  In earlier work the authors have extended Nehari's well-known Schwarzian
derivative criterion for univalence of analytic functions to a univalence
criterion for canonical lifts of harmonic mappings to minimal surfaces. The
present paper develops some quantitative versions of that result in the form of
two-point distortion theorems. Along the way some distortion theorems for
curves in ${\Bbb R}^n$ are given, thereby recasting a recent injectivity
criterion of Chuaqui and Gevirtz in quantitative form.
