Personally, I feel that human language is the most explicit manifestation of human's unique intelligence and by studying them, we can gain insights into intelligence to build a strong AI.
Although we can think about how we think through metacognition, we cannot really dive into the individual neural activity or anything like that.
Thus, language is the most study-able output of human brain, and I believe that by studying the universals in language across all languages and by exploring the frontiers of human cognition through language construction we can unlock the secrets of human intelligence.
How is human thinking augmented by language?
How is human thinking limited and biased by language?
Can language be more sophisticated or more efficient?
What is the "language" of thought--Mentalese?
As a native speaker of Korean and as a person who is learning Japanese quite seriously (through anime and Memrise), I share a bit about what I have thought about the differences and similarities between Korean and Japanese languages.
Seems like random words meshed up, but well I hope this interests some people.
It is very interesting to watch anime with Korean subtitles, because certain Chinese loanwords in two languages sound almost identical (most of them sound similar) and I can understand about 30% of Japanese perfectly while being always able to identify which Korean words cluster (word + particle grouping) goes with which Japanese speech that was just spoken by an anime character.
It's pretty amazing how much Japanese I can learn from just watching anime. How similar and also different the two languages are interests me a lot.
I am also learning Mandarin Chinese, so I think I'll write about the three major East Asian languages soon.
Good night! Or maybe I should say good morning (it's 2:41 in the morning).