Science of Love, Sex, and Babies

Why does your left testicle hang lower?

Posted in news by jenapincott on April 19, 2009

greecesculpturehermes-infant-dionysus While 65 percent of women have a left breast that is larger than the right, the same percentage of men have a left testis that hangs lower in the scrotum than the right. The left testicle also tends to be 7-10 percent smaller.

Why?

It’s a question that won an IgNobel prize for Chris McManus. Although scrotal asymmetry is faithfully reproduced in Greek sculpture, the British psychologist observed, the Greeks weren’t exactly anatomically correct. Greek sculptors faithfully made the left ball lower, but they mistakenly made it larger. Absurdly, they thought the testicles acted like weights to keep open the ducts when semen was released. The left one was erroneously believed to be heavier.

Hundreds of years have passed and we still don’t exactly why the testes aren’t side-by-side and symmetrical, but there are a few theories that touch on the mystery:

Temperature regulation.
A French study found that the left and right testicles have different modes of thermal regulation. The left runs hotter than the right. They hang at different levels because they have separate arteries and veins that differ from each other in length, angle, and source. Sperm are temperature-sensitive, so having redundant semi-independent temperature regulation mechanisms may be beneficial. Researchers also speculate that twin testes, if snugly pressed against each other, would run too hot and thereby impair sperm production. More exposed surface area = cooler. Hanging at slightly different heights prevents them from crushing and overheating each other.

Handedness. Some studies have found that the left testicle hangs lower in right-handed men and the right testicle hangs lower in left-handed men. Handedness is linked to cerebral asymmetry, and there is some suggestion that testicle size and position are, too. Intriguingly, scientists are investigating whether cognitive performance can be predicted by the testes. According to a Canadian study, men with a larger right testicle performed better on spatial tasks than men with a larger left testicle. (Again, on most men, the left is smaller.)

Poor thing. The littler, lighter, lower-hanging left testicle has such a bad reputation that, according to the Urban Dictionary, it’s now slang for slacker.

61 Responses

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  1. Marc said, on April 20, 2009 at 12:05 am

    I always thought that, since testes are very sensitive, one hangs lower than the other so they don’t “bang” into each other while the man walks or runs.

    Why there is a preference for the left might have to do with your two hypotheses.

  2. Ken said, on April 20, 2009 at 11:21 am

    Nice post, but just a word of warning. When I was a teenager (quite a few years ago) I too noticed the asymmetry of my testicles and I too was told this was normal – as you correctly outlined. So I thought nothing more of the size differences in my testicles. But how much asymmetry in size is relative. It ended up my asymmetry in testicle size was not natural – one was cancerous. The degree of asymmetry grew and I should have been more aware. It was not until very late did I finally go see a doctor and found that I had advanced cancer.

    So my word of warning is yes testicle size asymmetry is normal – but if pronounced maybe you want to have things checked out by your physician. Catching cancer early is obviously better than latter.

    Thanks for your interesting post – even if it brings back bad memories🙂

    • guest said, on July 11, 2011 at 2:39 am

      im 14, and my left testicle is larger. it really worries me because not only is it larger but it also has very thick veins. i dont have the guts to tell my dad (cuz its embarrassing). so how do i know if i have cancer? and how do people catch cancer?

      • Brando said, on July 12, 2011 at 6:15 am

        there is nothing embarrassing about it. If what you see you can describe it as “sack of worms”, then maybe you have something called varicocele and you have to check it out. Either tell your father to take you to a doctor or you go straight away.
        Cancer is not contagious. It just happens, could be family related. Anyhow, you have to go and check it at a Urologist or Pediatrician.

  3. […] little piece on testicular asymmetry. Apparently, it’s normal for one ball to be smaller and hang lower […]

  4. Benjamin said, on April 25, 2009 at 4:50 pm

    My right one hangs lower, am I some kind of freak?

    • Benny said, on March 29, 2010 at 6:25 pm

      mine too. im trying to figure that out.

    • karl said, on February 22, 2011 at 7:19 pm

      benjamin are you left handed.

      cos in that artical above it says that men that are left handed usually have the right hanging lower

    • Blake said, on April 25, 2011 at 5:49 pm

      Well, he did say that 65% of men are like this. Maybe you’re part of the other 35%?

  5. Dave said, on April 25, 2009 at 6:00 pm

    Benjamin,

    Is your heart oriented more to the right-hand side of your chest cavity than to the left? In some males other organs may have the same bilateral asymmetry as the testicles. It is an interesting phenomenon and documented to the point that physicians use it as a diagnostic primer. I’ve seen the question asked on university medical school exams.

  6. twpennington said, on April 26, 2009 at 12:05 pm

    One hangs lower so they don’t smash against each other while walking. Otherwise men would be bo-legged just to keep from the pain. But all this goes into the fact that all of us are different on each side of our bodies.
    Try this, take a picture and cover up the left side of the face and then switch sides. You will see to different faces.

  7. danarecom said, on April 26, 2009 at 12:40 pm

    just know bout it… never think bout tat before…

  8. Doc said, on April 26, 2009 at 1:24 pm

    If they hung evenly when they were hit together they would crush each other. Since one is lower, one will override the other if they are mashed together.

  9. Emmanuel said, on April 26, 2009 at 5:50 pm

    I have always thought that they hang lower due to damage. like if they get hit the right one will still work and the left will get hit really hard but won’t work. (you’ll have one working ball rather than none.)

  10. Christopher di Spirito said, on April 26, 2009 at 5:53 pm

    I always figured it was so my package could fit comfortably down the leg of my 501 jeans.

  11. againseminoma said, on April 26, 2009 at 5:54 pm

    lol now i only have one testicle that hangs lowest!

  12. m said, on April 26, 2009 at 6:06 pm

    Are you going to do a post on why the Vagina is shaped like a wallet?

  13. Bruno said, on April 26, 2009 at 6:10 pm

    Now that’s a life-changing information, uh!

  14. Richard Bolai said, on April 26, 2009 at 6:14 pm

    Just think of it, if they were the same identical size and weight, one testis would crush the other, or if they hung too low, they my simply twist together. No Nobel prize for that, just common sense.

  15. umstrum said, on April 26, 2009 at 6:15 pm

    aaah, the wonders of the http://www.. now i know why testicles are asymetrical. this is exactly the kind of thing i wanna learn at 3am on a sunday night

    m. @ http://umstrum.wordpress.com

  16. klyftonite said, on April 26, 2009 at 7:01 pm

    lol i never really questioned that ever..!

    • anthony said, on July 26, 2010 at 3:57 am

      thats because ur aisan and ur shit is so small u cant tell lol

  17. Mike said, on April 26, 2009 at 7:29 pm

    Whilst naked, if you sit, primly, with your knees together, you will see one testicle ride up and over the other. If your testicles hung at the same length then there would be a calamitous crush like when two people try to go through the same door at the same.

    • len said, on September 10, 2011 at 6:19 am

      oooooh that made me cringe

  18. Neal Taylor said, on April 27, 2009 at 4:46 am

    My wife assured me that I am a lower-lefty! LOL

  19. Tyler Dockdery said, on April 27, 2009 at 7:10 am

    Luckily, Someone is doing this research. I thought my tax dollars might be being wasted.

    Tyler Dockery
    http://www.dockerydesign.com
    http://twitter.com/tyler_dockery
    —————

  20. Hussein Nasser said, on April 27, 2009 at 9:21 am

    Nice new information.

  21. Joseph Hagal said, on April 27, 2009 at 6:54 pm

    It’s not like they’re immobile, I’m guessing they would still “fall into place” regardless of what length they hang, there’s plenty of room. I’m liking the reproductive reason. It’s a pretty advanced thermostat, after all🙂

  22. urbandaddy said, on April 27, 2009 at 7:24 pm

    I think it’s the handedness theory. In women since more are right handed, their right breast would be more muscular, therefore smaller, since the breast is mostly fat. That dominant side reason should also lie true for testies, since men have dominant legs too.

    Of course I’ll have to check that theory later… as a left-handed athlete.

  23. autonodrom said, on April 27, 2009 at 8:23 pm

    I suspect that, they have to be oriented in some manner or another. And, as your male body develops they crowd each other together and one falls into place below the other, usually the left one. I guess…

  24. Kama sutra said, on April 29, 2009 at 7:43 am

    I Really Love Reading Your Blog. Excellent. Keep up the great work!

  25. pantsaroundankles said, on April 30, 2009 at 1:43 am

    Great post. There are 1,000 guys at home right now.. with their pants around their ankles checking to see which one hangs lower.

  26. jen said, on April 30, 2009 at 2:16 pm

    i have been conducting my own private survey about this for years, just as a amussing way to start a conversation. It surprised me to see this. I had always theoriesd that the way the testes hung was attached to the handedness because in the womb the side develops first is stronger then the second side (i vaugely remember i was taught that is why some people are right or left handed) so that relates to the testes when; if you are right handed you right side will be stronger = tighter so the musels of your right testie will hold that one closer, and your muscles on the left side weaker = droopier it was reversed for left handed people. that was my conclusion of my privete study any one know any thing about ambedexterious people?

  27. Mark said, on April 30, 2009 at 2:26 pm

    But what does it mean when one of them starts to larger than the other two?

  28. Med Student said, on May 1, 2009 at 12:33 am

    From my understanding and education, I have been taught that this is actually a result of vascular differences. The testicular arteries and veins have different origins and drainage points. (Search for testicular vein images) As a result of these variances, the left testicular vein actually drains into a smaller (renal) vein where the right drains into a larger (inferior vena cava) vein. This will cause the pressure in the left vein to be greater as there is more resistance. Greater pressure and more blood cause the testicle to hang lower as a result. The scrotum also has the ability to contract/relax for temperature regulation which equally plays an important role in this height difference. As for a third reason, the shape of two spheres can be in closest proximity when they are offset just a little allowing the testes to occupy less space than if they were side by side. I hope this enlightens someone, and this is a great question that I am glad to finally have an answer to.

  29. threeofem said, on May 1, 2009 at 3:14 am

    I dunno. With me it’s my third testicle that seems to be the largest.

  30. Auntie Hosebag said, on May 1, 2009 at 1:26 pm

    …and don’t EVEN get me started on ears…

  31. hipmonkey said, on May 1, 2009 at 6:14 pm

    Thanks for the info, it took a lot of balls to write this.

  32. tarius said, on May 4, 2009 at 1:11 am

    nice post, interesting
    now i don’t have to wonder why😀

    trackback on http://uzisero.blogspot.com/

  33. Christopher di Spirito said, on May 4, 2009 at 2:54 pm

    Plus, it’s more aesthetically pleasing.

    The larger ball hangs lower and the slightly smaller ball rests above the bigger one. It forms a graceful, linear line.

    • Rickinatorc said, on June 21, 2010 at 2:59 pm

      If you read the article, it said the lower one is the smaller one.

  34. thatsphuckedup said, on May 6, 2009 at 8:14 am

    Slacker…lol…. I never heard that one

  35. Roger said, on May 7, 2009 at 8:41 am

    It’s all to do with the angle at which the earth spins.

  36. Helioprogenus said, on May 7, 2009 at 9:28 pm

    As far as the speculation goes, what people seem to gloss over is that according to the first part of the article, approximately 35% of men have testicles that are on equal levels. There may be some self reporting bias here, so taking an even more conservative number, we can say that at least 25% have no asymmetry in testicular levels. An interesting study then would be to see if this is related to possible ambidexterity. Also, it would be interesting to see if there’s a correlation with sperm count and testicular dominance. One other thing to keep in mind as far as the speculation, if 25% of the population was the outlier, than they wouldn’t be as likely to reproduce and that trait would not have remained in human populations. Perhaps then, testicular asymmetry isn’t as correlative with dominance as this article maintains. As far as the temperature regulation hypothesis, this must also be tested among the left lower, right lower, and symmetric groups.

    • Rickinator said, on June 21, 2010 at 3:01 pm

      It means 35% of people have the right one hang lower.

  37. gangly said, on May 10, 2009 at 10:15 am

    the good thing about testicular cancer is you can only get it twice.

  38. Burt said, on June 3, 2009 at 7:21 pm

    In my case, the left one does hang lower. But the right one is significantly smaller. All of which means nothing.

    By the way, I am right handed.

  39. nate said, on June 16, 2009 at 3:26 pm

    i am a right-handed man, and my right testicle hangs lower and is smaller. and according to the above text. that is not possible. any comments or concerns?

  40. dick van penershmidt said, on July 7, 2009 at 1:59 am

    how can you tell if one of your testicles is twisted becuase mine sometimes get flipped and stuff when i walk and i think they are back to normal but dont know

  41. Mike Macgirvin said, on December 13, 2009 at 7:00 am

    For a healthy male, it is quite common for the testicles to rise and fall in a complimentary fashion over a period of several seconds, even when symmetrical. So they are only at the same height when passing each other.

    However there are natural causes of one hanging lower *consistently* as have been mentioned. There may be other reasons – mine used to be somewhat symmetrical until a hernia operation a few years back. Now one is consistently lower than the other by a significant amount. This is because the hernia repair altered the muscle tissue in the lower abdomen significantly. It is of no concern as everything seems to function normally.

  42. super leroy said, on May 16, 2010 at 11:07 pm

    Dont you hate it when one of your ball is sweaty and the other two are stuck to the side of your leg?

  43. anat said, on August 5, 2010 at 8:44 am

    There is a scientific and anatomical explanation for it. It is due to the way the blood drains from the testes. The right testis drains directly to the Inferior Vena Cava, whereas the left testis drains into the renal vein at an angle.

    If my memory serves me well, the angle causes blood drainage from the left testis to be less smooth, causing a difference in the blood flow. The difference in blood flow causes the differences in height of the testes.

  44. kirkir said, on August 6, 2010 at 5:19 am

    My left is so smaller that the right one. and i sometimes feel pain. does it mean this normal?

    • krish said, on January 25, 2011 at 11:04 pm

      friend if u hav dull pain or discomfort in one or both testis check it for varicocele with ur urology doctor..

  45. Shakeal Williams said, on November 18, 2010 at 7:12 pm

    hey forget what everybody else is talking about…when i have sex and ejaculate about 2 times my left ball hurts but the right one dosen’t…. why is that? i dont think god made us with one ball bigger than the other one….it’s got to be because of poor blood flow or something like that

  46. Abhishek said, on April 14, 2011 at 6:30 am

    Hey,
    I need help as my right testicle is paining a little bit n its almost a month now and its hanging a bit lower than the left one.
    Can anyone help me?
    (Both are of same size, no mumps or any such thing)

  47. Evin said, on May 8, 2011 at 10:36 pm

    I am 12 i hit puberty and my balls droped what i am trying to wonder is if my left ball that hangs lower and my right that is higher my left ball is small but my right is bigger and im right handed

    • nono said, on July 15, 2011 at 3:19 am

      thats the same with me it just your better on your right side of the body than the left

  48. FMANSJL said, on June 22, 2011 at 4:27 pm

    im right handed and my right is lower, is this bad?

  49. pooper said, on July 13, 2011 at 5:59 am

    hhahahahahaa


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