  The parametrized Duffin-Kemmer-Petiau wave equation is formulated here for
many relativistic particles of spin-0 or spin-1. The conventional
second-quantized or Fock-space proof of the spin-statistics connection requires
that the fields of creation and annihilation operators satisfy commutation
relations subject to causality conditions. The conditions restrict entanglement
to spacelike separations of the order of the Compton wavelength $\hbar/mc$.
Relativistic quantum mechanics is used here to prove the symmetry of the
wavefunctions for identical particles, following the nonrelativistic argument
of Jabs (Found. Phys. 2010, v40, 776--792). First quantization does not require
causal commutation relations, and so entanglement is unrestricted.
