Morphine, like many prescription drugs, may require larger doses for pain control when used for extended periods of time. Over time, the body can develop a tolerance for the medication and will require more medication to experience the same level of effectiveness.
By Kimberly Munro Fri, Mar 18, 2011. The first installment of our Ancient Peru series relates what archaeology has revealed about its first cities and civilizations. The expansive, culturally rich civilizations that existed in the Americas at the time of European contact came as a great surprise to the early Spanish explorers. Most notable were the Aztec empire in Central Mexico and the Incan empire in Peru, both of which controlled great expanses of land and millions of people.
In short, the Maya came first, and settled in modern-day Mexico. Next came the Olmecs, who also settled Mexico. They didnât build any major cities, but they were widespread and prosperous. They were followed by the Inca in modern-day Peru, and finally the Aztecs, also in modern-day Mexico.he Maya were the first Mesoamerican civilization, starting around 2600 B.C. They lasted the longest of all and are often viewed as the greatest Mesoamerican civilization. They built most of their great cities between A.D. 250 and A.D. 900.