A recent insertion of an alu element on the Y chromosome is a useful marker for human population studies.

A member of the Alu family of repeated DNA elements has been identified on the long arm of the human Y chromosome, Yq11. This element, referred to as the Y Alu polymorphic (YAP) element, is present at a specific site on the Y chromosome in some humans and is absent in others. Phylogenetic comparisons with other Alu sequences reveal that the YAP element is a member of the polymorphic subfamily-3 (PSF-3), a previously undefined subfamily of Alu elements. The evolutionary relationships of PSF-3 to other Alu subfamilies support the hypothesis that recently inserted elements result from multiple source genes. The frequency of the YAP element is described in 340 individuals from 14 populations, and the data are combined with those from other populations. There is both significant heterogeneity among populations and a clear pattern in the frequencies of the insertion: sub-Saharan Africans have the highest frequencies, followed by northern Africans, Europeans, Oceanians, and Asians. An interesting exception is the relatively high frequency of the YAP element in Japanese. The greatest genetic distance is observed between the African and non-African populations. The YAP is especially useful for studying human population history from the perspective of male lineages.