Figure 5. Model of chromosomal 15q13.3 evolution.

Based on comparisons to outgroup primates, we propose a simpler human ancestral organization (Hα₁)—a configuration that is found enriched in contemporary African populations. A 510 kbp duplicative transposition from BP5 to BP4 (α and β duplications) occurred potentially in a palindromic configuration (Hα₂), followed by an inversion of β at BP4 (Hα₂β_inv) between 700–900 thousand years ago. NAHR within BP5 leads to tandemization of the 510 kbp duplication (Hα₃) and larger configurations primarily in East Asian populations. Approximately 500 thousand years ago, the 1.8 Mbp γ inversion independently rearranged to the Hα₁γ_inv inverted haplotype.