Now these are what I call milestones;
She's sitting up on her own without any support. I've been taking her outside on nice days to let her sit on her blanket taking in nature. She needs help to sit up but once she's squarely on her butt, she's able to sit up.
She's also got her first tooth. A lower incisor. Coolness!
My wife is absolutely, 100% certain that when she says "da da", she means me as in her father. I'm certain that it's just her babbling and exercising her mouth and vocal cords. My wife keeps getting her to day "ma ma" because she's jealous that Olivia can say "da da".