We have analysed a linked microsatellite/Alu polymorphism at the CD4 locus (CD4/Alu) in 666
chromosomes from samples of the Iberian Peninsula, Northwest Africa, and West sub-Saharan
Africa. The Iberian Peninsula differs from other European populations by its higher levels of
haplotype diversity (0.75), and weaker association between the microsatellite allele 90 and Alu(−)
chromosomes. These results are explainable by a substantial gene flow from Northwest Africa.
Significant geographic clines for the five major haplotypes suggest a south to north migration from
sub-Saharan Africa into Northwest Africa. In spite of this, the consistent presence of haplotype
110(−) in this area is congruent with an ancient and autochthonous human presence in Northwest
Africa.