The Younger Futhark, also called Scandinavian runes, is a runic alphabet and a reduced form of the Elder Futhark, with only 16 characters, in use from about the 9th century, after a "transitional period" during the 7th and 8th centuries.The reduction, somewhat paradoxically, happened at the same time as phonetic changes that led to a greater number of different phonemes in the spoken language, when Proto-Norse evolved into Old Norse. Also, the writing custom avoided carving the same rune consecutively for the same sound, so the spoken distinction between long and short vowels was lost in writing. Thus, the language included distinct sounds and minimal pairs that were written the same.