After the Fall of Rome, the Catholic Church became the sole preserver of literate scholarship in Western Europe. The church established cathedral schools in the Early Middle Ages as centers of advanced education. Some of these establishments ultimately evolved into medieval universities and forebears of many of Europe's modern universities. During the High Middle Ages, Chartres Cathedral operated the famous and influential Chartres Cathedral School. The medieval universities of Western Christendom were well-integrated across all of Western Europe, encouraged freedom of inquiry, and produced a great variety of fine scholars and natural philosophers, including Thomas Aquinas of the University of Naples, Robert Grosseteste of the University of Oxford, an early expositor of a systematic method of scientific experimentation, and Saint Albert the Great, a pioneer of biological field research. Founded in 1088, the University of Bologne is considered the first, and the oldest continually operating university.
Try to answer this question if possible (otherwise reply "unanswerable"):  What did these early schools during the Middle Ages evolve from?
unanswerable