# Are all homo sapiens of the same handedness? **URL:** \ **Category:** Factual Questions\ **Created:** [February 9, 2004, 1:24pm UTC](https://boards.straightdope.com/t/are-all-homo-sapiens-of-the-same-handedness/228262 "2004-02-09T13:24:19Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![spingears](https://avatars.discourse-cdn.com/v4/letter/s/ebca7d/32.png) [@spingears](https://boards.straightdope.com/u/spingears)\ **Post date:** [February 9, 2004, 1:24pm UTC](https://boards.straightdope.com/t/are-all-homo-sapiens-of-the-same-handedness/228262/1 "2004-02-09T13:24:19Z")
Replies to zut’s post: “Are all flatfish of the same handedness?” resulted in information that some species of flatfish were ‘ambidextrous’ some not, some rh, and some lh. I have read somewhere that all homo sapiens are not of the same handedness? That one person in several 10 thousands were lateralaly reversed right to left. Does anyone have certain knowledge of this? ---
**Author:** ![Achilles](https://avatars.discourse-cdn.com/v4/letter/a/dc4da7/32.png) [@Achilles](https://boards.straightdope.com/u/Achilles)\ **Post date:** [February 9, 2004, 1:29pm UTC](https://boards.straightdope.com/t/are-all-homo-sapiens-of-the-same-handedness/228262/2 "2004-02-09T13:29:13Z")
> [@spingears](#): > > Replies to zut’s post: “Are all flatfish of the same handedness?” resulted in information that some species of flatfish were ‘ambidextrous’ some not, some rh, and some lh. > > I have read somewhere that all homo sapiens are not of the same handedness? > That one person in several 10 thousands were lateralaly reversed right to left. > > Does anyone have certain knowledge of this? What are you talking about ? ---
**Author:** ![Richard\_Pearse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/richard_pearse/32/13144_2.png) [@Richard\_Pearse](https://boards.straightdope.com/u/Richard_Pearse)\ **Post date:** [February 9, 2004, 1:36pm UTC](https://boards.straightdope.com/t/are-all-homo-sapiens-of-the-same-handedness/228262/3 "2004-02-09T13:36:55Z")
Obviously some people are left handed, so I guess that’s not what you mean. Do you mean to ask whether some people are physically constructed as a mirror image to the rest of us? ---
**Author:** ![Achernar](https://avatars.discourse-cdn.com/v4/letter/a/e274bd/32.png) [@Achernar](https://boards.straightdope.com/u/Achernar)\ **Post date:** [February 9, 2004, 1:55pm UTC](https://boards.straightdope.com/t/are-all-homo-sapiens-of-the-same-handedness/228262/4 "2004-02-09T13:55:31Z")
The answer, strange as it is, is yes. It’s called Situs Inversus, and it’s found in about 1 in 10,000 people. ---
**Author:** ![Amp](https://avatars.discourse-cdn.com/v4/letter/a/6a8cbe/32.png) [@Amp](https://boards.straightdope.com/u/Amp)\ **Post date:** [February 9, 2004, 2:22pm UTC](https://boards.straightdope.com/t/are-all-homo-sapiens-of-the-same-handedness/228262/5 "2004-02-09T14:22:45Z")
[Situs Inversus](http://www.healthatoz.com/healthatoz/Atoz/ency/situs_inversus.html) This is pretty interesting. I’ve never heard of this condition. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [February 9, 2004, 2:25pm UTC](https://boards.straightdope.com/t/are-all-homo-sapiens-of-the-same-handedness/228262/6 "2004-02-09T14:25:36Z")
Are Situs Inversus people mostly left-handed? (NB: I’m not asking if left-handedness generally is _caused_ by Situs Inversus, but rather whether the handedness of the person is also one of the things that also gets reversed. ---
**Author:** ![Polycarp](https://avatars.discourse-cdn.com/v4/letter/p/82dd89/32.png) [@Polycarp](https://boards.straightdope.com/u/Polycarp)\ **Post date:** [February 9, 2004, 3:18pm UTC](https://boards.straightdope.com/t/are-all-homo-sapiens-of-the-same-handedness/228262/7 "2004-02-09T15:18:43Z")
> [@Mangetout](#): > > Are Situs Inversus people mostly left-handed? > > (NB: I’m not asking if left-handedness generally is _caused_ by Situs Inversus, but rather whether the handedness of the person is also one of the things that also gets reversed. No idea, really, but my guess would be that they are approximately 90% left-handed and 10% right-handed, the reversal of the proportion in “normal” people. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [February 9, 2004, 3:29pm UTC](https://boards.straightdope.com/t/are-all-homo-sapiens-of-the-same-handedness/228262/8 "2004-02-09T15:29:28Z")
That was my initial thought, but on reading that lined resourece, it sounds like the reversal may be limited to the organs in the abdomen - reversal of handedness (in this case) would seem to require something more system-wide than that. ---
**Author:** ![Really\_Not\_All\_That\_Bright](https://avatars.discourse-cdn.com/v4/letter/r/e8c25b/32.png) [@Really\_Not\_All\_That\_Bright](https://boards.straightdope.com/u/Really_Not_All_That_Bright)\ **Post date:** [February 9, 2004, 4:12pm UTC](https://boards.straightdope.com/t/are-all-homo-sapiens-of-the-same-handedness/228262/9 "2004-02-09T16:12:54Z")
I’d heard of people with heart and lungs shifted, but never anything like that. I wonder if _Situs Inversus_ also gives you two right feet. ---
**Author:** ![Richard\_Pearse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/richard_pearse/32/13144_2.png) [@Richard\_Pearse](https://boards.straightdope.com/u/Richard_Pearse)\ **Post date:** [February 10, 2004, 3:07am UTC](https://boards.straightdope.com/t/are-all-homo-sapiens-of-the-same-handedness/228262/10 "2004-02-10T03:07:52Z")
That would be _Situs Inversus Clutsus_ On actual left handedness, handedness would seem to be an effect of the construction of the brain. Does _Situs Inversus_ include a mirror of the brain’s construction as well?