  The presence of two distant FR I radio galaxies in the Hubble Deep Field plus
Flanking Fields indicates that the number density of these objects is about
10-50 times higher at z>1 than in the local universe. This is in strong
contrast with the idea that FR Is undergo no cosmological evolution. We
advocate that the cosmological evolution of radio sources may be independent of
FR class, and instead solely a function of radio power. In this scenario the
evolutionary properties of extragalactic radio sources can be fully described
within a `single population scheme'.
