So a funny thing happened around the time the baby turned 6 months old - he somehow transformed into a real person, instead of the adorable but decidedly proto-human he had been.
I think a lot this has to do with his mastery of sitting. About a week before his 6-month birthday, he started balancing himself in an unsupported sitting position. Previously he would list to and fro before flopping over to one side. Now he could keep himself seated, and this opened up a whole new world - he could reach a variety of toys arrayed in front of him, see a room instead of just the ceiling, observe the street from his stroller, and sit up in a high-chair during dinner just like an actual member of the family.
The Pit started taking him down to the carpeted basement for playtime, and we figured out that he knew how to play a version of catch. It's more roll than throwing, but he totally understands the conventions - when handed his ball he flings it in our general direction, grins, and then patiently waits for it to be returned to his grasp via rolling or light bouncing. Then the cycle repeats.
He also impressed me the other day by decoding the operation of one of his musical toys - this thing is a triangle of plastic, and when hit or shaken, it plays several seconds of music. I keep it by his diaper changing station, and used to shake it and then hand to him. He would fling it about, more or less accidently activating the musical function and always looking both surprised and delighted when it played. Now I don't need to activate it first - when I give it to him, he clenches it tightly in one hand, and then slaps it with the other. The music plays, he listens, and then when the music stops he slaps the toy again.
The impressive part is that he started generalizing this to other toys - now when handed an object, the first thing he does is test its musical potential by slapping it in exactly the same way. Since many of his toys have some sort of rattle or music built in, his new-found technique brings him much satisfaction.
Unfortunately, another thing that is currently bringing Fuzzy satisfaction is flinging said toys off of his high chair and then screaming until they are returned to him....I guess as parents, we win some and then we lose some.
5 years ago