  We review the similarities between the effective chiral lagrangrian, relevant
for low-energy strong interactions, and the Einstein-Hilbert action. We use
these analogies to suggest a specific mechanism whereby gravitons would emerge
as Goldstone bosons of a global SO(D) X GL(D) symmetry broken down to SO(D) by
fermion condensation. We propose a two-dimensional toy model where a dynamical
zwei-bein is generated from a topological theory without any pre-existing
metric structure, the space being endowed only with an affine connection. A
metric appears only after the symmetry breaking; thus the notion of distance is
an induced effective one. In spite of several non-standard features this simple
toy model appears to be renormalizable and at long distances is described by an
effective lagrangian that corresponds to that of two-dimensional gravity
(Liouville theory). The induced cosmological constant is related to the
dynamical mass M acquired by the fermion fields in the breaking, which also
acts as an infrared regulator. The low-energy expansion is valid for momenta k
>M, i.e. for supra-horizon scales. We briefly discuss a possible implementation
of a similar mechanism in four dimensions.
