Geometry is not fundamental. The metric and general relativity can emerge from more basic pregeometry. We formulate a euclidean functional integral for quantum gravity as a Yang-Mills theory with local gauge symmetry SO(4) and diffeomorphism invariance. It shows no instabilities and can be analytically continued to Minkowski signature. The quantum effective action leads to general relativity as an effective low energy theory. This ensures compatibility with the numerous precision tests for gravity. Adding a scalar field the cosmological solutions of the field equations describe an early inflationary epoch and late cosmology with dynamical dark energy and a candidate for dark matter. The beginning is a vacuum state which can be associated to the ultraviolet fixed point of the renormalisation flow. There is no big bang singularity.