system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How come black people have predominately curly hair?

And how come some other races don't?  I've never seen an Asian with curly hair for example.
gpt
For the first humans living in Africa, the curly hair offered distinct evolutionary advantages such as:

- protecting the head from UV radiation (the head being the most important part of the body and therefore needing protection the most),
- not becoming a soggy clump covering your eyes when wet, and
- allowing increased airflow around the head 

For those who migrated to other parts of the world, these benefits didn't necessarily apply.