© 2017. The American Astronomical Society. All rights reserved.We report a long-term study of the eclipse times in the 10 minute helium binary ES Ceti. The binary period increases rapidly, with P/P = 6.2 × 106 years. This is consistent with the assumption that gravitational radiation (GR) drives the mass transfer, and it appears to be the first dynamical evidence that GR is indeed the driver of evolution in this class of very old cataclysmic variables - the AM Canum Venaticorum stars.