Dynamically mixin a base class to an instance in Python

Is it possible to add a base class to an object instance (not a class!) at runtime? Something along the lines of how Object#extend works in Ruby:

class Gentleman(object):
  def introduce_self(self):
    return "Hello, my name is %s" % self.name

class Person(object):
  def __init__(self, name):
    self.name = name

p = Person("John")
# how to implement this method?
extend(p, Gentleman)
p.introduce_self() # => "Hello, my name is John"