In 1986 Henry Lieberman presented at OOPSLA a really simple object system based on delegation to any other object rather than on inheritance through some fixed tree of definitions.
As long as we still care about objects then, here comes Ian Piumarta with his new one(s), er, two, no, one: "Pepsi" and "Coke". In a recent addition to Pepsi, Ian has delicately spliced the two worlds together...
Compared to inheritance, delegation is the more flexible and general of the two techniques. However, they both have their place within an object model: inheritance for sharing of implementation state (and the methods that act upon it) for a single prototype (within a hierarchy of related prototype families), and delegation for sideways composition of (independent and previously unrelated) prototypes into a single logical composite object. This is the position adopted (and implemented) for sideways composition of Pepsi objects.