We investigate a network growth model in which the genealogy controls the evolution. In this model, a new node selects a random target node and links either to this target node, or to its parent, or to its grandparent, etc; all nodes from the target node to its most ancient ancestor are equiprobable destinations. The emerging random ancestor tree is very shallow: the fraction g_n of nodes at distance n from the root decreases super-exponentially with n, g_n=e^{ -1}/(n-1)!. We find that a macroscopic hub at the root coexists with highly connected nodes at higher generations. The maximal degree of a node at the nth generation grows algebraically as N^{ 1/beta_n} where N is the system size. We obtain the series of nontrivial exponents which are roots of transcendental equations: beta_1= 1.351746, beta_2=1.682201, etc. As a consequence, the fraction p_k of nodes with degree k has algebraic tail, p_k ~ k^{ -gamma}, with gamma=beta_1+1=2.351746.
Categories: cond-mat.stat-mech math.PR physics.data-an physics.soc-ph