Sequences Human LCA was 143,000 ya 180,000 yrs. African sequence most divergent. Human-Chimp divergence at 4.9my assuming African Apes and Organgutans began diverging 13 mya. Alu loci in 1500 individuals from 34 worldwide populations. The effective population size of humans throughout history has an effect on some kinds of estimates about the time to a common ancestor for DNA sequences of living humans.
Drift acts more strongly in smaller pops.
Effective Population Size Ne for modern humans is 10,000 adults or less. It is possible to estimate when populations began expanding by looking at the distribution of pairwise mutational differences between all pairs of individuals within a population. Mismatch distributions This number applied to most human pops indicates an expansion between 40-60 kya.