 Las Casas has also often been accused of exaggerating the atrocities he described in the Indies, some scholars holding that the initial population figures given by him were too high, which would make the population decline look worse than it actually was, and that epidemics of European disease were the prime cause of the population decline, not violence and exploitation.Demographic studies such as those of colonial Mexico by Sherburne F. Cook in the mid-20th century suggested that the decline in the first years of the conquest was indeed drastic, ranging between 80 and 90%, due of course to many different causes but all ultimately traceable to the arrival of the Europeans.The overwhelming main cause was disease introduced by the Europeans.