If we conjugate the verb of the 1st group in french, we will find, there is the -E ending in 1st point singular. (Je parlE, je trouvE).
So how did this -E appear? I know that during the period of Vulgar Latin in the French language the Latin sound -O, which used to be on this place, was reduced (so the verb sounded like "Je parl"). But what happened after it, making the ending -E appear?
By the way, the latin sound -O, which was reduced in french, is still alive in other roman languages (io amo (it))