ancestors.
In addition, comparison with HC divergence relies on branch-shortening estimates that are small relative to the total divergence of millions of years, so that even very low error rates in allele detection can bias estimates.
These issues lead to substantial uncertainty in estimated age of the ancient samples, making this approach impractical for dating specimens that are tens of thousands of years old, a time period that encompasses the vast majority of ancient human samples sequenced to date.
The use of ape divergence time for calibration, however, relies on estimates of mutation rate that are uncertain (7).
In particular, recent pedigree studies have yielded a yearly mutation rate that is approximately twofold lower than the one obtained from phylogenetic methods (7).
Extensions of this methodology that use older shared events may be applicable for dating beyond the radiocarbon frontier.Tags: Adult Dating, affair dating, sex dating