A graph G = (V, E) is globally rigid in R d if for any generic placement p : V → R d of the vertices, the edge lengths p(u) − p(v) , uv ∈ E uniquely determine p, up to congruence. In this paper we consider minimally globally rigid graphs, in which the deletion of an arbitrary edge destroys global rigidity. We prove that if2 . This implies that the minimum degree of G is at most 2d + 1. We also show that the only graph in which the upper bound on the number of edges is attained is the complete graph K d+2 . It follows that every minimally globally rigid graph in R d on at least d + 3 vertices is flexible in R d+1 .As a counterpart to our main result on the sparsity of minimally globally rigid graphs, we show that in two dimensions, dense graphs always contain non-trivial globally rigid subgraphs. More precisely, if some graph G = (V, E) satisfies |E| ≥ 5|V |, then G contains a globally rigid subgraph on at least seven vertices in R 2 . If the well-known "sufficient connectivity conjecture" is true, then this result also extends to higher dimensions.Finally, we discuss a conjectured strengthening of our main result, which states that if a pair of vertices {u, v} is linked in G in R d+1 , then {u, v} is globally linked in G in R d . We prove this conjecture in the d = 1, 2 cases, along with a variety of related results.