I'd read somewhere that babies don't really start to 'play' with each other until they're around 18 months old.
This morning at mothers group, the baby certainly looked to be playing with another girl! They had a water bottle filled with rice (a toy I would emulate here if I could trust the dogs to not chew it up and get rice everywhere) (I can't) and were taking turns.
Funnily/sadly, the game was that the baby would snatch it over the other girl, and then the other girl would whinge. Then the other girl would reach to take it back, the baby would pass it, and then the baby would whinge and flap her arms like she does when she's cranky. And then she'd snatch it back. And they repeated over and over and over.
It was pretty cute.
It was also pretty interesting that the baby would pass it before the other baby would steal it, but would still give the same reaction.
Empathetic soul that she is.