Thanks a lot for your answer Wolf Kanno.

In response I would like to elaborate about my theory a little more.

I believe that in that Final Fantasy Universe "Evolution" works in a different way, that the manner we see here in the real world, here evolution works by very gradual mutations and natural selection, this means that from a species to evolve into a different one, it takes thousands of generations, but in the Final Fantasy Universe the process is much more direct and a lot quicker, and that is thanks to "Mako".

I believe that in the Final Fantasy Universe, every life form contains certain amount of Mako, but humans have the ability to control Mako at will, this ability is what is usually known as "Magic", now the more intelligent and wise a person grows, the more powerful and refined their magic becomes, and when they reach certain level of magical power they ascend into a higher tier of "Evolution", this process is deliberate and is much faster that the random accumulative evolution of the real world.

The main difference, between baseline human species, and the ascended species, is that the ascended does not need a physical body to exist and interact with the world, Kluya is dead, yet he helps his son Cecil become a Paladin, Zemus becomes even stronger after is body is destroyed in battle, Aerith keeps helping Cloud after her death, (in both FF7 and Advent Children) I believe this ability to transcend death is a genetic evolution not a technological improvement, that is why I refer to them as a different species, not just the same species with a higher level of technology/culture.

I theorize that a lot of planets developed humans, but that is not by chance, in FF4 The After Years, the final boss of the game, calls himself "The Creator" and tells the heroes that his race deliberately sent "Crystals" to a lot of different planets, with the intention of creating many different human civilizations and study their progress, they did this because they basically destroyed their own planet and their own race, and they want to understand exactly what they did wrong.

This means that every game with "Crystals" is part of the same universe and another part of The Creator's experiment, this would also explain why most of the games have similar aspects, even when they take place in different worlds, I think it is because the "Crystals" are actually super computers made of nanotechnology, and they direct the evolution of life in each planet, all following the same preprogramed patterns, but the expression of these patters varies depending on the local conditions of each planet, that is the reason that most Final Fantasy Worlds had an "Ifrit", but while his basic concept is the same in every game "Magical Beast of Fire " is design and origins are different in each world.