How could humans have interbred with Neanderthals if we're a different species?

We are almost the same as Neanderthals, just like two cousins who look similar but have small differences.

Imagine you and your cousin both love to play with blocks. You’re both happy building towers, but sometimes you each use slightly different colored blocks or stack them in a little different way. Even though you're not exactly the same, it's easy for you to share toys, and even have babies together!

Neanderthals were like our cousins who lived nearby. We had similar features, both of us had big brains and could walk on two legs. But we weren’t exactly the same, just like you and your cousin aren't exactly the same.

Even though we were a little different, it was easy for humans and Neanderthals to talk, play, and even have babies together, kind of like when you and your cousin both want to build the tallest block tower! That’s how we could interbreed, even if we’re not exactly the same. We are almost the same as Neanderthals, just like two cousins who look similar but have small differences.

Imagine you and your cousin both love to play with blocks. You’re both happy building towers, but sometimes you each use slightly different colored blocks or stack them in a little different way. Even though you're not exactly the same, it's easy for you to share toys, and even have babies together!