  The explanation of various observed phenomena such as large angle neutrino
oscillations, hierarchies of charged fermion masses and CKM mixings, and
apparent baryon number conservation may have a common origin. We show how this
could occur in 5D SUSY SU(5) supplemented by a ${\cal U}(1)$ flavor symmetry
and additional matter supermultiplets called 'copies'. In addition, the proton
decays into $p\to K\nu $, with an estimated lifetime of order $10^{33}-10^{36}$
yrs. Other decay channels include $Ke$ and $K\mu $ with comparable rates. We
also expect that BR$(\mu \to e\gamma)\sim $BR$(\tau \to \mu \gamma)$.
