Race mixing leading to obesity?

i-659886966c63d8fbd172e0c9ad0c0013-kristin-kreuk-picture-1.jpgMy post from a few weeks ago, Why does race matter for women?, elicited a lot of response (made it to the front page of Digg). Most of the open public discourse on race is bracketed in a few coarse frameworks; it is a social construction, and no one cares who is truly enlightened anymore, white racism keeps people of color down, etc. Though of utility in sloganeering I think most of these generalizations are such half-approximations that they mislead a great deal of time. So for example the interesting repeated finding that women in the United States are consistently more race conscious in partner selection than males in terms of avowed and revealed preferences (the study I posted on was just the most thorough, there were a few other prior surveys that showed the same general surprising finding). Public dialogue and discussion doesn't operate much with the assumption that women are the repository of race consciousness and purity, that seems a rather retrograde view among White People, but something close to it seems to operate in the day to day (as many 25 year old Asian American male virgins might attest to).

With that in mind, Yann points me to a new paper, Prevalence of obesity in multi-racial vs. mono-racial individuals:

The sample included 215,000 adults who reported one or more ethnicities, height, weight, and other characteristics through a mailed survey.
...
The highest age-adjusted prevalence of overweight (BMI greater than or equal to 25) was in Hawaiian/Latino men (88% ; n = 41) and black/Latina women (74.5% ; n = 79), and highest obesity (BMI greater than or equal to 30) rates were in Hawaiian/Latino men (53.7% ; n = 41) and Hawaiian women (39.2% , n = 1,247). The prevalence estimates for most admixed groups were similar to or higher than the average of the prevalences for the ethnic groups with whom they shared common ethnicities. For instance, the prevalence of overweight/obesity in five ethnic admixtures--Asian/white, Hawaiian/white, Hawaiian/Asian, Latina/white, and Hawaiian/Asian/white ethnic admixtures--was significantly higher (P
...
The identification of individuals who have a high-risk ethnic admixture is important not only to the personal health and well-being of such individuals, but could also be important to future efforts in order to control the epidemic of obesity in the United States.

i-6c0297de06ec38da10ebfb70553d4e0d-gabrielle-anwar-1-sized.jpgEarly in the 20th century the dominant cultural norm was that race consciousness was normal, natural, and that hybridization was "against nature." Charles Davenport, one of the early directors of Cold Spring Harbor Laboratory, unsurprisingly found that mixed-race individuals in Jamaica were less physiologically fit than monoracial individuals (from what I recall he generally appealed to morphometric data). He found what he wanted to find. Biology is a science with a lot of variation, just pick the data which confirm your model and pretend you aren't selection biasing. If the people you want to convince don't know any better, then all the best for you!

Today we have an inverted situation. The biologist Armand Leroi writes articles making the case that a racially mixed woman is the most beautiful individual because between population hybridization results in the masking of more deleterious alleles. The logic here is simple; consider something like cystic fibrosis or a sickle cell anemia predisposition. Since these recessive diseases occur within subpopulations, breeding out will mask more of them. After all, one can posit a number of recessive expressing genotypes with a very small decrement of fitness. The further you breed out the more likely you're to complement so that these deleterious alleles are masked by higher fitness alleles.

An important point here is that hybrid offspring might not necessarily be superior to both parents in trait value, rather, they'll consistently exceed the expectation based on additive effects across both parents. By way of illustration, imagine that you have a population where you normalize the mean height as 1 and another with a mean height as 0.8. Assume perfect heritability. Assume that they're of the same size and sex ratio and they randomly mate. The new hybrid population should have a mean height of 0.90 because you're simply averaging out genetic potentialities. If the mean height turns out to be 0.95 you know that there are some dominance effects on work which operate outside of the additive assumption.

i-ba32b4a7f7eb71d752a3c92124bcd361-amerie21.jpgIn any case, that's the outline, and because of integrationist social norms I regularly get comments on these boards praising the value of hybrid vigor. But reality isn't what we wish it to be, it is what is, at least to the best of our knowledge. It is seems likely hybrid vigor and fitness as it relates to crosses across degrees of relatedness manifests in a more complex and nuanced manner than a simple linear extrapolation. Obviously sibling-sibling mating results in a high rates of unmasking of deleterious alleles. The issues around cousin marriage are less dire and more subtle; though first cousin matings seem to exhibit more problems than outbred matings, there is some data which implies that if the other individual is extremely distantly related then fertility starts dropping.

There are complicated confounds here. For example, not everything is genetic, the way human psychological and social networks operate there might be biases in the nature of how people relate to each other. Norms matter in terms of comfort and communication. Additionally, much of the likely counterbalance toward the masking of deleterious isn't genetically arcane, it is likely simple immune incompatibilities between mother and fetus. Those who are closely related are immunologically more likely to be similar as a matter of course, those who are distantly related are likely to be less related. Multiracial children have problems finding immune matches because of the relative rarity of their genotypic combinations. At the reductio ad absurdum we know that a human male mating with a female chimp isn't going to produce a super-homonoid who has the physical strength of the chimp and the mental acuity of the human; rather, chimp ova have physiological defenses which prevent even the penetration of human sperm.

Finally, there is the possibility that there are interaction effects in the genetic background of populations which will emerge only through crossing. Just as allele A may mask allele B, allele A on locus 1 may not interact positively with allele B on locus 2, and variations in gene frequency across populations may result in differences in the rate at which these incompatibilities will crop up. A paper from a few years ago illustrates this possibility well, A variant of the gene encoding leukotriene A4 hydrolase confers ethnicity-specific risk of myocardial infarction:

Variants of the gene ALOX5AP (also known as FLAP) encoding arachidonate 5-lipoxygenase activating protein are known to be associated with risk of myocardial infarction. Here we show that a haplotype (HapK) spanning the LTA4H gene encoding leukotriene A4 hydrolase, a protein in the same biochemical pathway as ALOX5AP, confers modest risk of myocardial infarction in an Icelandic cohort. Measurements of leukotriene B4 (LTB4) production suggest that this risk is mediated through upregulation of the leukotriene pathway. Three cohorts from the United States also show that HapK confers a modest relative risk (1.16) in European Americans, but it confers a threefold larger risk in African Americans. About 27% of the European American controls carried at least one copy of HapK, as compared with only 6% of African American controls. Our analyses indicate that HapK is very rare in Africa and that its occurrence in African Americans is due to European admixture. Interactions with other genetic or environmental risk factors that are more common in African Americans are likely to account for the greater relative risk conferred by HapK in this group.

i-b7cd844024892228d78f862336b63d04-rihanna-picture.jpgIn plain English the fact that African Americans are an admixed population is causing a problematic interaction here; HapK does not exist at high frequencies in the original African genetic background. When introduced to that genetic background selection starts operating. That's evolution. Humans have been evolving a lot over the past 50,000 years, no surprise that various groups have their own quirks and not everything fits together well.

One of the things I like to point out is that fundamentally human genetics is not blending. The admixture of a black skinned and white skinned population will not result in a uniformly brown skinned population. Given a large population base the original extant variance will still be on evidence though the central tendency will be toward a brownish median. In other words, admixture does not eliminate diversity but retains and even extends it on a within population level. One of the arguments that have cropped up over the years in evolutionary biology is whether fitness is heritable, and what the variance in fitness is. If fitness is heritable and exhibits variance, we might expect that the full range of variance would still manifest in hybrid populations. Not only that, it is known that hybrid populations can exhibit surprising and novel genetic combinations. Perhaps one might expect then that hybridization might lead both to very low fitness individuals and to very high fitness individuals? The Ãbermensch and Untermensch might be in the future.

In any case, back to fatitude. What's up with that? First, yeah, there might be selection issues with who likes to hit-it-it with other races in Hawaii, etc. There might be big sociocultural confounds, I don't know. Perhaps racially mixed kids get a lot of crap from both sides and they stuff their faces because of depression and stress. But here's an idea, in Why Some Like It Hot: Food, Genes, and Cultural Diversity, the argument is made that some health problems like obesity arise when people shift from culturally specific foods to mass market consumable products. Different populations have different propensities toward different food stuffs; e.g., consider the amylase and lactase examples. Perhaps mixed-race children because of their bicultural background are exposed to a hodge-podge of dietary regimes which aren't optimal to their genetic makeup, which are relatively recent and so might not have a ready made cuisine?

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It sure would have been nice if they had been able to gather information on the obesity of the parents of the sampled individuals, and the race of the parents with respect to gender. Heck, maybe women become more likely to date outside their race when they are fat. I've seen plenty of anecdotes of white chubbers turning to black guys when they got no attention from white guys black guys. That a way that it wasn't the race-mixing that caused the obesity but the other way around.

The only category I would question is the asian/white category. Does it really shock anyone that the polynesian category shows obesity? I know it's a generalization but polynesians do tend to be very large. Why, I don't know.
The asian/white category may also have some confounding factors. Namely that it's probably 90% white men and asian women. What sort of self selection is there in this category? If you've ever been to the bars in asia, you know that the men who go there are not exactly in the best shape. I realize this is massive prejudice on my part, but I'm just guessing right now. What is the breakdown of the white/asian column?

Does it really shock anyone that the polynesian category shows obesity?

let's put out thinking caps on, shall we? the key is that the mixed category *is fatter*

Namely that it's probably 90% white men and asian women.

no, we have data for this stuff. see here. looking up stuff is good for you. try it (or don't comment).

Interesting. I have a white-asian (thai) mixed sister-in-law, and she's pretty big. My brother is white, tall (6'2), and moderately over-weight.

Now, as long as I've known her she's expressed near hatred for most asian men. She especially hates filipinos -- she says they try too hard to be like Americans. She also kinda hates most Americans, she's very left-wing. I usually like most Filipinos I meet, perhaps because they seem so all-American.

But she's also tall (almost 6 ft), so she towers over most asian guys. She also has a very ... brassy personality. Kinda crude and sarcastic ... the opposite of the shy, dutiful asian girl.

I don't know how universal this is, but most American women want their guy to be taller than they are. They also don't want to weigh more than the guy. But I think height is more important to them. Makes them feel more feminine.

Her Dad is a hilarious ultra right wing (in the capitalist war-monger sense of right-wing, not the baby Jesus and family sense) State dept guy, but who can speak like 6 asian languages, who kept various concubines scattered throughout southeast asia. Got a couple pregnant. Raised one. Eventually brought a Vietnamese woman and her family stateside, getting married for the first time in his late 60s. I think his Vietnamese wife is just biding her time until he dies. She's quite young still. He bought her an SUV and some new boobs, so she's ready to take on the world.

She also has a very ... brassy personality. Kinda crude and sarcastic ... the opposite of the shy, dutiful asian girl.

Um, don't now of too many Asian women, do you? (In private, that is....)

Better be careful, you might give Zuska a tummy-ache.

There could be a much simpler social confound here - namely self-selection for "don't care what other people think." Lots of social pressure to be thin these days. Lots of social pressure against race-mixing 30something years ago.

So the mavericks are breeding more mavericks.

(Agree about the asian woman comment. Not in my neighborhood.)

An interesting thing would be to cross-reference this data against the distribution of ocesity and racial group representation around the country. For example, how do mixed-race individuals compare to the general state-wide population and the state-wide obesity rates for their stated racial lineages within-state?

Another potentially interesting thing would be to see how much variation there is in obesity of particular mixed-race populations between states. For example to asian/whites from Hawaii differ fro asian/whites in California? Part of this analysis could look at how racial prevalence might affect obesity rates (attempting to answer the "racially mixed kids get a lot of crap from both sides and they stuff their faces because of depression and stress" hypothesis posed by razib).

Just some thoughts. Of course, I'm not volunteering...

remember that hawaii has the u most historically old group of "mixed" people in the USA. i think around 20% of hawaiians identify as mixed (more are).

I think there's a very, very simple answer here: the genes that create obesity (by increasing efficiency of energy use) are actually genes that have been "sought after" since humans existed. These people would survive much better in previous centuries--obesity is a result of abundant food.

Nonsense, fat people are food for the tribe in hard times. They are easier to catch than children and much tastier than grandma. The true reason behind their existance must be kept from them so they don't diet and doom us all.

For example, not everything is genetic, the way human psychological and social networks operate there might be biases in the nature of how people relate to each other.

"Not everything"? How about, when it comes to complex human social behavior, "hardly anything"?

It still seems like an Asian / Polynesian thing, since they're the groups who show up most in the hybrid depression category; it doesn't appear to generalize to interracials. You'd expect to see Black-Other biracials there, since Blacks have high rates of obesity, adopted agriculture only recently, etc. Same for Latin Americans.

If I were a moron who wanted to sell books, I'd combine two sexy ideas into one big explanation: these interracials are showing off their hybrid vigor for facial attractiveness by choosing to eat worse or work out less, an instance of the Handicap Principle. "I'm such an interracial hottie, I can blimp out and still look OK."

BTW, 1/4 Japanese, 3/4 White, and BMI = 20.5, bitches!!!

"Not everything"? How about, when it comes to complex human social behavior, "hardly anything"?

that's wrong.

The data Razib linked to is not the data used in the Nature study, as far as I can see. It could be, I have no way of knowing. That's why I would like to know, but let's face it I'm too lazy to find out just to add a comment on a blog.

What evidence is there one way or the other?

the verbal terms are too vague, so i'm not going to elucidate. but, i tend to take the evidence for additive genetic variance in behavior genetic data seriously; ergo, in that light, you're wrong. OTOH, if you don't take it seriously, you're right.

so the difference, if any exists, is far upstream of the particular assertion you're making....

Dude, I have no idea what you are talking about. Can you just point me to the evidence you seem to be alluding to that provides a quantitative estimate of the genetic contribution to complex human social behavior?

Google "behavior genetics" -- genetic differences contribute to differences in IQ and personality traits, the basis for complex (IQ) social behavior (personality). Don't worry, though: you can still shift the goalposts by claiming the results aren't complex enough, and be able to sleep at night.

This article is supported by shotty evidence at best. Most of which is masked by long-winded bullshit.

Interesting study to say the least. I wish I had the dime to drop on the whole article. So just some notes:

The biggest problem is with the use of "self-identified" social statistics. Racial self-identification is a pretty complex thing in Hawaii. The number of actual unmixed Hawaiians is vanishingly rare, despite that, census records have around 140,000 people who record themselves as "Hawaiian" alone. This includes folks like my grandmother who is only about 20% Hawaiian. It also goes the other way. There will be folks who are around 75% Hawaiian who will identify as mixed. The reasons why this is so is pretty complex, which includes political and cultural affiliations as well as a rural/urban divide.

A less problematic assignment would have been to use Samoans and mixed Samoans. There's more full bloods to sample from and less mess with self-identification. I have feeling that a better control of Polynesians might have shed some illumination on the chubby factor there.

Next, just as a note, the "Latino" mixes will mostly be Puerto Rican and old school Filipino (pre-1940). Many of the "white" mixes will actually be Portugese and Spanish, more akin to that of ethnic whites in the mainland than "white people". It's no mistake that Northern Europeans and Portugese/Spanish had/have totally different "racial" classifications within the popular consciousness in Hawaii.

Thirdly never underestimate the fatitude of a culture that invented Spam Musubi, Spam Katsu and feeding full meals to even casual guests. I think one of the major problems here is that most people on the mainland think "Race-mixing" and think of the children of "post-racial" professional college grads and not the mass sort of mixing of under-educated plantation workers which was the base of Hawaii's ethnic mixing. In other words, anyone who thinks that mixed-race equals beautiful, healthy, intelligent kids has been sipping the Flavor-Aide. Dumb and ugly people tend to have dumb and ugly kids, no matter what race mixture they are. No big surprise.

Google "behavior genetics" -- genetic differences contribute to differences in IQ and personality traits, the basis for complex (IQ) social behavior (personality).

I'm not interested in wackaloon white supremacist cockamamie bullshit. I'm interested in the scientific evidence Razib seems to be alluding to.

Ha, I didn't realize you were such a fan of wackaloon cockamamie bullshit -- I thought you'd just shift the goalposts, but you went right for Godwin's Law, you corner-cutter.

BTW, IQ tests show that East Asians and Ashkenazi Jews score higher than White gentiles, and that Whites from New England score higher than Whites from the South. That's White supremacy for you.

Are the samples pulled from the American population? With the American diet?

If so, part of the problem could be a mix of genetics and diet. The American diet is way to high in sugar, IMHO. The diet is creating havoc with many aboriginal groups. I suspect that Asian populations would have similar problems with the American diet. Obesity in mixed populations could be the result of the introduction of a fat diet to genes that can't cope as well with it. Culture in the non-mixed non-white groups would protect them from the American diet.

.... just a thought.

Blacks have [...] adopted agriculture only recently

Ummm. What?

By Shambles. (not verified) on 04 Aug 2008 #permalink

"20.5 [BMI], bitches"

thats not something males brag about.

By Turdgood Marshall (not verified) on 05 Aug 2008 #permalink

For instance, the prevalence of overweight/obesity in five ethnic admixtures--Asian/white, Hawaiian/white, Hawaiian/Asian, Latina/white, and Hawaiian/Asian/white ethnic admixtures--was significantly higher than the average of the prevalence estimates for their component ethnic groups.

Further research is needed to determine whether this actually translates into increased health risk for these ethnic admixtures, or, whether 'hybridization might lead both to very low fitness individuals and to very high fitness individuals'. Apparently, BMI (alone) is not an accurate indicator of fatness and obesity because somatotype is not taken into consideration. As an example, many power athletes (e.g., football players, sprinters, weightlifters) are classified as obese because of BMI's above 30; sumo wrestlers likely have the same BMI, but clearly have more adipose tissue than power athletes. So without a somatotype assessment, it's difficult to tell whether the overadditive phenomenon is due to changes in somatotype (e.g., ectomporhic to endomorphic; ectomorphic to mesomorphic).

By Tony Jeremiah (not verified) on 05 Aug 2008 #permalink

Physioprof thinks behavioral genetics is "wackaloon white supremacist cockamamie bullshit".

Hilarious. Where does he teach, a community college?

I have read crosses not resulting in intermedate progeny but a very diverse collection of forms differing markedly both from each other and the parents is considered an indication that the parents are possibly different species.

If a man and woman of different races have a child that child will have deleterious alelles "masked" and may exibit hybrid vigour. Ok, fast forward, the chid is now an adult and gets it on with a mate who is the result of the same racial mix. In this scenario the deleterious alelles are no longer masked and are brought back in combination.
Happy ending?

The answer to the Asian/white thing is simple.. Southeast Asians are much more prone to obesity than East Asians, who are half of the "Asian" category.

Most Asian female/white male pairings are Southeast Asians or those with Southeast Asian genes originating from East Asian nations.

By anonymous (not verified) on 29 Aug 2009 #permalink