Editing Body odor (section)

==== Sexual selection ====
Pheromones are a factor seen in the mating selection and reproduction in humans. In women, the sense of olfaction is strongest around the time of [[ovulation]], significantly stronger than during other phases of the [[menstrual cycle]] and also stronger than the sense in males.<ref>{{harvnb|Lundström|Olsson|2010|ps=:"In addition, the impact that biological factors have on our percept of body odors has recently been indirectly demonstrated by several experiments. Our percept of body odors is dependent on the sexual orientations of both the donor and the perceiver (Martins et al., 2005), and heterosexual women's percept of men's body odor varies over their menstrual cycle (Roberts et al., 2004)."}}</ref><ref>{{cite journal | vauthors = Navarrete-Palacios E, Hudson R, Reyes-Guerrero G, Guevara-Guzmán R | title = Lower olfactory threshold during the ovulatory phase of the menstrual cycle | journal = Biological Psychology | volume = 63 | issue = 3 | pages = 269–279 | date = July 2003 | pmid = 12853171 | doi = 10.1016/s0301-0511(03)00076-0 | s2cid = 46065468 | doi-access = free }}</ref> Pheromones can be used to deliver information about the [[major histocompatibility complex]] (MHC).<ref name="Grammer_2005"/>   The MHC in humans is referred to as the [[Human leukocyte antigen|Human Leukocyte Antigen]] (HLA).<ref name="Kromer_2016">{{cite journal | vauthors = Kromer J, Hummel T, Pietrowski D, Giani AS, Sauter J, Ehninger G, Schmidt AH, Croy I | title = Influence of HLA on human partnership and sexual satisfaction | journal = Scientific Reports | volume = 6 | pages = 32550 | date = August 2016 | pmid = 27578547 | pmc = 5006172 | doi = 10.1038/srep32550 | bibcode = 2016NatSR...632550K }}</ref> Each type has a unique scent profile that can be utilized during the mating selection process. When selecting mates, women tend to be attracted to those that have different HLA-types than their own.<ref name="Grammer_2005" /><ref name="Kromer_2016" />  This is thought to increase the strength of the family unit and increase the chances of survival for potential offspring.<ref name="Grammer_2005" />

Studies have suggested that people might be using odor cues associated with the immune system to select mates. Using a brain-imaging technique, Swedish researchers have shown that [[homosexuality|homosexual]] and [[heterosexuality|heterosexual]] males' brains respond in different ways to two odors that may be involved in sexual arousal, and that homosexual men respond in the same way as heterosexual women, though it could not be determined whether this was cause or effect. When the study was expanded to include lesbian women, the results were consistent with previous findings – meaning that lesbian women were not as responsive to male-identified odors, while responding to female odors in a similar way as heterosexual males.<ref>{{cite journal |vauthors=Berglund H, Lindström P, Savic I |date=May 2006 |title=Brain response to putative pheromones in lesbian women |journal=Proceedings of the National Academy of Sciences of the United States of America |volume=103 |issue=21 |pages=8269–8274 |bibcode=2006PNAS..103.8269B |doi=10.1073/pnas.0600331103 |pmc=1570103 |pmid=16705035 |doi-access=free}}</ref> According to the researchers, this research suggests a possible role for human pheromones in the biological basis of [[sexual orientation]].<ref>{{cite news |date=9 May 2005 |title=Gay Men Are Found to Have Different Scent of Attraction |work=The New York Times |url=https://www.nytimes.com/2005/05/09/science/09cnd-smell.html |vauthors=Wade N}}</ref>