  We suggest that quintessential vacuum energy could be the source of right
handed neutrino masses that feed the seesaw mechanism, which may provide
observed small masses to light standard neutrinos. This idea is naturally
implemented in the Cosmological Unification model based on the global $SO(1,1)$
symmetry, where early inflation and late accelerated expansion of the Universe
are driven by the degrees of freedom of a doublet scalar field. In this model,
the $SO(1,1)$ custodial symmetry naturally provides the quintessence to
standard model singlet fermion couplings that source neutrino masses. We also
show that the model predicts a highly suppressed contribution to relativistic
degrees of freedom from quintessential quanta at any late Universe epoch,
ensuring the consistency of the model.
