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Human Y-chromosome DNA haplogroup
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Human Y-chromosome DNA haplogroup
In human genetics, a human Y-chromosome DNA haplogroup is a haplogroup defined by specific mutations in the non-recombining portions of DNA on the male-specific Y chromosome (Y-DNA). Individuals within a haplogroup share similar numbers of short tandem repeats (STRs) and single-nucleotide polymorphisms (SNPs). The Y-chromosome accumulates approximately two mutations per generation, and Y-DNA haplogroups represent significant branches of the Y-chromosome phylogenetic tree, each characterized by hundreds or even thousands of unique mutations.
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[citation needed]. 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). Although Southeast Asia has been proposed as the origin for all non-African human Y chromosomes, this hypothesis is considered unlikely. 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).
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.
Phylogenetic tree of Y-DNA haplogroups
Haplogroup A is the NRY (non-recombining Y) macrohaplogroup from which all modern paternal haplogroups descend. It is sparsely distributed in Africa, being concentrated among Khoisan populations in the southwest and Nilotic populations toward the northeast in the Nile Valley. BT is a subclade of haplogroup A, more precisely of the A1b clade (A2-T in Cruciani et al. 2011), as follows:
The defining mutations separating CT (all haplogroups except for A and B) are M168 and M294. The site of origin is likely in Africa. Its age has been estimated at approximately 88,000 years old, and more recently at around 100,000 or 101,000 years old.
The groups descending from haplogroup F are found in some 90% of the world's population, but almost exclusively outside of sub-Saharan Africa.
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Human Y-chromosome DNA haplogroup
In human genetics, a human Y-chromosome DNA haplogroup is a haplogroup defined by specific mutations in the non-recombining portions of DNA on the male-specific Y chromosome (Y-DNA). Individuals within a haplogroup share similar numbers of short tandem repeats (STRs) and single-nucleotide polymorphisms (SNPs). The Y-chromosome accumulates approximately two mutations per generation, and Y-DNA haplogroups represent significant branches of the Y-chromosome phylogenetic tree, each characterized by hundreds or even thousands of unique mutations.
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[citation needed]. 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). Although Southeast Asia has been proposed as the origin for all non-African human Y chromosomes, this hypothesis is considered unlikely. 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).
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.
Phylogenetic tree of Y-DNA haplogroups
Haplogroup A is the NRY (non-recombining Y) macrohaplogroup from which all modern paternal haplogroups descend. It is sparsely distributed in Africa, being concentrated among Khoisan populations in the southwest and Nilotic populations toward the northeast in the Nile Valley. BT is a subclade of haplogroup A, more precisely of the A1b clade (A2-T in Cruciani et al. 2011), as follows:
The defining mutations separating CT (all haplogroups except for A and B) are M168 and M294. The site of origin is likely in Africa. Its age has been estimated at approximately 88,000 years old, and more recently at around 100,000 or 101,000 years old.
The groups descending from haplogroup F are found in some 90% of the world's population, but almost exclusively outside of sub-Saharan Africa.
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