Human population 50-40 thousand years ago was about 1.5 million as calculated by paleodemographer Jean-Noel Biraben, according to a report in Science et Avenir March 2012 page 58. In Europe the population of hunter-gatherers was 200,000 just before the demographic transition of the neolithic 9000 ybp. This figure represents 0.05 people per square kilometer according to calculations by Jean-Pierre Bocquet-Appel, director of research at the French National Center for Scientific Research (CNRS).