I have already taken a Y-chromosome DNA (Y-DNA) STR test. Why do I need to take a SNP test? What more can it show me?

Ordering a Y-chromosome DNA (Y-DNA) SNP test will tell you more about your deeper ancestry. That is, the historic migrations of your direct paternal ancestors. This extends what you have learned about your ancestry from one of our Y-DNA STR tests. It enhances it.