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.
Sites containing traces of the Olmec civilization are found mainly on the southern coast of the Gulf of Mexico, specifically in the states of Veracruz and Tabasco. Although the Olmecs did have a system of writing, only few of their inscriptions are available to archaeologists at present.exico is perhaps most well-known, archaeologically speaking, as the home of the Aztec civilization. Yet, before the arrival of the Aztecs, another sophisticated civilization, the Olmecs, ruled the region for almost 1000 years.