Thread: Is it better to be mixed race?

Watched this interesting programme:

http://www.channel4.com/programmes/i...es-1/episode-1

well worth watching. The basic premise of the programme is that being mixed race confers genetic advantage. This genetic advantage is said to be because of an increased heterozygosity in mixed race people, particularly 1st generation.

Has anyone else ever come across this idea?

How much evidence is there to support it?
(If you do watch it: not sure the part looking at mental health robustness in mixed race groups sounded like the best science -be interesting to get the study design/results.)

But the biggest issue it raises, for me at least, is the perpetuation of the idea that race is a real biological category. I've had to study race for my own research up to population genetics were it gets a bit heady for me, but there seems a raging debate among geneticists, population biologists and anthropologists whether race is a biological construct. If not, the hypothesis of mixed race superiority stalls before it even gets off the ground.

I'm not a biologist so it'd be interesting to get some feedback from people more in the loop than myself.

In many animal species researchers have found a negative correlation between internal relatedness and reproductive success. You can find info relating to yearly reproductive success in male brown bears and how it related to internal relatedness (as well as individual age and body mass, as well as the population density) here. The article also references several publications that have found similar results with different animal species.

Basically, within a species, the more heterozygous an individual is the more reproductive success it had on average.

Whether or not races are biological constructs (I do not exactly follow what you mean here?), it is true that someone of a different race as you would be less closely related, and thus having children with someone of another race would likely produce off spring with more heterozygous genes than having children with the same race.

Taking this to the extreme however, crosses between different species, which are often sterile, are a case where large amounts of differences cause greatly reduced viability in the offspring compared to either parent. Lions and tigers are both far more impressive animals when it comes to survival ability than either the miniature tigons or giant ligers.

Race is certainly an artificial construct. Some black people tend to be more closely related, genetically, to some Europeans than other black people. The way we have divided racial groups historically has been on superficially available phenotypes rather than on any significant genetic difference.

That being said, of course someone from Western Europe is likely going to share more genes with someone else from Western Europe.

In general, more heterozygosity is good, but that depends on what genes your getting. *edited out bad example*

Edit: That's a poor example... gah.

Here's a better way to phrase it: I don't think a child of mixed race who inherited a sickle cell gene form African heritage, or a predilection for Celiac disease from a Western European heritage is going to be better off from being mixed race. It's probably true that more times than not the dice will land in favor of a child who's parents are more distantly related from each other.

Diversity is definitely good, but you'd be surprised how close we are despite differences in skin color. You may be more genetically similar to a person who looks your polar opposite than you are to a person who looks almost identical.

I dated a girl with a white father and black mother some years ago. She had MS. Her sister had diabetes. Her other sister was deaf. Another sister was showing signs of some other auto immune disorder.

We can't generalize. Genetic variation tends to be good when the environment and circumstance changes. However, we must look at it on a case by case basis.

Originally Posted by inow

We can't generalize. .

we can generalise, we frequently generalise, we generalise both collequally and scientifically. We could not learn without some recourse to generalisation

OK so I am being picky

Now you can generalise about me!

Fair enough. "On this topic" as well as in others we must be "cautious" when we generalize as it can "easily lead to" inaccuracies and misunderstandings.

Please note, the above is a generalization. This product may cause birth defects and should not be used by pregnant women. Be sure not to swim within 30 minutes of eating. All creationists ate paste when they were kids.

As the saying goes, all generalizations are false.

As far as the original question is concerned, I see no reason to think human genetics would be any different than other animals. Cross-breeding can result in either desirable traits (hybrid vigor)
http://en.wikipedia.org/wiki/Heterosis
or undesirable traits (outbreeding depression)
http://en.wikipedia.org/wiki/Outbreeding_depression

Of course, the desirability or undesirability of a trait can be subjective as well.

Originally Posted by C.Elrod

Whether or not races are biological constructs (I do not exactly follow what you mean here?),

The idea is that populations are biologically sufficiently different to consider them distinct groups; called races. It has roots Linnaeus’s classifications but really took off in the 19th century.
I've come to the same conclusion as i_feel_tiredsleepy; it's a constuctivist fallacy. I base this on the idea that by definition a sub-species requires allelle variation Fst = 0.25-.030 whereas human allelle variation between races is Fst = 0.156. Still many people support the idea that populations can be divided based on biology/genetics.

It'd be interesting to see if they measured allelle variations in the article you provide but the link's not working for me.

I guess my question is do the putative advantages of being mixed 'race' mean there exists a biological/genetic construct 'race'?

I suspect race could be used as a proxy measure for genetic variation in leiu of direct DNA testing - which is why race is still used in biomedical research and pharmaceuticals have actually made 'race' specific drugs.

Originally Posted by Prometheus

I've come to the same conclusion as i_feel_tiredsleepy; it's a constuctivist fallacy. I base this on the idea that by definition a sub-species requires allelle variation Fst = 0.25-.030 whereas human allelle variation between races is Fst = 0.156. Still many people support the idea that populations can be divided based on biology/genetics.

What do you suppose would be the allele variation between a Siberian Husky and a Chihauhua dog?

Originally Posted by inow

…Be sure not to swim within 30 minutes of eating.

Do not go in the water until you've learned to swim.


Marry someone well beyond your cousins.

Originally Posted by Harold14370

Originally Posted by Prometheus

I've come to the same conclusion as i_feel_tiredsleepy; it's a constuctivist fallacy. I base this on the idea that by definition a sub-species requires allelle variation Fst = 0.25-.030 whereas human allelle variation between races is Fst = 0.156. Still many people support the idea that populations can be divided based on biology/genetics.

What do you suppose would be the allele variation between a Siberian Husky and a Chihauhua dog?

I've no idea, but i suspect the variation will be smaller than the criterion set above, still leading to large differences in phenotype between these two breeds.

But before you tell me let me ask, is it sufficient to seperate a human population based on its phenotype and say this distinction has a bioligocal basis?

For instance, it is obvious that a white and a black person have differences in the phenotype of skin colour. But This will not be the only phenotypic variation between these 2 individulas - how certain drugs are metabolised may also vary. Just because the former is more obvious it has become a biological marker for 'race', but why not the latter? There are so many phenotypic variations between individuals and populations that we could choose hundreds of ways with which to demarcate 'races'. But we don't, we have selected those we have deemed important, skin colour among some others, and divided populations accordingly. The choice of phenotypes to make this distinction was arbitary - therefore i see 'race' as a social, not biological constuct.

Originally Posted by Prometheus

The choice of phenotypes to make this distinction was arbitary - therefore i see 'race' as a social, not biological constuct.

So do most biologists.


http://en.wikipedia.org/wiki/Race_%2...n_of_humans%29

Racial groupings may correspond with patterns of social stratification, helping social scientists to understand the underlying disparities among racially defined groups of people.[4] Additionally, law enforcement utilizes race to create profiles of wanted suspects in an expeditious manner.

While scientists use the concept of race to make practical distinctions among fuzzy sets of traits, the scientific community feels that the idea of race is often used by the general public[5] in a naïve[6] or simplistic way, erroneously designating wholly discrete types of individuals. Among humans, race has no cladistic significance—all people belong to the same hominid subspecies, Homo sapiens sapiens.[7][8] Regardless of the extent to which race exists, the word "race" is problematic and may carry negative connotations.[9] Social conceptions and groupings of races vary over time, involving folk taxonomies[10][11][12] that define essential types of individuals based on perceived sets of traits. Scientists consider biological essentialism obsolete,[13] and generally discourage racial explanations for collective differentiation in both physical and behavioral traits.[6][14]

As people define and disseminate different conceptions of race, they actively create contrasting social realities through which racial categorization is achieved in varied ways.[15] In this sense, races are said to be social constructs.[16][17] These constructs can develop within various legal,[15][18] economic,[18] and sociopolitical[19][20] contexts, and at times may be the effect, rather than the cause, of major social situations.[19]

<...>

In biology the term "race" is used with caution because it can be ambiguous, "'Race' is not being defined or used consistently; its referents are varied and shift depending on context. The term is often used colloquially to refer to a range of human groupings. Religious, cultural, social, national, ethnic, linguistic, genetic, geographical and anatomical groups have been and sometimes still are called 'races'".[7] Generally when it is used it is synonymous with subspecies.[41] One main obstacle to identifying subspecies is that, while it is a recognised taxonomic term, it has no precise definition.[42]

<...>

Most modern anthropologists and biologists came to view race as an invalid genetic or biological designation.[53]

The first to challenge the concept of race on empirical grounds were anthropologists Franz Boas, who demonstrated phenotypic plasticity due to environmental factors,[54] and Ashley Montagu who relied on evidence from genetics.[55] E. O. Wilson then challenged the concept from the perspective of general animal systematics, and further rejected the claim that "races" were equivalent to "subspecies".[56]

<...>

One result of debates over the meaning and validity of the concept of race is that the current literature across different disciplines regarding human variation lacks consensus, though within some fields, such as biology, there is strong consensus.

Please note how well referenced the parts I shared are. This is not based on some single individual crusade to rid the world of distinction. Race is truly a term rejected in biology due to the many ways it is found lacking, inaccurate, and without utility.

Originally Posted by Prometheus

But before you tell me let me ask, is it sufficient to seperate a human population based on its phenotype and say this distinction has a bioligocal basis?

Is a difference in phenotype biological? I would say, yes. Probably.

If you are "white" race with O negative blood and get in an accident, its better to get AB+ blood from someone of your own "Race" than O negative blood from someone of the "black" race. :-D

Also to be safer, you should travel from village to village, starting from Ireland going through northern europe down to mid and southern europe, then move counter clockwise around the Mediterranean Sea with a detour to iran,pakistan and india and back to africa and travel deep into the continent, using a paint palette chart like this:

this way you will be able to draw a line in the sand on a map of the world and on the tan palette chart to determine which particular skin tone you select as the threshold basis to seperate the races.
... You should draw the line at ~Wilmington Tan~, and that would be the correct delimitation, unlike the fools who are wrong at setting it to ~Richmond Gold~ which is obvioulsy scientific heresy or the purists that draw the line at ~Hepplewhite Ivory~ which was not peer reviewed by the Academy of Racists Scholars and thus invalid.

But kidding asside diversity is better generally speaking imo, though the outward appearance is just one factor, other factors that arent visible (ex:T-cell wall configuration) can mean the difference between life or death is certain situations within people who outwardly look very similar. I would simply avoid closely related mates and use the many other relationship-related characteristics, and also note that the environement plays a part in many issues. Having white color in a butterfly can be perceived as a defect, but if the landscape changes to white it becomes advantageous, for all we know there might be a defect(difference) that has no symptoms or causes some humans to experience fatigue when running after drinking melon juice that also happens to protect the person from a nanoparticle contaminate or deadly pandemic in an hypothetical future. :wink:

Originally Posted by Harold14370

Is a difference in phenotype biological? I would say, yes. Probably.

A difference in phenotype might be biological, but it does not follow that race is biological. Height is a phenotypic variation but we do not distinguish people of different heights and say the difference is due to them belonging to a certain 'height' group.

Icewendigo's blood groups are an example of this. Blood groups vary by 'race'. This is a statistically inference - you are more likely to find a match from 2 two people from the same 'race' - but not necessarily so. You have to test a person's antibody status before giving them blood, you can't just assume because they are the same race they are compatible, you'd get loads of transfusion reactions. This is further compounded by the fact there are about 30 blood systems to measure for in transfusions (By the way Icewendigo, if you gave AB+ blood to an O- patient you'd get a haemolytic reaction regardless of race, so your example is wrong i'm afraid).

I like the palette chart, it raises another criticism of race as a biological construct: it may be easy to differentiate an African from a Mongoloid, but in between is every mix so where do we draw a line? This, apparently, is not due to recent admixture but that homo sapiens are too young for significant genetic drift.

However, there are still plenty of people who use it, medicine and pharmacology mainly as well as geneticists. This article explains it better than i: http://www.sciencemag.org/content/298/5597/1337.full

Originally Posted by Prometheus

Originally Posted by Harold14370

Is a difference in phenotype biological? I would say, yes. Probably.

A difference in phenotype might be biological, but it does not follow that race is biological. Height is a phenotypic variation but we do not distinguish people of different heights and say the difference is due to them belonging to a certain 'height' group.

Well, race has to do with a collection of phenotypes, so yes it does follow that race is biological. What else do you think it is? We certainly can distinguish people by height, if we have a reason to do so. Maybe we are putting together a basketball team. Also, there are names for groups of people, like giants or dwarves, that are based on height.

I like the palette chart, it raises another criticism of race as a biological construct: it may be easy to differentiate an African from a Mongoloid, but in between is every mix so where do we draw a line?

Biologists who classify plants and animals sometimes have a hard time deciding if a particular population is a subspecies, a separate species, or part of another species. That does not mean that they have to abandon the whole idea of classifying plants and animals.

This, apparently, is not due to recent admixture but that homo sapiens are too young for significant genetic drift.

The genetic drift is significant enough that we can often look at a person and easily tell the general part of the world his ancestors came from. What you do with that information is up to you, however it is silly to suggest that the differences don't exist.

I understand. Race is a sensitive topic. People don't want to be accused of being racist, so they try to be as politically correct as possible. However, that approach often leads to them taking a nonsensical position.

You have already admitted that race can be useful in medicine, so I don't know why you are even arguing the position.

Originally Posted by Harold14370

Well, race has to do with a collection of phenotypes, so yes it does follow that race is biological.

Ah, but this is the point. The collection of phenotypes that differentiate race are arbitrary and selected by us. It might appear obvious to us that white and black pigmentation makes for a different category of people. This does not necessarily mean it is a biological reality because given the many phenotypes resulting from our genotype there must be millions of ways in which we could divide populations, and those divisions would never quite be the same. This is why i say it is a social category - because we have pre-selected the few phenotypes we have deemed most important without knowing of the rest.

Originally Posted by Harold14370

The genetic drift is significant enough that we can often look at a person and easily tell the general part of the world his ancestors came from. What you do with that information is up to you, however it is silly to suggest that the differences don't exist.

The point is not whether differences exist, but whether differences are significant enough to say different populations exist. I guess a lot depends on where we choose to say 'significant' lies. As i_feel_tiredsleepy pointed out, it is possible for an African to be more genetically similar to a European than an other African. Racial groupings are just too heterogeneous.

Originally Posted by Harold14370

You have already admitted that race can be useful in medicine, so I don't know why you are even arguing the position.

The question is not whether 'race' is useful but whether it is a social or biological construct. It's only useful in medicine as a proxy for certain risk factors (e.g. indian sub-continent and diabetes m.); but it can't be used isolation. Once genetic profiling becomes widely available race will be irrelevant in a health context, as genetic risk factors would be directly measured.

Originally Posted by Prometheus

Originally Posted by Harold14370

The genetic drift is significant enough that we can often look at a person and easily tell the general part of the world his ancestors came from. What you do with that information is up to you, however it is silly to suggest that the differences don't exist.

The point is not whether differences exist, but whether differences are significant enough to say different populations exist. I guess a lot depends on where we choose to say 'significant' lies. As i_feel_tiredsleepy pointed out, it is possible for an African to be more genetically similar to a European than an other African. Racial groupings are just too heterogeneous.

That, and estimating peoples' ancestry from how they look is much less reliable than most people believe.

Originally Posted by Harold14370

Biologists who classify plants and animals sometimes have a hard time deciding if a particular population is a subspecies, a separate species, or part of another species. That does not mean that they have to abandon the whole idea of classifying plants and animals.

The point is that race has been demonstrated over and over and over yet again to be a fairly useless classifier. I thought this had been established in my previous post. :?

Originally Posted by Harold14370

I understand. Race is a sensitive topic. People don't want to be accused of being racist, so they try to be as politically correct as possible. However, that approach often leads to them taking a nonsensical position.

Again, why are you ignoring the data shared in this very thread?

Originally Posted by inow

The point is that race has been demonstrated over and over and over yet again to be a fairly useless classifier. I thought this had been established in my previous post. :?

Fairly useless? Maybe. So what? The article you quoted also said "scientists use the concept of race to make practical distinctions among fuzzy sets of traits." You also seem to be ignoring the use in medicine, which has been previously mentioned.

The only reason I jumped in was because people are making arguments that do not make logical sense. For example, the idea that variations are not "significant" unless they rise to the level of being a subspecies. If that were true, evolution could never occur, because each incremental change is not "significant." Or the idea that we cannot make clssifications unless each member of the class fits unambiguously into its own class. I guess you think I should let dumb arguments go by without comment because you have made the be-all and end-all post about race.

Originally Posted by Twit of wit

That, and estimating peoples' ancestry from how they look is much less reliable than most people believe.

We are not most people.

The only difference between a mouse and a human is a mouse has a genome sequence we don't have and a human has a sequence that the mouse does not have but all other genes are identical.

There is a big difference between the appearance of a mouse and a human but at the genetic level there is basically little differences.

Originally Posted by Harold14370

Originally Posted by Twit of wit

That, and estimating peoples' ancestry from how they look is much less reliable than most people believe.

We are not most people.

You are.

Originally Posted by Harold14370

For example, the idea that variations are not "significant" unless they rise to the level of being a subspecies. If that were true, evolution could never occur, because each incremental change is not "significant." Or the idea that we cannot make clssifications unless each member of the class fits unambiguously into its own class.

I never made a single argument even remotely resembling that. What is your point? You appear no longer to be speaking about the concept of race (which is specifically what I commented on), and you appear not to be replying to me, but instead to some caricature you have in your head.

Originally Posted by inow

I never made a single argument even remotely resembling that. What is your point? You appear no longer to be speaking about the concept of race (which is specifically what I commented on), and you appear not to be replying to me, but instead to some caricature you have in your head.

Well, you obviously haven't been paying atttention to anything that's been posted on this thread. I posted in response to someone else, then you attacked me for it. You should have at least read the posts I was responding to.

Originally Posted by Harold14370

Well, you obviously haven't been paying atttention to anything that's been posted on this thread. I posted in response to someone else, then you attacked me for it. You should have at least read the posts I was responding to.

Okay. I suppose you're somewhat sensitive to attack. Didn't realize your personal character was being challenged when I said:

Originally Posted by inow

The point is that race has been demonstrated over and over and over yet again to be a fairly useless classifier. I thought this had been established

Originally Posted by inow

Originally Posted by Harold14370

Well, you obviously haven't been paying atttention to anything that's been posted on this thread. I posted in response to someone else, then you attacked me for it. You should have at least read the posts I was responding to.

Okay. I suppose you're somewhat sensitive to attack. Didn't realize your personal character was being challenged when I said:

Originally Posted by inow

The point is that race has been demonstrated over and over and over yet again to be a fairly useless classifier. I thought this had been established

By addressing that to me, you are implying that I didn't get the message, and that I am stubbornly refusing to acknowledge your thread-ending Wikipedia post on the subject, which by the way does not say exactly what you seem to think it says. That was not the case at all. I was arguing against a fallacious line of argument. You cannot dismiss race as a classification simply because there are gray areas. There are gray areas in all classifications.

There are problems with the effectiveness of race as a measure in medicine. Primarily, the main problem is that most black people being tested in the US have long been part of the same breeding population in the Southern USA, and before that they largely came from the same regions of Africa. So, the effectiveness of race as a predictor is not universal, if you wanted to use race as a predictor for a sample of people taking from all over Africa, it would likely fall apart.

Originally Posted by Harold14370

You cannot dismiss race as a classification simply because there are gray areas. There are gray areas in all classifications.

Not because there are gray areas, but because there are mostly gray areas.
The second thing you don't get is that what people call "races" is not based on actuall genetic difference but on few visible traits. The distribution of other traits is entirely different, for example blood types:
http://anthro.palomar.edu/vary/vary_3.htm

Originally Posted by Twit of wit

Not because there are gray areas, but because there are mostly gray areas.

This is a different argument than the one I was refuting.

The second thing you don't get is that what people call "races" is not based on actuall genetic difference but on few visible traits. The distribution of other traits is entirely different, for example blood types:
http://anthro.palomar.edu/vary/vary_3.htm

What is it that you think I don't get? I made no claims about blood type or any other specific non-visible traits. What you have written here makes no sense, because the "few visible traits" are caused by "actual genetic differences." What else could account for a difference in the visible traits if it is not genetic. A suntan, maybe?

Genetic differences alone do not make for racial categories: i'm genetically different from my brother but not a different race. So what other criteria in addition to genetic difference would you add to qualify race?

I assume you mean clusters of genetic traits found in ancestral continental groups?

This article form the New England Journal of Medicine explains why this does not work. It also explains the use of race in medicine.
http://www.nejm.org/doi/full/10.1056/NEJMsb022863 (need to register to see the full text)

To paraphrase the article (coz science still isn't free for all):Though skin colour varies systematically it does not follow that racial categories are an effective way of classifying populations. This is exacerbated by confusing 'race' as a scientific term when, in genetic terms, there is no quantifiable definition of race.

Originally Posted by Harold14370

We certainly can distinguish people by height, if we have a reason to do so.

Yes we can, and as you say these people will be genetically different, but we don't say basketball teams are therefore a different race of people.

Originally Posted by Harold14370

For example, the idea that variations are not "significant" unless they rise to the level of being a subspecies. If that were true, evolution could never occur, because each incremental change is not "significant."

This is a misunderstanding of what we mean by significant. It is a property of mind not phenomena, and is a relative term. We choose what is significant. Am i significantly genetically different from my brother? Depends on what we choose to be 'significant', not an inherent difference between us.

Maybe this is really where our different opinions lie; how we define race and how we draw a line between populations.

Originally Posted by inow

Originally Posted by Harold14370

Biologists who classify plants and animals sometimes have a hard time deciding if a particular population is a subspecies, a separate species, or part of another species. That does not mean that they have to abandon the whole idea of classifying plants and animals.

The point is that race has been demonstrated over and over and over yet again to be a fairly useless classifier. I thought this had been established in my previous post. :?

I think the uselessness is a good point to consider. It's not that it's not a use-able classifier, right? It's just not informative. I can work with that explanation. I wouldn't be convinced that there is no use in categorizing human populations, however. Just not using simple markers like skin color.

A white viking from Scandanavia is likely to be taller than a white Visgoth from Spain. An Eskimo from Northern Alaska will have greater ability to handle the cold than someone of Aztec descent from Mexico. And, you really can't ignore the tendency of certain subgroups of black people to be able to dunk over most subgroups of white people in the game of basketball.

Originally Posted by Harold14370

I understand. Race is a sensitive topic. People don't want to be accused of being racist, so they try to be as politically correct as possible. However, that approach often leads to them taking a nonsensical position.

Again, why are you ignoring the data shared in this very thread?

I kind of agree with Harold. I think the fear of Nazis is making biologists behave much more cautiously than scientist in other fields behave. Morally, that might be a good thing, but scientifically I doubt this serves to improve our collective understanding of the topic.

Originally Posted by Prometheus

Genetic differences alone do not make for racial categories: i'm genetically different from my brother but not a different race. So what other criteria in addition to genetic difference would you add to qualify race?

I assume you mean clusters of genetic traits found in ancestral continental groups?

In the context of the original post on this thread, I think you could use such clusters of traits to choose a mate with whom you shared fewer genes, on average, than a randomly chosen mate, or a mate of your own race. Not that I think there would be any advantage in doing so, as I stated already.

Originally Posted by Harold14370

We certainly can distinguish people by height, if we have a reason to do so.

Yes we can, and as you say these people will be genetically different, but we don't say basketball teams are therefore a different race of people.

I didn't say it would be a different race, only that we could classify people by height. Besides that, height is one characteristic that has been used to classify racial groups. Pygmies, for example.

Am i significantly genetically different from my brother? Depends on what we choose to be 'significant', not an inherent difference between us.

Maybe this is really where our different opinions lie; how we define race and how we draw a line between populations.

The original thread topic was about selective breeding of people. In that context, you could well be significantly different than your brother. Selective breeding is accomplished by selecting individuals, possibly among brothers or sisters from the same litter, which have a desired trait. That's just ordinary barnyard common sense that farmers, plant breeders, and animal breeders have known about for tens of thousands of years.

I am no kind of biologist, but I think people are no different than any other animals, so why shouldn't they be classified the same way?
Suppose an ornithologist notices that the northern shitwhistler has longer tailfeathers than the southern shitwhistler, and an orange bill instead of red. Then he might decided to put them in a different class of shitwhistlers. The other ornithologists might disagree whether there are two subspecies of shitwhistlers. I don't think they would get on their high horse and complain about the popular misconceptions that the general public have about shitwhistlers, nor would they feel obliged to point out that all shitwhistlers have the same blood type.

Originally Posted by Harold14370

In the context of the original post on this thread, I think you could use such clusters of traits to choose a mate with whom you shared fewer genes, on average, than a randomly chosen mate,

And, has been established already earlier in this thread, the melanin content in a human persons skin does not provide the information you think it does. The genes of two people of completely different skin colors can be MUCH more similar than the genes of two people sharing the same dermal tone.

If you agree, then awesome... I'm just reinforcing the point. If you disagree, then you're wrong.

Originally Posted by inow

Originally Posted by Harold14370

In the context of the original post on this thread, I think you could use such clusters of traits to choose a mate with whom you shared fewer genes, on average, than a randomly chosen mate,

And, has been established already earlier in this thread, the melanin content in a human persons skin does not provide the information you think it does. The genes of two people of completely different skin colors can be MUCH more similar than the genes of two people sharing the same dermal tone.

If you agree, then awesome... I'm just reinforcing the point. If you disagree, then you're wrong.

The key phrase here is "can be." I am talking about probabilities given the available information. It is a fact that people who are closely related tend to have a family resemblance. Of course, you could look more like somebody else than a member of your own family. Odds are against it.

This is how doctors can decided to test a person with dark colored skin for sickle cell anemia, but may look for some other cause of the problem if a person is white. A white person could have it. Probably not.

Harold,
the point you still seem to be missing and the one I believe I-now is making is this:

The genetic variations responsible for 'racial' differences are a small subset of the total range of genetic differences. Most genetic differences do not correlate with this small subset of 'racial' identifiers. Thus 'race' is pretty well irrelevant, or ought to be. I don't go around saying "Some of my best friends have AB+ blood."

You seem to be assigning some almost mystical significance to superficial characteristics. If I'm reading you wrong I'm sure you will correct me.

Originally Posted by Harold14370

Originally Posted by Prometheus

Genetic differences alone do not make for racial categories: i'm genetically different from my brother but not a different race. So what other criteria in addition to genetic difference would you add to qualify race?

I assume you mean clusters of genetic traits found in ancestral continental groups?

In the context of the original post on this thread, I think you could use such clusters of traits to choose a mate with whom you shared fewer genes, on average, than a randomly chosen mate, or a mate of your own race. Not that I think there would be any advantage in doing so, as I stated already.

We are beginning to agree. You could use race for mate selection the same way doctors use use it: as a proxy marker (known as the 'poor man's clue' in medical literature). Not sure about the advantages of being mixed race, hence starting the thread, but i do know mixed race women are the most beautiful.

Originally Posted by Harold14370

I am no kind of biologist, but I think people are no different than any other animals, so why shouldn't they be classified the same way?
Suppose an ornithologist notices that the northern shitwhistler has longer tailfeathers than the southern shitwhistler, and an orange bill instead of red. Then he might decided to put them in a different class of shitwhistlers. The other ornithologists might disagree whether there are two subspecies of shitwhistlers. I don't think they would get on their high horse and complain about the popular misconceptions that the general public have about shitwhistlers, nor would they feel obliged to point out that all shitwhistlers have the same blood type.

And such an argument would largely be around taxonomy, not biology. There are two reasons why people get on high-horses regarding race: the previously mentioned sensitivity borne from the unsavoury roots of racial science and the fact scientists need to define their variables to a degree which appears arbitrary to lay people (very hard with such a loose concept as race).

Originally Posted by Harold14370

This is how doctors can decided to test a person with dark colored skin for sickle cell anemia, but may look for some other cause of the problem if a person is white. A white person could have it. Probably not.

When genetic profiling becomes widely available doctors won't need to use race at all.

Originally Posted by Prometheus

Originally Posted by C.Elrod

Whether or not races are biological constructs (I do not exactly follow what you mean here?),

The idea is that populations are biologically sufficiently different to consider them distinct groups; called races. It has roots Linnaeus’s classifications but really took off in the 19th century.
I've come to the same conclusion as i_feel_tiredsleepy; it's a constuctivist fallacy. I base this on the idea that by definition a sub-species requires allelle variation Fst = 0.25-.030 whereas human allelle variation between races is Fst = 0.156. Still many people support the idea that populations can be divided based on biology/genetics.

In the video you linked to they claimed that this is the case-that the mixed person (low sample size of mixed people...) was much more heterozygous than everyone from a larger sample size of "non-mixed" (as in European, Indian, Native American, etc) people.
They also claimed that people of different ethnic origins are vulnerable to different diseases. This could very well be culturally related though (particularly diet, but other environmental factors could be the cause as well).
If it is true that Europeans are naturally more prone to dementia, and another group is more prone to heart disease, a hybrid would then on average likely be resistant to both-one working gene is all that should be necessary for the most part.
I would however expect that there is also a good bit of variation within each population in these areas, but on average I would expect the difference to be greater between two members of different populations than between two members of the same population.

Originally Posted by Prometheus

It'd be interesting to see if they measured allelle variations in the article you provide but the link's not working for me.

Odd. The article title is "Genetic Estimates of Annual Reproductive Success in male brown bears: the effects of body size, age, internal relatedness and population density", if that can perhaps help you access it.
The link works for me-I assume you have some program that can open .pdfs?

Here is how internal relatedness was calculated:
Internal relatedness = (2H-Σffi)/(2N - Σfi)
H=the number of homozygous loci
fi=frequency of ith allele in gentotype
N= number of loci genotyped

Here is some info from the discussion section:
Internal relatedness was correlated negatively with reproductive success. The article quotes a large number of other studies that have found similar results. Some speculation occurred as to the mechanisms, and similar results in some other species and studies were cited.

Almost all of the references above look like they could provide a lot of information on this subject if you wish to explore further. The title of the references listed above are:
David '98: Heterozygosity-fitness correlations: new perspectives on old problems
Brown '97: A theory of mate choice based on heterozygosity
Bellemain et al 2006: The dilemma of female mate selection in the brown bear, a species with sexually selected infanticide
Amos 2001: Do female gray seals select genetically diverse males?
Slate et al 2000: Inbreeding depression influences lifetime breeding success in a population of wild deer (Cervus elaphus)
Anderson 1994: Sexual Selection

Originally Posted by Prometheus

I guess my question is do the putative advantages of being mixed 'race' mean there exists a biological/genetic construct 'race'?

I don't think a mixed advantage necessitates that race is a real biological construct. As I explained earlier, I think a mixed race advantage would simply be a result of somewhat greater heterozygosity a child whose parents came from different parts of the planet would likely have on average.

One clear example would be getting a single copy of the sickle cell gene-with only the potential to get one copy, they will not be able to suffer from the disease (as one must be homozygous), but one copy (heterozygosity) does provide the benefit of increased resistance to malaria.
This is the case for a large variety of much more minor genetic diseases (that often provide more minor benefits to immune resistances, such as resistance to more minor threats, or less resistance to such major threats as malaria).

Originally Posted by Prometheus

I suspect race could be used as a proxy measure for genetic variation in leiu of direct DNA testing - which is why race is still used in biomedical research and pharmaceuticals have actually made 'race' specific drugs.

I agree-genetic differences do seem clear, but calling them real separate constructs would be a fallacy.

A far more extreme example would be ring species, where two different species fade into each other, where the ends cannot interbreed, but they are connected by a ring of species all capable of interbreeding with one another-my point is that I disagree with any strong labeling of one thing as entirely separate and distinct from another.
Unlike the ring species, humans are most obviously a single sub species (let alone separate species); we evidently as a species have much less genetic diversity than chimps.

I would err on the side of caution when quoting large blocks of text from papers. Even when they're open access, that doesn't necessarily mean it's legally okay to reproduce the text without permission. Even when writing papers we rarely quote even small pieces of other papers. NEJM is not an OA journal, so I'd be a bit worried about the excerpts above. Could you perhaps summarize the content and remove the quoted text?

Originally Posted by TheBiologista

I would err on the side of caution when quoting large blocks of text from papers. Even when they're open access, that doesn't necessarily mean it's legally okay to reproduce the text without permission. Even when writing papers we rarely quote even small pieces of other papers. NEJM is not an OA journal, so I'd be a bit worried about the excerpts above. Could you perhaps summarize the content and remove the quoted text?

By quoting I am at least giving full credit for the work to the authors, but I understand plagiarism isn't the concern here.
I removed the quoted text.

I can access the article now C.Elrod, thanks. Interesting that they suggest female bears may select for heterozygosity. I wonder if the same thing occurs in humans? Seems like we're more likely to breed with people of the same culture - usually more homozygous. Is this a case of the putative meme versus genetic selection? And i wonder if anyone will ever investigate this properly in humans given the sensitivities around race.

Interesting about ring species - i had not come across this concept before...

Originally Posted by Prometheus

Interesting that they suggest female bears may select for heterozygosity.

Can't believe bears would assign almost mystical significance to superficial characteristics.

I would like to know how they choose.

Originally Posted by Harold14370

Originally Posted by Prometheus

Interesting that they suggest female bears may select for heterozygosity.

Can't believe bears would assign almost mystical significance to superficial characteristics.

quite surprised you are equating your intellect with that of a bear.

Originally Posted by Ophiolite

Originally Posted by Harold14370

Originally Posted by Prometheus

Interesting that they suggest female bears may select for heterozygosity.

Can't believe bears would assign almost mystical significance to superficial characteristics.

quite surprised you are equating your intellect with that of a bear.

I'm sure a bear is much smarter than I am when it comes to picking a mate for a bear. Their instincts are guided by many years of evolution. Apparently they use superficial characteristics to do so. What's your point?

Originally Posted by Harold14370

I'm sure a bear is much smarter than I am when it comes to picking a mate for a bear. Their instincts are guided by many years of evolution. Apparently they use superficial characteristics to do so. What's your point?

I very much doubt they use superficial characteristics. They would choose characteristics that suggest a healthy animal well capable of supporting itself and passing on 'good' genes to its offspring. They are going for how glossy the coat is, not what colour it is.

Originally Posted by Ophiolite

Originally Posted by Harold14370

I'm sure a bear is much smarter than I am when it comes to picking a mate for a bear. Their instincts are guided by many years of evolution. Apparently they use superficial characteristics to do so. What's your point?

I very much doubt they use superficial characteristics. They would choose characteristics that suggest a healthy animal well capable of supporting itself and passing on 'good' genes to its offspring. They are going for how glossy the coat is, not what colour it is.

1. Glossiness of a coat is superficial. 2. Color of a bear could affect its survival abiliity. 3. The article was about whether bears select for heterozygosity, not a glossy coat.

Originally Posted by Harold14370

Originally Posted by Ophiolite

Originally Posted by Harold14370

I'm sure a bear is much smarter than I am when it comes to picking a mate for a bear. Their instincts are guided by many years of evolution. Apparently they use superficial characteristics to do so. What's your point?

I very much doubt they use superficial characteristics. They would choose characteristics that suggest a healthy animal well capable of supporting itself and passing on 'good' genes to its offspring. They are going for how glossy the coat is, not what colour it is.

1. Glossiness of a coat is superficial. 2. Color of a bear could affect its survival abiliity. 3. The article was about whether bears select for heterozygosity, not a glossy coat.

I read an article about how the white colored black bears are more vulnerable to being killed due to lack of camouflage in most of their environment, but how they achieve larger average weights than the actually black bears due to much better camouflage when trying to fish in the water; normal black bears are much better at fishing at night, while the white colored bears are equally successful regardless of time of day, making them better at obtaining food in areas where fish make up an important part of their diet.
This is an extreme difference, but it definitely is.

That the trait isn't entirely superficial must be evident by the ability of female bears to select for it at all.

Traits like glossy coats in most mammals, dark colored manes in lions, and color of a peacocks feathers are all health indicators.
The darker a male lion's mane the more it sticks out when trying to ambush a prey animal, yet females select for dark maned lions because these lions have higher testosterone levels and are overall healthier, and more physically fit animals (leading to the instinctive assumption by females that they must be fitter in a Darwinian sense as well).

More heterozygosity could provide an especially great advantage when it comes to the immune system; through getting sick less and being burdened with lower loads of parasites and disease a more heterozygous bear would likely look healthier and be larger-assuming the correlation between heterozygosity and disease resistance is fairly strong.
Well fed bears in captivity reach much larger weights than bears of their respective populations do in the wild-I don't only mean fat, but body length and head (skull) size; the limiting factor of the size of wild bears is net calories they can take in when it comes to size.

Originally Posted by Prometheus

I would like to know how they choose.

I would as well; I wish these studies focused more on this.
I would like to eventually start reading through those articles I listed, as they may provide a clue. Above I was merely speculating wildly.

Also, this isn't anything unique to bears. The article referenced Amos et al 2001 suggesting that grey seals also selected for more genetically diverse mates.
It referenced Slate et al 2000 as finding that life time breeding success in both male and female red deer was positively correlated with heterozygosity.

Originally Posted by C.Elrod

That the trait isn't entirely superficial must be evident by the ability of female bears to select for it at all.

The literal definition of "superficial" is "on the surface." By that definition, the color and texture of a bear's fur are superficial, whether or not signficant to its survival.

Originally Posted by Prometheus

I would like to know how they choose.

I would as well; I wish these studies focused more on this.
I would like to eventually start reading through those articles I listed, as they may provide a clue. Above I was merely speculating wildly.

Here is an article about the seals. Apparently nobody really knows how they do it.
http://www.abc.net.au/science/news/s...07/1842870.htm

Still unclear, though, is how female seals are able to spot a partner whose genes are diverse.

They may get visual cues, from the male's body size and condition, his dominant behaviour or the quality of the territory he occupies; or, perhaps, they use smell to see if they are related to him.

Originally Posted by Harold14370

Originally Posted by C.Elrod

That the trait isn't entirely superficial must be evident by the ability of female bears to select for it at all.

The literal definition of "superficial" is "on the surface." By that definition, the color and texture of a bear's fur are superficial, whether or not signficant to its survival.

Okay, I grossly misunderstood the meaning of the statement then. Thanks for the correction.

Originally Posted by Harold14370

Here is an article about the seals. Apparently nobody really knows how they do it.
http://www.abc.net.au/science/news/s...07/1842870.htm

Still unclear, though, is how female seals are able to spot a partner whose genes are diverse.

They may get visual cues, from the male's body size and condition, his dominant behaviour or the quality of the territory he occupies; or, perhaps, they use smell to see if they are related to him.

If more outbred males have better body size and condition, are more dominant, and/or have higher quality territories this would be highly suggestive of there being some benefits, and also suggest that the females do not intend to select for more outbred individuals-that this is merely a consequence of a negative correlation between fitness and internal relatedness.

I once came across a study that suggested humans select for diversity by scent. They thought scents were correlated to immune function so selecting someone of a different scent would maximise diversity of the immune system. Can't remember the study though - anyone else come across it?

Originally Posted by Prometheus

I once came across a study that suggested humans select for diversity by scent. They thought scents were correlated to immune function so selecting someone of a different scent would maximise diversity of the immune system. Can't remember the study though - anyone else come across it?

There are many studies you could mean. One which always fascinated me is how we can tell, by scent alone, how bilaterally symmetric another human is. The similarity or symmetry of their sides is an indicator of good genes and health, and apparently we tend to prefer the scent of those who are more symmetric over those who are not.

The scent of symmetry, it was called. Pretty cool.

http://www.ceacb.ucl.ac.uk/culturecl..._Thornhill.pdf

The first study to indicate that chemical signals play a role in attraction was conducted by Claud Wedekind over a decade ago. Forty-four men wore the same T-shirt for three days. They refrained from deodorants and scented soaps so they wouldn’t interfere with their natural smell. Women then sniffed the shirts and indicated which ones smelled the best to them. By comparing the DNA of the women and men, the researchers found that women didn’t just choose their favorite scent randomly. They preferred the scent of man whose major histocompatibility complex (MHC) -- a series of genes involved in our immune system -- was most different from their own.

From here.

Originally Posted by C.Elrod

Originally Posted by Harold14370

Originally Posted by C.Elrod

That the trait isn't entirely superficial must be evident by the ability of female bears to select for it at all.

The literal definition of "superficial" is "on the surface." By that definition, the color and texture of a bear's fur are superficial, whether or not signficant to its survival.

Okay, I grossly misunderstood the meaning of the statement then. Thanks for the correction.

One of the definitions of superficial is 'insubstantial or insignificant' so it's easy to see how that would be confused.

Thanks for the links guys,

In the documentary they allude to facial symmetry being higher in mixed race people but i'm not sure what study they base this on.

If we are to accept these findings then the question becomes whether race is a good measure of an individual's histocompatibilty complex.

Originally Posted by Prometheus

In the documentary they allude to facial symmetry being higher in mixed race people but i'm not sure what study they base this on.

There have been a few studies like this. I know of one in 2002, and another in 2008, and presume there are a number of others.

You can probably google (or even google scholar) the term "bilateral symmetry mixed race" and find some more info.