I also agree that physical development has to assist the verbal and early talking astounds me. What I did notice with DD is that when she did hit a milestone, she was away to the races.
Ren
I've had the same experience with my kids. DD9 didn't read until she was 4 (almost 5), but then she was reading chapter books within a year. She was talking a lot way before her first birthday, too.
DD6 was much the same as DD9, except she read earlier and walked much earlier (10 months versus 12 for DD9).
DS2 went from crawling to running at 13 months and from barely talking to full sentences at 18 months.
Off to the races is right!
