What are armpits for? | Greg Foot | Ask Head Squeeze

This week on #AskHeadSqueeze Thursdays, Greg Foot answers a question from Kevin Sheppard on our Head Squeezers Google+ community. What are armpits for, and why are they hairy? Interested in how the smell of your sweat could help you score? Watch away..... 00:43 Why do we have hairy pits? There's a few theories here. One idea is that your hairy armpits stop your lymph nodes from overheating. Foot Note 1: A moat around castle walls: The role of axillary and facial hair in lymph node protection from mutagenic factors. KomarovaS. Medical Hypotheses, Vol67, Issue 4 (2006), Pg 698-701 http://www.ncbi.nlm.nih.gov/pubmed/16690220 Another is that the hairs actually reduce friction when you walk. But the third theory is the one Greg's keen to talk about -- that hairy armpits are all about sweating and releasing sex pheromones. 01.08: Where does the sweaty smell come from? Before Greg goes Sherlock, he has to explain where your smell comes from. Foot Note 2: Microbiological and biochemical origins of human axillary odour. James AG, Austin CG, Cox DS, Taylor D, Calvert R. FEMS Microbiol Ecol. 2013 Mar;83(3): 527-40. http://www.ncbi.nlm.nih.gov/pubmed/23278215 02:01 What does your sweat say about you? Sometimes your smell can say a whole lot about you, your status, your gender, and your reproductive state - especially if you are a Hyena. Foot Note 3: Animal behaviour meets microbial ecology Archie E, Theis K. Animal Behaviour, Vol 82, Issue 3, 2011, Pg 425--436 http://www.sciencedirect.com/science/article/pii/S0003347211002399 Even in humans, the underarm smell could have a role in attracting a partner. Foot Note 4: MHC-correlated mate choice in humans: a review. Havlicek J, Roberts SC. Psychoneuroendocrinology. 2009 May;34(4):497-512. http://www.sciencedirect.com/science/article/pii/S0306453008002667 03:00 What is the Major Histocompatibility Complex? The MHC is a bunch of genes that are important and are linked to not only your smell but your immune system. Experiments have shown that some women found a man's smell more attractive if his MHC was different from their own. It's thought that this is because their children will have a stronger immune system if they get two different sets of these genes. Foot Note 5: MHC-Dependent Mate Preferences in Humans Wedekind C, Seebeck T, Bettens F, and Paepke A. Proc. R. Soc. Lond. B 22 June 1995 vol. 260 no. 1359 245-249 http://rspb.royalsocietypublishing.org/content/260/1359/245.abstract 04:01 How are steroids linked to your smell? Androstadienone is a by product of testosterone, and researchers have found that women exposed to it at a speed dating event were more likely to rate men as attractive. Footnote 6: Evidence that androstadienone, a putative human chemosignal, modulates women's attributions of men's attractiveness. Saxton T, Lyndon A, Little A, Roberts C. Hormones and behavior 2008; 54(5): 597-601 http://www.ncbi.nlm.nih.gov/pubmed/18601928 04:44 Who has the smelliest armpits? This is the battle of the sexes -- who is smellier, men or women? Well, the research was done by the Monell Chemical Senses Center, and they found...it was men. Sorry guys. And, bonus fact , women apparently prefer the "odor signatures" from men who are on a non-meat diet. Foot Note 7: The effect of meat consumption on body odor attractiveness. Havlicek J, Lenochova P. Chem Senses. 2006 Oct;31(8):747-52. Epub 2006 Aug 4. http://www.ncbi.nlm.nih.gov/pubmed/16891352 Do you smell? James May can't help, but he can tell you how deodorant works. https://www.youtube.com/watch?v=8LabJoi9w4s And if you're still feeling hopped up on animal magnetism, Greg Foot answers more mammalian questions in Can Animals Taste. https://www.youtube.com/watch?v=gqKdNfJzC-g http://www.youtube.com/user/HeadsqueezeTV http://www.youtube.com/subscription_center?add_user=HeadsqueezeTV