6、Language is always changing. In a society where life continues year after year with few changes，the languages do not change either. The earliest known languages had difficult grammar but a small，limited vocabulary. Over the century，the grammar changed，and the vocabulary grew. For example，the English and Spanish people who came to America during the sixteenth century gave names to all the new plants and animals they found. In this way，hundreds of new words were introduced into English and Spanish vocabularies. Today life is changing very fast，and language is changing fast too.
There are several major (主要的) language families in the world. Some scientists say there are nine main families，but other scientists divided them differently. The languages in each family are connected，and scientists think that they came from the same parent language. About 3% of the people in the world speak languages that are not in these major families.