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.
The Origins of the Aztecs. The Aztecs, or Mexica as they called themselves, were not originally from the Valley of Mexico, but rather migrated from the north, from a mythical island called Aztlan, The Place of Herons..enochtitlan is an archaeological ruin located under the streets of modern Mexico City in the Valley of Mexico. According to historical documents, the Aztecs wandered for years in search of a new homeland before locating the capital city for their empire at TenochtitlaÂ¡tenochtitlÃ£ n in. 1325