  The current understanding of the spin evolution of young pulsars is reviewed
through a compilation of braking index measurements. An immediate conclusion is
that the spin evolution of all pulsars with a measured braking index is not
purely caused by a constant magnetic dipole. The case of PSR J1734-3333 and its
upward movement towards the magnetars is used as a guide to try to understand
why pulsars evolve with n < 3. Evolution between different pulsar families,
driven by the emergence of a hidden internal magnetic field, appears as one
possible picture.
