Interpersonal loveInterpersonal love refers to love between human beings. It is a much more potent sentiment thana simple liking for another. Unrequited love refers to those feelings of love that are notreciprocated. Interpersonal love is most closely associated with interpersonal relationships.[17]Such love might exist between family members, friends, and couples. There are also a number ofpsychological disorders related to love, such as erotomania.

Pair of Lovers. 14801485

Throughout history, philosophy and religion have done the most speculation on the phenomenonof love. In the 20th century, the science of psychology has written a great deal on the subject. Inrecent years, the sciences of psychology, anthropology, neuroscience, and biology have added tothe understanding of the nature and function of love.

Biological basis

Main article: Biological basis of love

Biological models of sex tend to view love as a mammalian drive, much like hunger or thirst.[19]Helen Fisher, a leading expert in the topic of love, divides the experience of love into three partlyoverlapping stages: lust, attraction, and attachment. Lust is the feeling of sexual desire; romanticattraction determines what partners mates find attractive and pursue, conserving time and energyby choosing; and attachment involves sharing a home, parental duties, mutual defense, and inhumans involves feelings of safety and security.[20] Three distinct neural circuitries, includingneurotransmitters, and three behavioral patterns, are associated with these three romanticstyles.[20]

Lust is the initial passionate sexual desire that promotes mating, and involves the increasedrelease of chemicals such as testosterone and estrogen. These effects rarely last more than a fewweeks or months. Attraction is the more individualized and romantic desire for a specific

candidate for mating, which develops out of lust as commitment to an individual mate forms.Recent studies in neuroscience have indicated that as people fall in love, the brain consistentlyreleases a certain set of chemicals, including the neurotransmitter hormones, dopamine,norepinephrine, and serotonin, the same compounds released by amphetamine, stimulating thebrain's pleasure center and leading to side effects such as increased heart rate, loss of appetiteand sleep, and an intense feeling of excitement. Research has indicated that this stage generallylasts from one and a half to three years.[21]

Since the lust and attraction stages are both considered temporary, a third stage is needed toaccount for long-term relationships. Attachment is the bonding that promotes relationshipslasting for many years and even decades. Attachment is generally based on commitments such asmarriage and children, or on mutual friendship based on things like shared interests. It has beenlinked to higher levels of the chemicals oxytocin and vasopressin to a greater degree than short-term relationships have.[21] Enzo Emanuele and coworkers reported the protein molecule knownas the nerve growth factor (NGF) has high levels when people first fall in love, but these returnto previous levels after one year.[22]