God bless Nana.
First it was "Hi!". Zoe started saying that with Nana's encouragement.
Then it was waving. Or, actually, opening and closing her hands in response.
Now it's crawling. Zoe got excited by the cat and Huck's disgusting, saliva drenched toy and decided, "I need that!". And off she went. It all started, literally, ten minutes before this video. So, here we are, our world has officially changed.