Rose, Pete Tyler and others in “The Age of Steel”

[about Lumic] Why's he doing it?

He's dying. This all started out as a way of prolonging life, of keeping the brain alive at any cost.

[to the Doctor] The thing is, I've seen Cybermen before, haven't I? The head. Those handle shapes in Van Statten's museum...

Ah, there are Cybermen in our universe. They started on an ordinary world just like this, then swarmed across the galaxy. This lot are a parallel version, and they're starting from scratch right here on Earth.