Recently, evolutionary psychologist have turned their sights on love and divorce. It didn't take long to notice that when people fall in love, there's period of up to three years during which the zeal and infatuation ride at a peak. The internal signals in the body and breain are literally a love drug. And then it beginds to decline. From this perspective, we are preprogramed to lose interest in a sexual partner after the time required to raise a child has passed - which is, on average, about 4 years. In psychologist Helen Fisher's view, the internally generated love drug love drug is simply an efficient mechanism to get men and women to stick together long enough to increase the survival likehood of their young.