person = Person.find_by_name('uncle bob')
person.changed?       # => false

person.name = 'Bob'
person.changed?       # => true
person.name_changed?  # => true
person.name_was       # => 'uncle bob'
person.name_change    # => ['uncle bob', 'Bob']
person.name = 'Bill'
person.name_change    # => ['uncle bob', 'Bill']