Body odor
Body odor is present both in animals and humans and its intensity can be influenced by many factors (behavioral patterns, survival strategies). Body odor has a strong genetic basis both in animals and humans, but it can be also strongly influenced by various diseases and psychological conditions.
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[edit] Causes
Not only sweat glands but also sebaceous glands and apocrine sweat glands produce substances contributing to body odor. Sebaceous and apocrine become active at puberty. This as well as many apocrine glands being close to the sex organs points to a role related to mating. In humans the armpit regions seem more important than the genital region for body odor which may be related to human bipedalism. The genital and armpit regions also contain springy hairs which help diffuse body odors.[1]
Factors such as food, drink, and diseases can affect body odor.[1] An individual's body odor is also influenced by lifestyle, gender, genetics, and medication.
Body odor is influenced by the actions of the skin flora, including members of Corynebacterium, which manufacture enzymes called lipases that break down the lipids in sweat to create smaller molecules like butyric acid. These smaller molecules smell, and give body odor its characteristic aroma.[2] Propionic acid (propanoic acid) is present in many sweat samples. This acid is a breakdown product of some amino acids by propionibacteria, which thrive in the ducts of adolescent and adult sebaceous glands. Because propionic acid is chemically similar to acetic acid with similar characteristics including odor, body odors may be identified as having a vinegar-like smell by certain people.[citation needed] Isovaleric acid (3-methyl butanoic acid) is the other source of body odor as a result of actions of the bacteria Staphylococcus epidermidis,[3] which is also present in several strong cheese types.
[edit] In animals
Body odor is an important feature of animal morphology. It plays different role in different animal species. For example, in some predator species, who use stalking as a means of hunt (for example big and small cats), the absence of body odor is highly important, and they spend plenty of time and energy to keep their body free of odor. For other predators, who use long running after the prey as a means of hunting (dogs, wolves), the absence of body odor is not so important, on the contrary, can play a role of warning signal. In most of the animals body odor intensifies in the moment of stress and danger.
[edit] Evolutionary function
Although today body odor is mostly viewed as something negative, in many animals body odor played and still plays an important survival function. Strong body odor can be a warning signal to would be predators to stay away, or it can be also a signal that the prey animal is unpalatable. For example, some animals species, who feign death to survive (like possums), in this state produce a strong body odor to deceive a predator that the prey animal has been dead for a long time and is already in the advanced stage of decomposing. Some animals with strong body odor are rarely attacked by most of the predators, although they can be still killed and eaten by the birds of prey, who have very poor sense of smell.
[edit] Evolutionary function of human body odor
It has been suggested that human body odor played a role of aposematic olfactory warning display signal in early hominids, particularly at night, when hominids were sleeping in the open savannah[4]. As many predators approach their prey against the wind, the strong body odor would inform predators about the identity and the size of the hominid group. Joseph Jordania explained the presence of patches of hair in human armpits and genitals by the evolutionary need to produce stronger body odor. According to his suggestion, body odor lost its survival value after humans developed more advanced means of safety (controlled fire, shelters, effective weapons), and therefore started disappearing, gradually becoming an unwanted legacy of our evolutionary past.
[edit] Specificity
Body odor can smell pleasant and specific to the individual and can be used to identify people, though this is more often done by dogs and other animals than by humans.
Babies can recognize their mothers by smell and mothers and other relatives can identify a baby by smell.[1]
[edit] Genetics
Body odor is largely influenced by major histocompatibility complex (MHC) molecules. These are genetically determined and play an important role in immunity of the organism. The vomeronasal organ contains cells sensitive to MHC molecules in a genotype-specific way.
Experiments on animals and volunteers have shown that potential sexual partners tend to be perceived more attractive if their MHC composition is substantially different. Married couples are more different regarding MHC genes than would be expected by chance. This behavior pattern promotes variability of the immune system of individuals in the population, thus making the population more robust against new diseases. Another reason may be to prevent inbreeding.[1]
One study suggests that body odor is genetically determined by a gene that also codes the type of earwax one has.[5][6] East Asians (those of Chinese, Japanese, Korean, and Vietnamese descent) have the type of sweat glands that even after hitting puberty still don't produce the chemicals found in the perspiration of other ancestral groups. East Asians evidently have a greater chance of having the 'dry' earwax type and reduced axial sweating and odor. This may be due to adaptation to colder climates.
[edit] Alterations
Body odor may be reduced or prevented or even aggravated by using deodorants, antiperspirants, disinfectants , underarm liners, triclosan), special soaps or foams with antiseptic plant extracts such as ribwort and liquorice, chlorophyllin ointments and sprays topically, and chlorophyllin supplements internally.[7] Although body odor is commonly associated with hygiene practices, its presentation can be affected by changes in diet as well as the other factors discussed above.[8]
[edit] Bad smell
| Body odor | |
|---|---|
| Classification and external resources | |
| ICD-10 | L75.0 |
| ICD-9 | 705.89 |
| DiseasesDB | 28886 |
| eMedicine | derm/597 |
The condition can be known medically as bromhidrosis, apocrine bromhidrosis, osmidrosis, ozochrotia, fetid sweat, body smell or malodorous sweating.[9]:779[10]:707
[edit] See also
[edit] References
- Notes
- ^ a b c d The Oxford Handbook of Evolutionary Psychology, Edited by Robin Dunbar and Louise Barret, Oxford University Press, 2007, Chapter 22 Body odours and body odour preferences in humans by Claus Wedekind
- ^ Buckman, Dr. Robert (2003). Human Wildlife: The Life That Lives On Us. Baltimore: The Johns Hopkins University Press. pp. 93-4
- ^ Ara K, Hama M, Akiba S et al (2006). "Foot odor due to microbial metabolism and its control". Can. J. Microbiol. 52 (4): 357–64. doi:10.1139/w05-130. PMID 16699586.
- ^ Joseph Jordania. Why do People Sing? Music in Human Evolution. Logos, 2011:123-124
- ^ Wade, Nicholas (2006-01-29). "Japanese Scientists Identify Ear Wax Gene". New York Times. http://www.nytimes.com/2006/01/29/science/29cnd-ear.html?ex=1296190800&en=7f6c667589328421&ei=5088&partner=rssnyt&emc=rss. Retrieved 2007-07-05.
- ^ Yoshiura K, Kinoshita A, Ishida T et al (2006). "A SNP in the ABCC11 gene is the determinant of human earwax type". Nat. Genet. 38 (3): 324–30. doi:10.1038/ng1733. PMID 16444273. http://www.nature.com/ng/journal/v38/n3/abs/ng1733.html.
- ^ "Chlorophyll and Chlorophyllin". http://lpi.oregonstate.edu/infocenter/phytochemicals/chlorophylls/. Retrieved 2010-01-29.
- ^ "Learn How to Fight Body Odor". http://www.mdhealthnetwork.org/BodyOder.html. Retrieved 2007-07-05.
- ^ James, William; Berger, Timothy; Elston, Dirk (2005). Andrews' Diseases of the Skin: Clinical Dermatology. (10th ed.). Saunders. ISBN 0721629210.
- ^ Freedberg, et al. (2003). Fitzpatrick's Dermatology in General Medicine. (6th ed.). McGraw-Hill. ISBN 0071380760.
[edit] External links
- Flores G (2004). "Immunity, smell linked". The Scientist 5 (1). http://www.the-scientist.com/news/20041105/02.
- Male sweat boosts women's hormone levels -- from UC Berkeley, February 2007
- "Odors and metabolic disease" from Miami Children's Brain Institute
- Causes of body odor
- What is body odour? - Medical article, December 2009.
