Each of the seven continents had different conditions that created different evolutionary pressures. If Rui had to guess, he would have assumed that Genora had managed to preserve most of the Plant Kingdom, creating evolutionary pressure to form symbiotic relations with trees, such that those who were able to harness their power and preserve them would survive.
This group of humans eventually evolved into the elves, with long ears designed to be receptive to signals from plant-life.
The Moridian Continent must have had rapidly oscillating extremes in environment, allowing only the most physiologically adapting humans of each generation to survive, creating the Darwinian pressure that gave rise to homo evosapien.
