We report a comparative study of the dynamics of Cu₂O, Ag₂O, and Au₂O (i.e., M₂O with M=Au, Ag, and Cu) using first principle calculations based on the density functional theory. Here, for the first time, we show that the nature of chemical bonding and open space in the unit cell are directly related to the magnitude of thermal expansion coefficient. A good match between the calculated phonon density of states and that derived from inelastic neutron scattering measurements is obtained for Cu₂O and Ag₂O. The calculated thermal expansions of Ag₂O and Cu₂O are negative, in agreement with available experimental data, while it is found to be positive for Au₂O. We identify the low energy phonon modes responsible for this anomalous thermal expansion. We further calculate the charge density in the three compounds and find that the magnitude of the ionic character of the Ag₂O, Cu₂O, and Au₂O crystals is in decreasing order, with an Au-O bond of covalent nature strongly rigidifying the Au₄O tetrahedral units. The nature of the chemical bonding is also found to be an important ingredient to understand the large shift of the phonon frequencies of these solids with pressure and temperature. In particular, the quartic component of the anharmonic term in the crystal potential is able to account for the temperature dependence of the phonon modes.