Does marriage make you smarter?
I can't speak to marriage from personal experience, not having done it yet. However, from a practical perspective, having an intelligent and supportive partner has the practical effect of seeming smarter. You can constantly hone ideas by discussing them, and you can make sure one another does the things you're supposed to do. You can comment on one another's work and hone arguments.
What success I've had in the last 12 years has been significantly enhanced by my significant other, and I know more and am better at various things because of her.