My broad conclusion is that an advanced global seafaring civilization existed during the Ice Age, that it mapped the earth as it looked then with stunning accuracy, and that it had solved the problem of longitude, which our own civilization failed to do until the invention of Harrison's marine chronometer in the late eighteenth century. As masters of celestial navigation, as explorers, as geographers, and as cartographers, therefore, this lost civilization of 12,800 years ago was not outstripped by Western science until less than 300 years ago at the peak of the Age of Discovery.