Scientists have found out, at which point there was a feeling of love.
The feeling, which later transformed into love, emerged at the moment when the primates, the males helped the females protect offspring from external aggression, for example, coming from other males. To such conclusion researchers have come, having studied the behavior of monkeys and dolphins - the animals closest to man in intelligence.
In the process of evolution the sense has changed considerably and today it is the main modern love.
By the way, managed to establish that at the time of love the person is active the same brain, which is responsible for the parental instinct.