  An evolutionary tree is a cascade of bifurcations starting from a single
common root, generating a growing set of daughter species as time goes by.
Species here is a general denomination for biological species, spoken languages
or any other entity evolving through heredity. From the N currently alive
species within a clade, distances are measured through pairwise comparisons
made by geneticists, linguists, etc. The larger is such a distance for a pair
of species, the older is their last common ancestor. The aim is to reconstruct
the past unknown bifurcations, i.e. the whole clade, from the knowledge of the
N(N-1)/2 quoted distances taken for granted. A mechanical method is presented,
and its applicability discussed.
