Why do we feel jealous?

Are we programmed to feel jealous when  something we consider to be our possession goes on to become someone else's possession? I think, yes that is one of the basic human natures and we cannot erase it ever from our psyche. But having said that, each and every individual has a different degree of jealousy, and its never the same.

And also, we can be jealous about both inanimate and animate things alike. A child may be extremely jealous when his favorite  toy  is being given to his best friend, and may react by crying out aloud until his toy his returned to him.
As an adult we could be extremely jealous when someone whom we love starts showing interest in anybody apart from our own selves..

But why...??

It is because somewhere inside, we have given that thing, inanimate or animate, an important place in our lives and cannot  think of parting with it, because we know  it will pain to give away a part of our selves.

But jealousy is not always justified. At times, it could be just an over exaggeration of expression. And this form of jealousy is the outcome of deep insecurities. Insecurity here is the feeling that the thing or person whom we love could be snatched from us anytime.

I too suffer from this feeling many times. And I am still learning to deal with it......