# Why is type B blood more rare than type A blood? **URL:** \ **Category:** Factual Questions\ **Created:** [December 14, 2003, 9:25pm UTC](https://boards.straightdope.com/t/why-is-type-b-blood-more-rare-than-type-a-blood/218999 "2003-12-14T21:25:06Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![loinburger](https://avatars.discourse-cdn.com/v4/letter/l/db5fbb/32.png) [@loinburger](https://boards.straightdope.com/u/loinburger)\ **Post date:** [December 14, 2003, 9:25pm UTC](https://boards.straightdope.com/t/why-is-type-b-blood-more-rare-than-type-a-blood/218999/1 "2003-12-14T21:25:06Z")
According to a quick Google search, type B blood is significantly more rare (rarer? is that a word?) than type A blood. Specifically, about 39% of the population is either A+ or A-, while only about 11% of the population is either B+ or B-. What gives? If the genes for the A and B blood types are both dominant, then shouldn’t their distributions be much more similar? ---
**Author:** ![Akatsukami](https://avatars.discourse-cdn.com/v4/letter/a/ea666f/32.png) [@Akatsukami](https://boards.straightdope.com/u/Akatsukami)\ **Post date:** [December 14, 2003, 10:09pm UTC](https://boards.straightdope.com/t/why-is-type-b-blood-more-rare-than-type-a-blood/218999/2 "2003-12-14T22:09:42Z")
The gene for type B appears to be a (relatively) recent mutation; it is virtually non-existent in Amerinds and Na-Denes, generally accepted to have been isolated from the Eastern Hemisphere for thousands of years. The frequency of type B, moreover, seems to form a smooth function as a distance from a locus in Asia, where it is considered to have originated. The answer, then, is that the type B genotype has _not yet_ had time to spread generally into the human gene pool. ---
**Author:** ![friedo](https://avatars.discourse-cdn.com/v4/letter/f/8edcca/32.png) [@friedo](https://boards.straightdope.com/u/friedo)\ **Post date:** [December 14, 2003, 11:02pm UTC](https://boards.straightdope.com/t/why-is-type-b-blood-more-rare-than-type-a-blood/218999/3 "2003-12-14T23:02:28Z")
What in the hell are “Na-Denes?” ---
**Author:** ![rjk](https://avatars.discourse-cdn.com/v4/letter/r/ed655f/32.png) [@rjk](https://boards.straightdope.com/u/rjk)\ **Post date:** [December 14, 2003, 11:19pm UTC](https://boards.straightdope.com/t/why-is-type-b-blood-more-rare-than-type-a-blood/218999/4 "2003-12-14T23:19:21Z")
The Na-Dene peoples are North American natives living along the northern part of the West Coast (BC and up into Alaska). They include Haida and Tlingit tribes, IIRC, and probably more. Their culture and languages are different from most other NA natives, so they get their own group. ---
**Author:** ![Polycarp](https://avatars.discourse-cdn.com/v4/letter/p/82dd89/32.png) [@Polycarp](https://boards.straightdope.com/u/Polycarp)\ **Post date:** [December 14, 2003, 11:19pm UTC](https://boards.straightdope.com/t/why-is-type-b-blood-more-rare-than-type-a-blood/218999/5 "2003-12-14T23:19:25Z")
> [@](#): > > \*Originally posted by friedo \* > \*\*What in the hell are “Na-Denes?” \*\* Well, Barb and I went to school with a girl named Nadine, but I suspect what **Akatsukami** is referring to is the Native American/First Nations group called Na-Denes, AKA Athapaskans, who are ethnically and linguistically significantly different from the remainder of NA/FN peoples. (“Lumper” glottochronologists hypothecate a common ancestry for all Western Hemisphere pre-Columbian languages except Innuit/Aleut and Na-Dene groups.) **‘Katsu’** clearly is trying to preserve the distinction, much like someone addressing a common trait in Europe and South Asia by saying “Indo-European peoples and the Basques” – making clear that he’s aware of the distinction but intends to include the Basques in his discussion anyway. ---
**Author:** ![Akatsukami](https://avatars.discourse-cdn.com/v4/letter/a/ea666f/32.png) [@Akatsukami](https://boards.straightdope.com/u/Akatsukami)\ **Post date:** [December 14, 2003, 11:27pm UTC](https://boards.straightdope.com/t/why-is-type-b-blood-more-rare-than-type-a-blood/218999/6 "2003-12-14T23:27:48Z")
Those American aboriginals who speak (or spoke) Na-Dene languages: primarily Athabaskan, but including other languages of the American and Canadian PNW, and outliers such as Apache and Navajo. Na-Denes are linguistically and genetically quite distinct from other non-Eskimo Americans (“Amerinds”), and it is generally accepted that they stem from a quite migration, several thousand years after the Amerind expansion into the Americas (probably before 9,000 BCE, from a staging area in Beringia and western Alaska). “Na-Dene”, incidentally is three syllables: approximately “NAH-dey-nee”. ---
**Author:** ![friedo](https://avatars.discourse-cdn.com/v4/letter/f/8edcca/32.png) [@friedo](https://boards.straightdope.com/u/friedo)\ **Post date:** [December 14, 2003, 11:37pm UTC](https://boards.straightdope.com/t/why-is-type-b-blood-more-rare-than-type-a-blood/218999/7 "2003-12-14T23:37:40Z")
Groovy. ---
**Author:** ![loinburger](https://avatars.discourse-cdn.com/v4/letter/l/db5fbb/32.png) [@loinburger](https://boards.straightdope.com/u/loinburger)\ **Post date:** [December 14, 2003, 11:46pm UTC](https://boards.straightdope.com/t/why-is-type-b-blood-more-rare-than-type-a-blood/218999/8 "2003-12-14T23:46:35Z")
> [@](#): > > \*Originally posted by Akatsukami \* > The gene for type B appears to be a (relatively) recent mutation; it is virtually non-existent in Amerinds and Na-Denes, generally accepted to have been isolated from the Eastern Hemisphere for thousands of years. The frequency of type B, moreover, seems to form a smooth function as a distance from a locus in Asia, where it is considered to have originated. > > The answer, then, is that the type B genotype has _not yet_ had time to spread generally into the human gene pool. Ah, that explains it then. On a semi-related note: are there any significant phenotypic (is that a word?) differences between the different blood types? I.e., is there any advantage to being, say, O+, or B-, or whatever, aside from the ability to receive transfusions from a greater or lesser number of people? ---
**Author:** ![Akatsukami](https://avatars.discourse-cdn.com/v4/letter/a/ea666f/32.png) [@Akatsukami](https://boards.straightdope.com/u/Akatsukami)\ **Post date:** [December 14, 2003, 11:55pm UTC](https://boards.straightdope.com/t/why-is-type-b-blood-more-rare-than-type-a-blood/218999/9 "2003-12-14T23:55:06Z")
> [@](#): > > \*Originally posted by loinburger \* > \*\*On a semi-related note: are there any significant phenotypic (is that a word?) differences between the different blood types? I.e., is there any advantage to being, say, O+, or B-, or whatever, aside from the ability to receive transfusions from a greater or lesser number of people? \*\* No, there is no detectable difference in the A-B-O or Rh blood groups. ---
**Author:** ![Smeghead](https://avatars.discourse-cdn.com/v4/letter/s/f1d935/32.png) [@Smeghead](https://boards.straightdope.com/u/Smeghead)\ **Post date:** [December 15, 2003, 7:41am UTC](https://boards.straightdope.com/t/why-is-type-b-blood-more-rare-than-type-a-blood/218999/10 "2003-12-15T07:41:02Z")
> [@](#): > > \*Originally posted by loinburger \* > \*\*If the genes for the A and B blood types are both dominant, then shouldn’t their distributions be much more similar? \*\* When there’s no selective pressure, as in the case of blood type, dominance or recessiveness has absolutely nothing to do with distribution. You could have a dominant trait that remains extremely rare or a recessive trait that is extremely common. They’re totally unrelated. ---
**Author:** ![KarlGauss](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/karlgauss/32/3713_2.png) [@KarlGauss](https://boards.straightdope.com/u/KarlGauss)\ **Post date:** [December 15, 2003, 11:09am UTC](https://boards.straightdope.com/t/why-is-type-b-blood-more-rare-than-type-a-blood/218999/11 "2003-12-15T11:09:56Z")
> [@](#): > > is there any advantage to being, say, O+, or B-, or whatever, aside from the ability to receive transfusions from a greater or lesser number of people? I am not aware of any advantages, but there may be a disadvantage. Specifically, [people with type A blood are more likely to develop various cancers](http://illness.altmedangel.com/canblood.htm). ---
**Author:** ![tanookie](https://avatars.discourse-cdn.com/v4/letter/t/48db29/32.png) [@tanookie](https://boards.straightdope.com/u/tanookie)\ **Post date:** [December 15, 2003, 3:58pm UTC](https://boards.straightdope.com/t/why-is-type-b-blood-more-rare-than-type-a-blood/218999/12 "2003-12-15T15:58:49Z")
There is a disadvantage for a woman who is RH - to have children with a man who is RH + If the children of an RH - mother have RH + blood it is possible for the mother to build up antibodies against her children’s blood. They screen for this today and the treatment options are very good but it can be very bad for the babies if not detected in time. [RH disease](http://www.babycenter.com/expert/2709.html) ---
**Author:** ![Grey](https://avatars.discourse-cdn.com/v4/letter/g/b782af/32.png) [@Grey](https://boards.straightdope.com/u/Grey)\ **Post date:** [December 15, 2003, 4:17pm UTC](https://boards.straightdope.com/t/why-is-type-b-blood-more-rare-than-type-a-blood/218999/13 "2003-12-15T16:17:44Z")
Some more [GQ Blood type](http://boards.straightdope.com/sdmb/showthread.php?s=&threadid=191936&highlight=blood+types) information. ---
**Author:** ![ckelley110105](https://avatars.discourse-cdn.com/v4/letter/c/b5e925/32.png) [@ckelley110105](https://boards.straightdope.com/u/ckelley110105)\ **Post date:** [July 24, 2011, 2:31pm UTC](https://boards.straightdope.com/t/why-is-type-b-blood-more-rare-than-type-a-blood/218999/14 "2011-07-24T14:31:08Z")
I have type AB- guess I could be doomed if I needed a blood transfusion. They say rh- came from the annunaki. Who knows lol ---
**Author:** ![Nametag](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/nametag/32/406_2.png) [@Nametag](https://boards.straightdope.com/u/Nametag)\ **Post date:** [July 24, 2011, 2:50pm UTC](https://boards.straightdope.com/t/why-is-type-b-blood-more-rare-than-type-a-blood/218999/15 "2011-07-24T14:50:13Z")
> [@ckelley110105](#): > > I have type AB- guess I could be doomed if I needed a blood transfusion. They say rh- came from the annunaki. Who knows lol No, you can safely get a transfusion from anyone without RH factor. Anyone who needs a transfusion and can only get it from you (on a desert island or something) would most likely be screwed, however. ---
**Author:** ![Taomist](https://avatars.discourse-cdn.com/v4/letter/t/53a042/32.png) [@Taomist](https://boards.straightdope.com/u/Taomist)\ **Post date:** [July 24, 2011, 8:10pm UTC](https://boards.straightdope.com/t/why-is-type-b-blood-more-rare-than-type-a-blood/218999/16 "2011-07-24T20:10:05Z")
> [@tanookie](#): > > There is a disadvantage for a woman who is RH - to have children with a man who is RH + > > If the children of an RH - mother have RH + blood it is possible for the mother to build up antibodies against her children’s blood. They screen for this today and the treatment options are very good but it can be very bad for the babies if not detected in time. > > [RH disease](http://www.babycenter.com/expert/2709.html) My mom’s B- and I’m B+. Guess we got lucky; I was her first, and she didn’t even see a doctor until after her water broke. > [@](#): > > Rh disease (also known as Rh (D) disease, Rhesus incompatibility, Rhesus disease, RhD Hemolytic Disease of the Newborn, Rhesus D Hemolytic Disease of the Newborn or RhD HDN) is one of the causes of hemolytic disease of the newborn (HDN). The disease ranges from mild to severe, and typically occurs only in some second or subsequent pregnancies of Rh negative women where the fetus’ father is Rh positive,leading to a Rh+ pregnancy. During birth, the mother may be exposed to the infant’s blood, and this causes the development of antibodies, which may affect the health of subsequent Rh+ pregnancies. I’ll have to ask if she had any issues with later offspring, as it appears the first pregnancy doesn’t often cause this. I shoulda read first! ---
**Author:** ![kittenblue](https://avatars.discourse-cdn.com/v4/letter/k/ba8739/32.png) [@kittenblue](https://boards.straightdope.com/u/kittenblue)\ **Post date:** [July 24, 2011, 10:41pm UTC](https://boards.straightdope.com/t/why-is-type-b-blood-more-rare-than-type-a-blood/218999/17 "2011-07-24T22:41:17Z")
I’m Bneg and have been asked a couple times to be a direct donor. And none of my ancestors came from Asia, to my knowledge. Am I misunderstanding Akatsukami’s post? ---
**Author:** ![Darth\_Panda](https://avatars.discourse-cdn.com/v4/letter/d/ee7513/32.png) [@Darth\_Panda](https://boards.straightdope.com/u/Darth_Panda)\ **Post date:** [July 24, 2011, 10:57pm UTC](https://boards.straightdope.com/t/why-is-type-b-blood-more-rare-than-type-a-blood/218999/18 "2011-07-24T22:57:46Z")
From a selfish point of view, AB+ is the ‘best’ blood type - you can receive a transfusion from anyone (generally speaking). ---
**Author:** ![RadicalPi](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/radicalpi/32/9806_2.png) [@RadicalPi](https://boards.straightdope.com/u/RadicalPi)\ **Post date:** [July 24, 2011, 11:27pm UTC](https://boards.straightdope.com/t/why-is-type-b-blood-more-rare-than-type-a-blood/218999/19 "2011-07-24T23:27:25Z")
Here’s a map of the ABO situation, for what it’s worth: [http://anthro.palomar.edu/vary/vary\_3.htm](http://anthro.palomar.edu/vary/vary_3.htm) ---
**Author:** ![Smeghead](https://avatars.discourse-cdn.com/v4/letter/s/f1d935/32.png) [@Smeghead](https://boards.straightdope.com/u/Smeghead)\ **Post date:** [July 25, 2011, 12:10am UTC](https://boards.straightdope.com/t/why-is-type-b-blood-more-rare-than-type-a-blood/218999/20 "2011-07-25T00:10:55Z")
Just pointing out that this thread is eight years old, and some incredibly handsome intelligent guy explained way back then why a dominant gene could be rare. [Next page](https://boards.straightdope.com/t/why-is-type-b-blood-more-rare-than-type-a-blood/218999.md?page=2)