Human Y Chromosome
In humans, the Y chromosome spans about 58 million base pairs (the building blocks of DNA) and represents approximately 2% of the total DNA in a male cell. The human Y chromosome contains 86 genes, which code for only 23 distinct proteins. Traits that are inherited via the Y chromosome are called holandric traits.
The human Y chromosome is unable to recombine with the X chromosome, except for small pieces of pseudoautosomal regions at the telomeres (which comprise about 5% of the chromosome's length). These regions are relics of ancient homology between the X and Y chromosomes. The bulk of the Y chromosome which does not recombine is called the "NRY" or non-recombining region of the Y chromosome. It is the SNPs (single-nucleotide polymorphism) in this region which are used for tracing direct paternal ancestral lines.
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“We become male automatically because of the Y chromosome and the little magic peanut, but if we are to become men we need the help of other men—we need our fathers to model for us and then to anoint us, we need our buddies to share the coming-of-age rituals with us and to let us join the team of men, and we need myths of heroes to inspire us and to show us the way.”
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