Two polymorphic Alu elements HS2.25 and HS4.14 belong to young human-specific Ya5/8 subfamily. HS2.25 and HS4.14 have long 3'-oligo-dA-rich tails of 41 and 52 nucleotides. Both Alu repeats show low random mutations. HS2.25 flanked by 8-nucleotide direct repeats. HS4.14 flanked by 14-nucleotide direct repeats. HS2.25 located on chromosome 13. HS4.14 located on chromosome 1. Both absent from orthologous positions in non-human primates. Both highly polymorphic in twelve geographically diverse human groups.