We consider the problem of finding the initial vertex (Adam) in a
Barab\'asi--Albert tree process (T(n):n≥1) at large times.
More precisely, given ε>0, one wants to output a subset Pε​(n) of vertices of T(n) so that the
initial vertex belongs to Pε​(n) with probability at
least 1−ε when n is large. It has been shown by Bubeck, Devroye
& Lugosi, refined later by Banerjee & Huang, that one needs to output at least
ε−1+o(1) and at most ε−2+o(1) vertices to
succeed. We prove that the exponent in the lower bound is sharp and the key
idea is that Adam is either a ``large degree" vertex or is a neighbor of a
``large degree" vertex (Eve).Comment: 11 pages, comments are welcome