  In classical spin systems with two largely different inherent time scales,
the configuration of the fast spins almost instantaneously follows the
slow-spin dynamics. We develop the emergent effective theory for the slow-spin
degrees of freedom and demonstrate that this generally includes a topological
spin torque. This torque gives rise to anomalous real-time dynamics. It derives
from the holonomic constraints defining the fast-spin configuration space and
is given in terms of a topological charge density which becomes a quantized
homotopy invariant when integrated.
