I will relate one of the saddest stories I have ever witnessed. It’s purpose is not to prove anything, other than be anecdotal evidence that if girls are taught how to learn then they will be able to learn similarly to boys.
I once saw a Chassidish man chatting up a very modern girl for an extended period of time. Afterwards, I asked him what happened. I assumed that she was a cousin or something. He said he asked her something because he needed assistance with something and then they ended up talking in learning for 20 minutes. I asked him if he thought it was okay to talk in learning with a girl. He said absolutely not. I asked him why he did it. He said that he couldn’t stop thinking of his mother. When I asked him to elaborate, he said, “If my mother knew how to talk in learning like this girl did then I might actually have something to talk to her about.”
Now, there are a lot of things that can be drawn from this story, the first and foremost being that this guy’s family has some issues and nothing more than that. But I think it does show that girls can at least learn in similar fashion to boys if given the same upbringing. (I am not commenting on whether or not it is Muttar for girls to learn and such; this is only about physical and intellectual capabilities.)