Love

===Biological basis===
{{Main|Biological basis of love}}
Biological models of sex tend to view love as a [[mammal]]ian{{clarify|reason=do other classes of animal not have hunger or thirst?|date=August 2023}} drive, much like hunger or thirst.<ref name="Lewis">{{cite book | last1 = Lewis | first1 = Thomas |last2=Amini|first2= F. |last3=Lannon|first3= R. | title = A General Theory of Love | publisher = Random House | year = 2000 |isbn=978-0-375-70922-7| title-link = A General Theory of Love }}</ref> [[Helen Fisher (anthropologist)|Helen Fisher]], an anthropologist and human behavior researcher, divides the experience of love into three partly overlapping stages: lust, attraction, and attachment. Lust is the feeling of [[sexual desire]]; romantic attraction determines what partners find attractive and pursue, {{clarify|text=conserving time and energy by choosing|reason=it's not clear what this phrase is doing here|date=August 2023}}; and attachment involves sharing a home, parental duties, mutual defense, and in humans involves feelings of safety and security.<ref name="brain systems">
{{cite journal|url=http://homepage.mac.com/helenfisher/archives_of_sex_beh.pdf |title=Defining the Brain Systems of Lust, Romantic Attraction, and Attachment |access-date=3 October 2011 |url-status=dead |archive-url=https://web.archive.org/web/20110628051603/http://homepage.mac.com/helenfisher/archives_of_sex_beh.pdf |archive-date=28 June 2011|journal=Archives of Sexual Behavior|volume=31|number=5|year=2002|first1=Helen E.|last1=Fisher|first2=Arthur|last2=Aron|first3=Debra|last3=Mashek|first4=Haifang|last4=Li|first5=Lucy L.|last5=Brown |pages=413–419 |doi=10.1023/A:1019888024255 |pmid=12238608 |s2cid=14808862 }}</ref> Three distinct neural circuitries,{{Specify|date=August 2023}} including neurotransmitters,{{Specify|date=August 2023}} and three behavioral patterns,{{Specify|date=August 2023}} are associated with{{How|date=August 2023}} these three romantic styles.<ref name="brain systems"/>

[[File:Gothaer Liebespaar.jpg|thumb|left|180px|''Pair of Lovers''. 1480–1485]]
[[Lust]] is the initial passionate sexual desire that promotes [[Mating (human)|mating]], and involves the increased release of [[hormones]] such as [[testosterone]] and [[estrogen]]. These effects rarely last more than a few weeks or months. [[Interpersonal attraction|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 form. Recent studies in [[neuroscience]] have indicated that as people fall in love, the brain consistently releases a certain set of chemicals, including the [[neuroendocrine|neurotransmitter hormones]] [[dopamine]], [[norepinephrine]], and [[serotonin]], the same compounds released by [[amphetamine]], stimulating the brain's [[pleasure center]] and leading to side effects such as increased [[heart rate]], [[Anorexia (symptom)|reduced appetite]] and [[insomnia|sleep]], and an [[euphoria|intense feeling of excitement]]. Research indicates that this stage generally lasts from one and a half to three years.<ref name="human">{{cite book | publisher=Holt, Rinehart, & Winston | title=Holt World History: The Human Legacy | date=2008-01-01 | isbn=978-0-03-093780-4 }}</ref>

Since the lust and attraction stages are both considered temporary, a third stage is needed to account for long-term relationships. [[Attachment theory|Attachment]] is the [[human bonding|bonding]] that promotes relationships lasting for many years and even decades. Attachment is generally based on commitments such as marriage and children, or mutual friendship based on things like shared interests. It has been linked to higher levels of the chemicals [[oxytocin]] and [[vasopressin]], to a greater degree than what is found in short-term relationships.<ref name="human"/> [[Enzo Emanuele]] and coworkers reported the protein molecule known as the [[nerve growth factor]] (NGF) has high levels when people first fall in love, but these return to previous levels after one year.<ref>{{cite journal|last1=Emanuele|first1= E.|last2=Polliti|first2= P.|last3=Bianchi|first3= M.|last4=Minoretti|first4= P.|last5=Bertona|first5= M.|last6=Geroldi|first6= D.|year=2005|title=Raised plasma nerve growth factor levels associated with early-stage romantic love|url=https://www.sciencedirect.com/science/article/abs/pii/S0306453005001976|journal=Psychoneuroendocrinology|doi=10.1016/j.psyneuen.2005.09.002|volume=31|pmid=16289361|issue=3|pages=288–294|s2cid=18497668|access-date=3 December 2006|archive-url=https://web.archive.org/web/20061206142641/http://www.biopsychiatry.com/lovengf.htm|archive-date=6 December 2006|url-status=live}}</ref>
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