Every individual has two parents, four grand-parents and so on. This would yield an astronomical number of ancestors even after a small number of generations, e.g. 235 ∼ 34 billions. The solution to this paradox is called pedigree collapse which takes into account that some of the ancestors in the binary Ahnentafel are identical, i.e. one and the same subject. This leads to a decrease of the number of ancestors of a given generation.
Are there any empirical statistics about the average number of ancestors of generation -1, -2, -3, etc. in a given population.
The average number of parents is exactly 2, the average number of grand-parents is slightly less than 4, and so on.
Which mathematical model might yield sensible numbers? Does anyone know a reference?