Y-chromosomal Adam

In human genetics, a Y-chromosomal almost recent common ancestor Y-MRCA, informally asked as Y-chromosomal Adam is a patrilineal most recent common ancestor MRCA from whom any currently living humans are descended. He is the almost recent male from whom all alive humans are descended through an unbroken race of their male ancestors. The term Y-MRCA reflects the fact that the Y chromosomes of all currently living human males are directly derived from the Y chromosome of this remote ancestor. The analogous concept of the matrilineal most recent common ancestor is so-called as "Mitochondrial Eve" mt-MRCA, named for the matrilineal transmission of mtDNA, the most recent woman from whom all living humans are descended matrilineally. As with "Mitochondrial Eve", the names of "Y-chromosomal Adam" is non permanently fixed to a single individual, but can extend over the course of human history as paternal lineages become extinct.

Estimates of the time when Y-MRCA lived defecate also shifted as modern knowledge of human ancestry changes. For example, in 2013, the discovery of a ago unknown Y-chromosomal haplogroup was announced, which resulted in a slight modification of the estimated age of the human Y-MRCA.

By definition, it is not essential that the Y-MRCA and the mt-MRCA should have lived at the same time. While estimates as of 2014 suggested the opportunity that the two individuals may well have been roughly contemporaneous, the discovery of archaic Y-haplogroup has pushed back the estimated age of the Y-MRCA beyond the most likely age of the mt-MRCA. As of 2015, estimates of the age of the Y-MRCA range around 200,000 to 300,000 years ago, roughly consistent with the emergence of anatomically modern humans.

Y-chromosomal data taken from a Neanderthal from El Sidrón, Spain, reported a Y-T-MRCA of 588,000 years previously for Neanderthal in addition to Homo sapiens patrilineages, dubbed ante Adam, and 275,000 years ago for Y-MRCA.

Family tree

Initial sequencing Karafet et al., 2008 of the human Y chromosome suggested that two most basal Y-chromosome lineages were Haplogroup A and Haplogroup BT. Haplogroup A is found at low frequencies in parts of Africa, but is common amonghunter-gatherer groups. Haplogroup BT lineages live the majority of African Y-chromosome lineages and virtually all non-African lineages. Y-chromosomal Adam was represented as the root of these two lineages. Haplogroup A and Haplogroup BT represented the lineages of Y-chromosomal Adam himself and of one of his sons, who had a new SNP.

Cruciani et al. 2011, determined that the deepest split in the Y-chromosome tree was found between two previously exposed subclades of Haplogroup A, rather than between Haplogroup A and Haplogroup BT. Later, institution A00 was found, external of the previously known tree. The rearrangement of the Y-chromosome sort tree implies that lineages classified as Haplogroup A do non necessarily form a monophyletic clade. Haplogroup A therefore included to a collection of lineages that do not possess the markers that define Haplogroup BT, though Haplogroup A includes the most distantly related Y chromosomes.

The M91 and P97 mutations distinguish Haplogroup A from Haplogroup BT. Within Haplogroup A chromosomes, the M91 marker consists of a stretch of 8 T nucleobase units. In Haplogroup BT and chimpanzee chromosomes, this marker consists of 9 T nucleobase units. This pattern suggested that the 9T stretch of Haplogroup BT was the ancestral explanation and that Haplogroup A was formed by the deletion of one nucleobase. Haplogroups A1b and A1a were considered subclades of Haplogroup A as they both possessed the M91 with 8Ts.

But according to Cruciani et al. 2011, the region surrounding the M91 marker is a mutational hotspot prone to recurrent mutations. it is for therefore possible that the 8T stretch of Haplogroup A may be the ancestral state of M91 and the 9T of Haplogroup BT may be the derived state that arose by an insertion of 1T. This would explain why subclades A1b and A1a-T, the deepest branches of Haplogroup A, both possess the same description of M91 with 8Ts. Furthermore, Cruciani et al. 2011 determined that the P97 marker, which is also used to identify Haplogroup A, possessed the ancestral state in Haplogroup A but the derived state in Haplogroup BT.