# Study shows that blue-eyed people share a common, single ancestor. **URL:** \ **Category:** Miscellaneous and Personal Stuff I Must Share\ **Created:** [January 31, 2008, 10:43pm UTC](https://boards.straightdope.com/t/study-shows-that-blue-eyed-people-share-a-common-single-ancestor/435781 "2008-01-31T22:43:05Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Idle\_Thoughts](https://avatars.discourse-cdn.com/v4/letter/i/838e76/32.png) [@Idle\_Thoughts](https://boards.straightdope.com/u/Idle_Thoughts)\ **Post date:** [January 31, 2008, 10:43pm UTC](https://boards.straightdope.com/t/study-shows-that-blue-eyed-people-share-a-common-single-ancestor/435781/1 "2008-01-31T22:43:05Z")
Anyone see this today on MSN? [Scientists apparently say everyone with blue eyes has the same ancestor](http://www.msnbc.msn.com/id/22934464/wid/11915773?GT1=10815) I have blue eyes. So who all here am I related to! :eek: ---
**Author:** ![Mosier](https://avatars.discourse-cdn.com/v4/letter/m/7ea924/32.png) [@Mosier](https://boards.straightdope.com/u/Mosier)\ **Post date:** [January 31, 2008, 10:47pm UTC](https://boards.straightdope.com/t/study-shows-that-blue-eyed-people-share-a-common-single-ancestor/435781/2 "2008-01-31T22:47:28Z")
me, sort of. I have kind of grayish-blue eyes. ---
**Author:** ![WhyNot](https://avatars.discourse-cdn.com/v4/letter/w/c77e96/32.png) [@WhyNot](https://boards.straightdope.com/u/WhyNot)\ **Post date:** [January 31, 2008, 10:51pm UTC](https://boards.straightdope.com/t/study-shows-that-blue-eyed-people-share-a-common-single-ancestor/435781/3 "2008-01-31T22:51:33Z")
Hiya, cousin! ---
**Author:** ![Harmonious\_Discord](https://avatars.discourse-cdn.com/v4/letter/h/74df32/32.png) [@Harmonious\_Discord](https://boards.straightdope.com/u/Harmonious_Discord)\ **Post date:** [January 31, 2008, 10:54pm UTC](https://boards.straightdope.com/t/study-shows-that-blue-eyed-people-share-a-common-single-ancestor/435781/4 "2008-01-31T22:54:27Z")
Don’t they already claim that everybody is related after so many generation’s back? ---
**Author:** ![Flander](https://avatars.discourse-cdn.com/v4/letter/f/8c91f0/32.png) [@Flander](https://boards.straightdope.com/u/Flander)\ **Post date:** [January 31, 2008, 10:55pm UTC](https://boards.straightdope.com/t/study-shows-that-blue-eyed-people-share-a-common-single-ancestor/435781/5 "2008-01-31T22:55:23Z")
Mine change color. So sometimes we’re related, sometimes not. Like an Alabama prom date. ---
**Author:** ![guizot](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/guizot/32/3636_2.png) [@guizot](https://boards.straightdope.com/u/guizot)\ **Post date:** [January 31, 2008, 10:59pm UTC](https://boards.straightdope.com/t/study-shows-that-blue-eyed-people-share-a-common-single-ancestor/435781/6 "2008-01-31T22:59:56Z")
[QUOTE=Harmonious Discord] Don’t they already claim that everybody is related after so many generation’s back? [/QUOTE] I think you’re right, **Harmonious**. Anyway, I’m blue-eyed, and want to know if I have children with a brown-eyed woman, what kind of eyes should we expect? (I mean, are there percentages, odds, whatever…?) ---
**Author:** ![Anastasaeon](https://avatars.discourse-cdn.com/v4/letter/a/73ab20/32.png) [@Anastasaeon](https://boards.straightdope.com/u/Anastasaeon)\ **Post date:** [January 31, 2008, 11:00pm UTC](https://boards.straightdope.com/t/study-shows-that-blue-eyed-people-share-a-common-single-ancestor/435781/7 "2008-01-31T23:00:09Z")
Gray-blue here. And my husband, too. Oh, dear… :smack: ---
**Author:** ![Idle\_Thoughts](https://avatars.discourse-cdn.com/v4/letter/i/838e76/32.png) [@Idle\_Thoughts](https://boards.straightdope.com/u/Idle_Thoughts)\ **Post date:** [January 31, 2008, 11:04pm UTC](https://boards.straightdope.com/t/study-shows-that-blue-eyed-people-share-a-common-single-ancestor/435781/8 "2008-01-31T23:04:00Z")
That’s not good. Anyway, I don’t know the percentages of blue-eyed babies among dark and light-eyed people, but I DO know two blue-eyed people can only make blue-eyed children. No matter how many they have, they’ll always have blue eyes. ---
**Author:** ![Idle\_Thoughts](https://avatars.discourse-cdn.com/v4/letter/i/838e76/32.png) [@Idle\_Thoughts](https://boards.straightdope.com/u/Idle_Thoughts)\ **Post date:** [January 31, 2008, 11:09pm UTC](https://boards.straightdope.com/t/study-shows-that-blue-eyed-people-share-a-common-single-ancestor/435781/9 "2008-01-31T23:09:30Z")
**guizot** , to answer your question, I had to remember back to what I learned about it in biology. [http://www.accessexcellence.org/RC/VL/GG/recessive.html](http://www.accessexcellence.org/RC/VL/GG/recessive.html) Everyone has two chromosomes and the trait for blue eyes–let’s call that a little b. So b, then… The trait for brown eyes is usually depicted as a large B. There are three combinations a person could have. They’d either have a BB, Bb, or bb. Only a combo of bb chromosomes would make blue eyes. If you have blue eyes, you have bb. So you can ONLY give a small b to a child. Your SO, however, if she has brown eyes, might have be BB or Bb. Bb means she CARRIES the trait for blue eyes, but she wouldn’t have blue eyes since that one large B is dominant. So if you had four kids (and she is Bb), the chances that one of them (or two of them) would have blue eyes are fairly good. However if she carries the BB genes, there is no way any of your kids would have blue eyes. This is because they’d get a b from you, but a B from her…making their chromes Bb. So they’d carry the trait for blue eyes, but they’d have brown. There’s no way to tell (as far as I know) if she has BB or Bb. ---
**Author:** ![WhyNot](https://avatars.discourse-cdn.com/v4/letter/w/c77e96/32.png) [@WhyNot](https://boards.straightdope.com/u/WhyNot)\ **Post date:** [January 31, 2008, 11:10pm UTC](https://boards.straightdope.com/t/study-shows-that-blue-eyed-people-share-a-common-single-ancestor/435781/10 "2008-01-31T23:10:35Z")
[QUOTE=guizot] I think you’re right, **Harmonious**. Anyway, I’m blue-eyed, and want to know if I have children with a brown-eyed woman, what kind of eyes should we expect? (I mean, are there percentages, odds, whatever…?) [/QUOTE] Well, it depends on whether or not your brown-eyed girl has two brown genes or just one. If she has two brown-eye genes, all your kids will be brown eyed. If she has one brown-eye gene and one not-brown-eye gene (it’s not really a “blue” gene, it’s a not-brown gene), then statistically each offspring has a 25% chance of blue/green/yellow or hazel eyes\* and 75% chance of brown eyes. Of course, every kid gets the same odds, so it’s not unusual to have all brown eyed kids. \*Green, hazel and yellow irises are caused by lipid droplets in an otherwise “not-blue” eye. So if your sister has green eyes you can tease her that she’s got fat eyeballs. ---
**Author:** ![Rysto](https://avatars.discourse-cdn.com/v4/letter/r/ecccb3/32.png) [@Rysto](https://boards.straightdope.com/u/Rysto)\ **Post date:** [January 31, 2008, 11:18pm UTC](https://boards.straightdope.com/t/study-shows-that-blue-eyed-people-share-a-common-single-ancestor/435781/11 "2008-01-31T23:18:21Z")
My dad has blue eyes, so I’m related to all of you. ---
**Author:** ![Idle\_Thoughts](https://avatars.discourse-cdn.com/v4/letter/i/838e76/32.png) [@Idle\_Thoughts](https://boards.straightdope.com/u/Idle_Thoughts)\ **Post date:** [January 31, 2008, 11:18pm UTC](https://boards.straightdope.com/t/study-shows-that-blue-eyed-people-share-a-common-single-ancestor/435781/12 "2008-01-31T23:18:28Z")
So I’ve found five of my long lost cousin’s so far? : p Nice. ---
**Author:** ![askeptic](https://avatars.discourse-cdn.com/v4/letter/a/eb9ed0/32.png) [@askeptic](https://boards.straightdope.com/u/askeptic)\ **Post date:** [January 31, 2008, 11:28pm UTC](https://boards.straightdope.com/t/study-shows-that-blue-eyed-people-share-a-common-single-ancestor/435781/13 "2008-01-31T23:28:00Z")
[QUOTE=Idle Thoughts] There’s no way to tell (as far as I know) if she has BB or Bb. [/QUOTE] Sure there is. Look at the kids eyes if they are blue you will know she must be Bb. Of course, that won’t help if you want to know before the kid is born… ---
**Author:** ![HazelNutCoffee](https://avatars.discourse-cdn.com/v4/letter/h/ac91a4/32.png) [@HazelNutCoffee](https://boards.straightdope.com/u/HazelNutCoffee)\ **Post date:** [January 31, 2008, 11:29pm UTC](https://boards.straightdope.com/t/study-shows-that-blue-eyed-people-share-a-common-single-ancestor/435781/14 "2008-01-31T23:29:23Z")
[QUOTE=askeptic] Sure there is. Look at the kids eyes if they are blue you will know she must be Bb. Of course, that won’t help if you want to know before the kid is born… [/QUOTE] I’m confused. Wouldn’t Bb manifest as brown? ---
**Author:** ![WhyNot](https://avatars.discourse-cdn.com/v4/letter/w/c77e96/32.png) [@WhyNot](https://boards.straightdope.com/u/WhyNot)\ **Post date:** [January 31, 2008, 11:31pm UTC](https://boards.straightdope.com/t/study-shows-that-blue-eyed-people-share-a-common-single-ancestor/435781/15 "2008-01-31T23:31:43Z")
[QUOTE=HazelNutCoffee] I’m confused. Wouldn’t Bb manifest as brown? [/QUOTE] He means if the kids - any of them - have blue eyes, \*she \* (the brown-eyed mother) must be a Bb, or carrying a hidden recessive gene. The kid, of course, will be bb. ---
**Author:** ![Waenara](https://avatars.discourse-cdn.com/v4/letter/w/50afbb/32.png) [@Waenara](https://boards.straightdope.com/u/Waenara)\ **Post date:** [January 31, 2008, 11:33pm UTC](https://boards.straightdope.com/t/study-shows-that-blue-eyed-people-share-a-common-single-ancestor/435781/16 "2008-01-31T23:33:17Z")
[QUOTE=Harmonious Discord] Don’t they already claim that everybody is related after so many generation’s back? [/QUOTE] Yup. There is a [most recent common ancestor](http://en.wikipedia.org/wiki/Most_recent_common_ancestor) (MRCA) of all surviving humans. And that’s just the _most recent_ common ancestor - there may be several common ancestors further back in time (e.g. the one with blue eyes). > [@](#): > > The existence of an MRCA does not imply existence of a population bottleneck or first couple. The MRCA of everyone alive today could have co-existed with a large human population, most of whom either have no living descendants today or else are ancestors of a subset of people alive today. This seemingly paradoxical phenomenon can be easily explained, if the nature of lineage is taken into account. The MRCA is usually thought to have lived in Paleolithic times, but some estimates put them in historical times: > [@](#): > > Depending on the survival of isolated lineages without admixture from Modern migrations and taking into account long-isolated peoples, such as historical tribes in central Africa, Australia and remote islands in the South Pacific, the human MRCA was generally assumed to have lived in the Paleolithic period. > > However, Rohde, Olson, and Chang (2004)[3], using a non-genetic model, estimated that the MRCA of all living humans may have lived within historical times (3rd millennium BC to 1st millennium AD). Rohde (2005)[5] refined the simulation with parameters from estimated historical human migrations and of population densities. For conservative parameters, he pushes back the date for the MRCA to the 6th millennium BC (p. 20), but still concludes with a “surprisingly recent” estimate of a MRCA living in the second or first millennium BC (p. 27). ---
**Author:** ![Northern\_Thalia](https://avatars.discourse-cdn.com/v4/letter/n/ba8739/32.png) [@Northern\_Thalia](https://boards.straightdope.com/u/Northern_Thalia)\ **Post date:** [February 1, 2008, 12:04am UTC](https://boards.straightdope.com/t/study-shows-that-blue-eyed-people-share-a-common-single-ancestor/435781/17 "2008-02-01T00:04:39Z")
[QUOTE=guizot] I think you’re right, **Harmonious**. Anyway, I’m blue-eyed, and want to know if I have children with a brown-eyed woman, what kind of eyes should we expect? (I mean, are there percentages, odds, whatever…?) [/QUOTE] Here’s a really cool site that you can put your eye colour, your parents’, your partner’s, and their parents’ and it will figure out the probability of the eye colour of your children. [http://museum.thetech.org/ugenetics/eyeCalc/eyecalculator.html](http://museum.thetech.org/ugenetics/eyeCalc/eyecalculator.html) ---
**Author:** ![Ferret\_Herder](https://avatars.discourse-cdn.com/v4/letter/f/e47774/32.png) [@Ferret\_Herder](https://boards.straightdope.com/u/Ferret_Herder)\ **Post date:** [February 1, 2008, 12:46am UTC](https://boards.straightdope.com/t/study-shows-that-blue-eyed-people-share-a-common-single-ancestor/435781/18 "2008-02-01T00:46:37Z")
Hey relatives! ---
**Author:** ![goldenmean1975](https://avatars.discourse-cdn.com/v4/letter/g/7993a0/32.png) [@goldenmean1975](https://boards.straightdope.com/u/goldenmean1975)\ **Post date:** [February 1, 2008, 3:08am UTC](https://boards.straightdope.com/t/study-shows-that-blue-eyed-people-share-a-common-single-ancestor/435781/19 "2008-02-01T03:08:08Z")
me too mine are greenish but way more blue than green ---
**Author:** ![GingerOfTheNorth](https://avatars.discourse-cdn.com/v4/letter/g/cdc98d/32.png) [@GingerOfTheNorth](https://boards.straightdope.com/u/GingerOfTheNorth)\ **Post date:** [February 1, 2008, 3:10am UTC](https://boards.straightdope.com/t/study-shows-that-blue-eyed-people-share-a-common-single-ancestor/435781/20 "2008-02-01T03:10:08Z")
I’m blue, but my husband has fat old green eyes. Both kids are blue. [Next page](https://boards.straightdope.com/t/study-shows-that-blue-eyed-people-share-a-common-single-ancestor/435781.md?page=2)