  In a randomly-mating biparental population of size $N$ there are, with high
probability, individuals who are genealogical ancestors of every extant
individual within approximately $\log_2(N)$ generations into the past. We use
this result of J. Chang to prove a curious corollary under standard models of
recombination: there exist, with high probability, individuals within a
constant multiple of $ \log_2(N)$ generations into the past who are
simultaneously (i) genealogical ancestors of {\em each} of the individuals at
the present, and (ii) genetic ancestors to {\em none} of the individuals at the
present. Such ancestral individuals - ancestors of everyone today that left no
genetic trace -- represent `ghost' ancestors in a strong sense. In this short
note, we use simple analytical argument and simulations to estimate how many
such individuals exist in finite Wright-Fisher populations.
