"We propose a multidisciplinary approach involving mineral physics, geophysics and geodynamics to study the evolution and the current physical conditions of the Earth’s mantle. Starting from a mineral physics database, we will jointly invert long-period seismic waveforms and gravity data to infer 3-D thermal and compositional structure of the Earth’s mantle. The thermodynamic database used for the inversion will also provide the physical properties for time-dependent mantle convection computations. The reconstruction of the thermal and compositional evolution with most advanced computational techniques will validate the character of the T-C structures obtained from the observations. Moreover, these models will give insights on small-scale heterogeneities that are not resolved from the geophysical observations. The proposed combined procedure has a greater potential for answering questions compared to conventional methods, which use only partial information. We expect to shed a light, for example, on the role and presence of water in the deep interiors, on the scale of mantle heterogeneities and on the presence of compositional stratification in the upper and deep mantle. All the specific results are included within the more general goal of achieving a better understanding of the Earth and planetary dynamics. As a consequence, external phenomena as climate change, volcanic eruptions, earthquakes and plate tectonics, that are intrinsically linked to interior dynamics, will be also better understood."