The genealogies of a population reflect population events of the past.
We define lineal admixture time per lineage. This measure in time duration depends on two reference time points:
a past time horizon when all ancestors are members of separate non-admixed subpopulations, and
an observation time, such as the present.
Given a lineage, the lineal admixture time is defined as:
the amount of time since fertilization of the first admixed individual in the lineage.