  We have reconstructed the three-dimensional density fluctuation maps to z ~
1.5 using the distribution of galaxies observed in the VVDS-Deep survey. We use
this overdensity field to measure the evolution of the probability distribution
function and its lower-order moments over the redshift interval 0.7<z<1.5. We
apply a self-consistent reconstruction scheme which includes a complete
non-linear description of galaxy biasing and which has been throughly tested on
realistic mock samples. We find that the variance and skewness of the galaxy
distribution evolve over this redshift interval in a way that is remarkably
consistent with predictions of first- and second-order perturbation theory.
This finding confirms the standard gravitational instability paradigm over
nearly 9 Gyrs of cosmic time and demonstrates the importance of accounting for
the non-linear component of galaxy biasing to consistently reproduce the
higher-order moments of the galaxy distribution and their evolution.
