  Using redshift space distortion data, we perform model-independent
reconstructions of the growth history of matter inhomogeneity in the expanding
Universe using two methods: crossing statistics and Gaussian processes. We then
reconstruct the corresponding history of the Universe background expansion and
fit it to type Ia supernovae data, putting constraints on
$(\Omega_\mathrm{m,0},\sigma_{8,0})$. The results obtained are consistent with
the concordance flat-$\Lambda$CDM model and General Relativity as the gravity
theory given the current quality of the inhomogeneity growth data.
