Simplify the following text for a Grade 11 native English-speaking person.
Original: Notably , the laryngeal theory , in its early forms discussed since the 1880s , became mainstream after Jerzy KuryÅ owicz 's 1927 discovery of the survival of at least some of these hypothetical phonemes in Anatolian .
Simplified: The idea that there was such a language was supported by the fact , that in 1927 Jerzy KuryÅ owicz discovered some of the phonemes , one supposed to be Proto-Indo-European in Anatolian .