Mitochondrial DNA signifies that nearly all modern dogs drop into a person of four monophyletic haplogroups which can be named haplogroups A, B, C, and D. Nearly all dogs tumble in haplogroup A. The mDNA "molecular clock" suggests that 22,800 YBP the very first genetic divergence (break up) occurred in haplogroup A, causing the lineages A1b and A2.