A global next-to-leading order QCD analysis of unpolarized and polarized deep-inelastic scattering data is performed with parton distributions constructed in a statistical physical picture of the nucleon. The chiral properties of QCD lead to strong relations between quarks and antiquarks distributions and the importance of the Pauli exclusion principle is also emphasized. We obtain a good description, in a broad range of x and Q², of all measured structure functions in terms of very few free parameters. Forthcoming experiments at RHIC--BNL are sensitive tests of the statistical model for the behavior of the \bar d(x) / \bar u(x) ratio for x \geq 0.2 and for the magnitude and sign of \Delta \bar u(x) and \Delta \bar d(x).

PACS numbers: 13.60.--r, 13.60.Hb, 13.88.+e, 14.20.Dh