system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How do we know that languages like Sanskrit and most the European languages are descended from the same language but languages like Basque we know are completely unrelated to any known language?
gpt
We can compare the words for different things in different languages. If the words are almost the same then it is likely that the languages are very closely related. For example Spanish and Portuguese share a lot of words and grammar. The less similar they are the longer back they separated. For example Spanish and French both share some words and most words have the same base but are pronounced and spelled differently. When you get really far back it can be hard to see how they are related but you can track some words back to their origins. For example French and German sounds very differently but if you compare each word you can find similarities. Where possible you can also go back in ancient texts and find the original common language between them. For example French and Hindu have very little in common but there are texts from the bronze age which show similarities with both of the languages. And then you have languages like Basque, Mandarin and Finish which do not have anything in common with most other languages even how hard we try to find a link.