Mitochondrial DNA suggests that almost all modern dogs tumble into a single of 4 monophyletic haplogroups which can be named haplogroups A, B, C, and D. Nearly all dogs slide in just haplogroup A. The mDNA "molecular clock" signifies that 22,800 YBP the main genetic divergence (split) happened in haplogroup A, resulting in the lineages A1b and A2.