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Human Y-chromosome DNA haplogroup

Human DNA groupings

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The Y-chromosomal most recent common ancestor (Y-MRCA), often referred to as Y-chromosomal Adam, is the most recent common ancestor from whom all currently living humans are descended patrilineally. Y-chromosomal Adam is estimated to have lived around 236,000 years ago in Africa. By examining other population bottlenecks, most Eurasian men trace their descent from a man who lived in Africa approximately 69,000 years ago (Haplogroup CT). One study has suggested that Southeast Asia is the geographic origin for all non-African human Y chromosomes, however another study has disputed this due to the region being outside the possible range for admixture between Neanderthals and modern humans. Other bottlenecks occurred roughly 50,000 and 5,000 years ago, and the majority of Eurasian men are believed to be descended from four ancestors who lived 50,000 years ago, all of whom were descendants of an African lineage (Haplogroup E-M168).

Naming convention

Y-DNA haplogroups are defined by the presence of a series of Y-DNA single-nucleotide polymorphisms genetic markers. Subclades are defined by a terminal SNP, the SNP furthest down in the Y-chromosome phylogenetic tree. The Y Chromosome Consortium (YCC) developed a system of naming major Y-DNA haplogroups with the capital letters A through T, with further subclades named using numbers and lower case letters (YCC longhand nomenclature). YCC shorthand nomenclature names Y-DNA haplogroups and their subclades with the first letter of the major Y-DNA haplogroup followed by a dash and the name of the defining terminal SNP.

Y-DNA haplogroup nomenclature is changing over time to accommodate the increasing number of SNPs being discovered and tested, and the resulting expansion of the Y-chromosome phylogenetic tree. This change in nomenclature has resulted in inconsistent nomenclature being used in different sources. This inconsistency, and increasingly cumbersome longhand nomenclature, has prompted a move toward using the simpler shorthand nomenclature.

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GenusTaxonomic rank above species and below familyFamily (taxonomy)Taxonomic rank between genus and orderEndemismState of species being unique to a locationCladeGroup of a common ancestor and all of their descendantsGenomeAll genetic material of an organismOrder (taxonomy)Taxonomic rank between class and family