Y chromosome
Women and men have 23 pairs of chromosomes. From each pair, one is inherited from the father and one from the mother. Unlike autosomal chromosomes, named in order from "1" to "22", the two "sex" chromosomes have letter designations. XX in women and XY in men. From the mother, it is always the X chromosome. From the father, the child inherits either an X chromosome (girl) or a Y chromosome (boy). The X chromosome from the father turns into a combination of XX — and this is female sex. The Y chromosome from the father turns into a combination of XY and determines male sex. Almost all chromosomes undergo mixing (recombination) — a process in which each pair of chromosomes exchanges various fragments with each other. Since every man has only one Y chromosome, unlike the X chromosome, it does not recombine. For these reasons, genealogical analysis of X chromosomes is much more complicated. We also inherit mitochondrial DNA (mtDNA) from the mother, and none from the father.
The main tools of DNA genealogy are the analysis of mutations, their number and location in mtDNA and Y chromosomes. The Y chromosome, due to its very low mutation rate and the absence of mixing (recombination), unlike mitochondrial DNA, is passed down almost unchanged from generation to generation. Based on variations in mutations, chromosomes are divided into haplotypes, which are grouped into haplogroups and subclades (subgroups). The letter designations of haplogroups follow the alphabet and indicate the time of the appearance of the next mutation. That is, haplogroup A (the Y chromosome of the so-called Adam, which appeared about 75,000 years ago, is located today mainly in South Africa) is older than haplogroup G (about 30,000 years ago), and so on alphabetically.
Predicted distribution of Y-DNA haplogroups in 2000 BC
Distribution of Y-DNA haplogroups
Distribution of Y-DNA haplogroups in Europe
Migrations of Y-DNA haplogroups
Y-DNA haplogroup tree
Age of Y-DNA haplogroups. Maciamo Hay
Age of Y-DNA haplogroups