I just skimmed through Human Biological Variation today. It was somewhat disappointing, the exploration of topics was often too superficial and I really didn't need a review of what mitosis, meiosis and Hardy-Weinberg Equilibrium were. They do collate some interesting data in the latter portion of the book, but the only one I'd like to pass on is about blood groups. This is one genetic trait which most of us happen to know about our own status in regards to, I'm an A, my father is a B and my mother is an A. But we are often under the impression that this is capricious, and the variation in frequency of the different alleles is a function of random genetic drift. This is not totally true. Below is a copy of table 4.6 from the book:
The worldwide frequencies are O at 63%, A at 21% and B at 16%. O is "recessive" in that an individual who is AO expresses A, and someone who is BO expresses B. Since I am an A, and my father is a B, he is probably a BO and I am an AO.
The ratios of blood groups derive from, for example: A:O = [A(patients) X O(controls)]/[O(patients) X A(controls)]
Stomach cancer, A:O - 1.22
Cancer of cervix, A:O - 1.13
Malignant tumors of salivary glands, A:O - 1.64
Nonmalignant tumoros of salivary glands A:O 2.02
Duodenal ulcers, O:A - 1.35
" ", O:A+B+AB - 1.33
Gastric ulcers, O:A - 1.17
" ", O:A+B+AB - 1.18
Rheumatic disease, A:O - 1.23
Diabetes mellitus, A:O - 1.07
" ", A+B+AB:O - 1.07
Ischemic heart disease, A:O - 1.18
" ", A+B+AB:O 1.17
Thromboembolic disease, A:O - 1.61
" ", A+B+AB:O - 1.60
Also,
* A study in Bangladesh has shown an assocation between cholera infection and blood group O.
* O have an advantage in syphylis, so if you are a slut, check your blood group!
* Mosquitos like the taste of O blood.
* There is some evidence that A individuals handle meat better while B prefer carbohydrates. Also, amusingly, B is a good predictor of "ponderality."
Anyway, just so you can do the conditional probabilities in your own life....
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Will you share this evidence?
Do they give 95% CIs for their odds ratios? :) I'd guess that none of those are significant.
I second Tara's comment...I just listened to an epidemiology student get ripped apart by a professor for not including the confidence intervals for some OR he had on a slide. Not pretty.
I'd guess that none of those are significant.
are you from the "it ain't significant if it ain't significant" school? :)
re: references,
kelso aj (1962) dietary differences: a possible selective mechanism in ABO blood group frequencies. southwestern lore 28:48-56
kelso aj and armelagos gj (1963) nutritional factors as selective agencies in the determination of ABO blood groups. southwestern lore 29:44-48
the title of the 'journal' does not inspire my confidence :)
but this,
beals kl, smith cl and kelso aj (1992) ABO phenotype and morphology. current anthropology 33:221-224 seems more legit (this is the one where you say B-folk are fatties)
though I don't know, it would be pretty lame for a textbook to include associations like that if they weren't significant.
Heh. I'm from the "odds ratios of that magnitude can easily be found due to chance alone" school. 1.07? C'mon... :)
well, i'm not going to look up the study frankly, so perhaps you are right. but, the authors seem to be a bit conservative overall in this book (other areas where i know more about the topic) so i am not willing to just assume they are including studies with tiny N.
i lied, i looked up the N by finding the table in the original book that the study was published. for the 1.07 ratio 15,778 patients and 612,819 controls. if anyone else is curious, vogel & motulsky, human genetics. sure you can find the source studies in that text if one is curious.
Stephen Molnar cites the greater susceptibility of Type A to plague and Type O to smallpox as the reason behind India's high levels of Type B.
I've ordered Human Biological Variation and look forward to reading it.
How informative was the section on the narrow sense heritability of the cephalic index?
Wow, i've never found out what my blood type is. In fact no one in my immediate family knows their blood type. Weird.
What on earth is "ponderality"?
they define it as mass to area ratio.
I was typed as B negative at birth, but B positive in adulthood. This is apparently fairly common, maybe having to do with changes in blood typing technology.
My wife Samantha was typed A positive at birth and B positive in adulthood. That is not so common.
Some people believe strange things about blood type and personality, especially in Japan, where it seems to be used similarly to astrological signs. There's also that flaky "Right For Your Blood Type Diet." I knew someone who was on it once; among other things, she could eat chicken but not turkey, or maybe it was the other way around.
Also, if you're A positive the Sycorax can hypnotize you with their mind rays.
My Dad is O-, the most common type in Ireland, and after Native Americans and Basques, the 3rd highest percentage in the world. My Mom is B+, very rare in Ireland. I'm O+.
I can't access those references, but a quick googling of AJ Kelso reveals that he appears to do mainstream research. I'm a little curious exactly what he says in Physical Anthropology that makes creationists like to quote him. Mind you, lots of legitimate researchers get co-opted by quacks, but I am curious...
That Eat Right 4 Your Type book is by Peter D'Adamo, N.D. He claims that Type A's should be vegetarians.
Re ''Eat Right For Your Blood Type Diet'', the main thing I took away from it was the idea that the A and B factors were late types - possibly linked with the rise of agriculture that is correlated with (or a marker for) the ability to consume grass products.
Wheat grains in Mesopotamia and Egypt would linked with a A type (and - my thoughts- possibly rice cultivation linked with B). These would be analogous to any markers for developed lactose tolerance in N. Europeans.
The upshot is that O blood indicates the absence of markers for grain tolerance, and is the original human type. People with O blood have an intolerance to grains and grass pollens and thus are prone to hay fever.
Pardon me while I sneeze. Also O types should eat more like a cave man - especially if that caveman had access to USDA choice beef.