  The Turing instability paradigm is revisited in the context of a multispecies
diffusion scheme derived from a self-consistent microscopic formulation. The
analysis is developed with reference to the case of two species. These latter
share the same spatial reservoir and experience a degree of mutual interference
due to the competition for the available resources. Turing instability can set
in for all ratios of the main diffusivities, also when the (isolated) activator
diffuses faster then the (isolated) inhibitor. This conclusion, at odd with the
conventional vision, is here exemplified for the Brusselator model and
ultimately stems from having assumed a generalized model of multispecies
diffusion, fully anchored to first principles, which also holds under crowded
conditions.
