This is Bearhead.

For some reason or another, he woke up like this one day, only to find that no one he knows remembers him at all. His parents, best friend, classmates, people at his job, etc. Course, it's even scarier when everyone is completely FINE with a man with a bear head that can speak... But, though he's completely intact with all his memories of his loved ones, he's gotta figure out what caused all this and hopefully come to reverse it so he can go back to his old life again.

He slowly develops the attributes/characteristics of a bear... slooowly.