Improved Models of Coalescence Ages of Y-DNA Haplogroups.

Iain Mcdonald

doi:10.3390/genes12060862

Abstract

Databases of commercial DNA-testing companies now contain more customers with sequenced DNA than any completed academic study, leading to growing interest from academic and forensic entities. An important result for both these entities and the test takers themselves is how closely two individuals are related in time, as calculated through one or more molecular clocks. For Y-DNA, existing interpretations of these clocks are insufficiently accurate to usefully measure relatedness in historic times. In this article, I update the methods used to calculate coalescence ages (times to most-recent common ancestor, or TMRCAs) using a new, probabilistic statistical model that includes Y-SNP, Y-STR and ancilliary historical data, and provide examples of its use.

Highlights

The human Y-DNA phylogenic tree is a uniquely written history of human relatedness and migration
We presume that all individuals concerned have taken a modern commercial Y-DNA sequencing test, variations of which are offered by multiple companies, which includes testing of 111 Y-short tandem repeats (STRs), each of which have a useable mutation rate
As a larger portion of tests become dominated by various longer tests of ∼13.5 million base pairs (Mbp) of usable coverage, the uncertainty will be reduced by ∼17% further in a haplogroup of similar size, age and structure

Summary

Introduction

The human Y-DNA phylogenic tree is a uniquely written history of human relatedness and migration. Tests are commercially sold to trace the social and migratory history of patrilineal surnames. This can help connect individuals studying shared surname history, identify a misattributed parent or a birth father, or provide an identity to human remains. In sufficiently widely tested haplogroups, this provides the haplogroup’s progenitor, the most-recent ancestor from whom all living men in that haplogroup are descended. In archaeology, such exploration of Y-DNA relationships can be used to reconstruct relatedness and migration during periods where ancient DNA cannot be sampled, e.g., because of the practice of cremation

Methods

Results

Conclusion