  The eleven-dimensional gravitational action invariant under local Poincare
transformations is given by the dimensional continuation of the Euler class of
ten dimensions. Here we show that the supersymmetric extension of this action
leads, through the Noether procedure, to a theory with the local symmetry group
given by the M-algebra. The fields of the theory are the vielbein, the Lorentz
(spin) connection, one gravitino, and two 1-forms which transform as second and
fifth rank antisymmetric Lorentz tensors. These fields are components of a
single connection for the M-algebra and the supersymmetric Lagrangian can be
seen to be a Chern-Simons form. The dynamics has a multiplicity of degenerate
vacua without propagating degrees of freedom. The theory is shown to admit
solutions of the form S^{10-d} x X_{d+1}, where X_{d+1} is a warped product of
R with a d-dimensional spacetime. Among this class, the gravitational effective
action describes a propagating graviton only if d=4 and the spacetime has
positive cosmological constant. The perturbations around this solution
reproduce linearized General Relativity around four-dimensional de Sitter
spacetime.
