This is often referred to as FIFO, a method of processing and retrieving inventory which connotes that the oldest inventory items are recorded as sold first. In reality, it is not necessarily mean that the exact oldest physical object has been tracked and sold. A times, customers dictate what goes out first by their preference for the best and newest.
The import of the above is to liken this phenomenon to human beings who come and go in the procession of their evolution into this planet. But most of the times, last-in goes first. This is misery!
