Genetic Superiority

[chris epic]

As far as dominant and recessive genes are concerned (which they aren't, because they're just genes, but that's beside the point)...

Genes that determine skin and eye color: since brown eyes and dark skin tend to be dominant over blue and green eyes and fair skin, would that imply that people with dark skin and eyes are genetically superior than those with fair skin and light-colored eyes?

 

[Modified]

As far as dominant and recessive genes are concerned (which they aren't, because they're just genes, but that's beside the point)...

Genes that determine skin and eye color: since brown eyes and dark skin tend to be dominant over blue and green eyes and fair skin, would that imply that people with dark skin and eyes are genetically superior than those with fair skin and light-colored eyes?

This is purely a guess, but might it mean that severe sunburn is more detrimental to survival and reproductive success than vitamin D deficiency?

 

[chris epic]

Well, geography makes color-genetics, as well as other physicalities, relative to location.

So with that, I can see that I'm not on the right track- genetic dominance is not synonymous with genetic superiority, or ethnic superiority.

But then again, why is one color dominant over the other? Does this imply that the regions where these genetically dominant features developed are more superior than the areas where where genetically recessive features developed? If so, why were humans able to adapt in these areas? Why would genetics breed "inferior" features to begin with?

As you can see, I'm not a student of genetics...but I'm willing to be.

 

[Soapy Sam]

"Superior" is a value - laden term.
In Africa- where humans seem to have spent the critical years of their evolution- the sun is hot and UV is abundant. The high percentage of skin cancers among white South Africans and Kenyans suggests that the high latitude mutations leading to pale skin and blue eyes are less favoured in the tropics than dark skin, dark hair, brown eyes.
On the other hand, a dark skinned ethnic Pakistani child living at 56 degrees north in less than sunny Scotland, may require vitamin supplements in her diet because her skin has so much melatonin it blocks sunlight (especially if she is Muslim and does not wear light clothes in summer), so she suffers from diseases like ricketts.

Genes interact with the environment- and the human environment includes culture.

The question is not which is "superior" in an overall sense, but which is best fitted to the context it finds itself in. Given modern human mobility, it's likely we are never optimally suited to any environment. We're a bunch of patchwork mongrels, really.

 

[Cuddles]

Firstly, there is no such thing as "superior", either in genetics, ethnicity or geography.

Whether a gene is recessive or dominant can have a number of different causes, one of which will simply be chance. In the case of skin and eye colour, it is an unavoidable consequence of what the genes actually do - make melatonin. Light skin and blue eyes aren't a result of different pigments, they are simply a lack of pigment. If you have two genes that don't make pigment (or at least not much), you will have light skin. If you have two that do, you will have dark skin. Obviously, if you have one that does and one that doesn't, you will make pigment and will have dark skin, although it may not be as dark as with two. Neither allele is "better", it is simply that if you have one that does something and one that doesn't, the one that does something will be noticed.

Soapy Sam has already explained why different characteristics evolve in different places. "Different" is the important word. What works under certain conditions may not work under others. Lungs are great in air, but not so hot underwater. Which is superior? Depends where you are.

 

[ponderingturtle]

Also with eye color it is not as simple as dominant and recessive, as genes can also be turned on and off in a variety of ways.

 

[Lucky]

Genes that determine skin and eye color: since brown eyes and dark skin tend to be dominant over blue and green eyes and fair skin, would that imply that people with dark skin and eyes are genetically superior than those with fair skin and light-colored eyes?

The answer to that is a resounding "No!!! (And why on earth should it?)".

But what a wonderfully bizarre misunderstanding!

chris epic, understand this:
1) Dominant/recessive properties of genes
and
2) Selective advantage/disadvantage of those genes' effects in the body
are (conceptually) absolutely, utterly, totally, out-and-out separate issues.

Dominant/recessive properties determine at cell level which of a pair of alleles is expressed if they are different in an individual. (For many genes, the simple dominant/recessive system does not apply, btw.) This has nothing whatever to do with which allele (assuming it is expressed) gives the body a selective advantage over the other. We can take the dominant/recessive properties of a pair of alleles as a given, along with their other effects in the body, and study the variation and evolution of their frequencies in populations in an attempt to deduce the selective advantage/disadvantage of each allele.

Now that you've got that (I hope), I'll admit that it's an over-simplification. In principle, the effects of any gene in the body (including dominant/recessive properties) can be modified by other genes, so could indeed be subject to selection. But in general we do not assume that dominance implies selective advantage.

There are a number of other very important related issues to consider if you want even a basic understanding of this subject:
1) As Soapy pointed out, where different alleles exist in a population this usually indicates that one is not superior overall to the other. And superiority/inferiority of an allele often varies between populations.
2) Even if there was an overall superiority, this would apply to that gene only, not to the entire genome, still less to the individual.
3) Generally, characteristics (such as eye and skin colour) are affected by multiple genes, which can interact in very complex ways.
4) The dominant/recessive system isn't the universal rule. For example, the heterozygous individual may be different from either homozygous type (and may have a selective advantage over both).

This article on variation in human skin colour explains some of the complexities, and also indicates what we don't yet know.

 

[chris epic]

The question is not which is "superior" in an overall sense, but which is best fitted to the context it finds itself in.

Yes, that wasn't my question. I understand that color and other human physicalities are relative to their geographic location and climate. My question is, on a molecular level, my are the "dark" genes dominant over the "fair" genes. If this ties in with evolution, why are dark genes "gentically favored" over the fair-color genes.

For example, one observation I have made with European-Far East offspring is that the brown eyes and dark hair usually trump the light eyes and light hair.

My wife is Filipino. I think it would be cool if at least of our kids got my blue eyes, but as far as genetic propensity goes, the odds are against it. That is what bolstered my curiosity and following inquiry. Be careful not to assume that I'm just ignorant.

 

[Lucky]

My question is, on a molecular level, my are the "dark" genes dominant over the "fair" genes. If this ties in with evolution, why are dark genes "gentically favored" over the fair-color genes.

If you read my previous post you may be able to correct this basic misunderstanding. Dominant/recessive properties of genes at a molecular level are completely distinct from any evolutionary advantage/disadvantage conferred by rival genes.

It is also completely untrue that 'dark' genes are favoured over 'fair' ones in an evolutionary sense. If this were the case then fair skin and blue eyes would have disappeared long ago. There is absolutely no evidence of a general, worldwide selection pressure in the direction of darker skin etc.

Your term "genetically favored" doesn't mean anything – you could be talking either about dominance/recessiveness or evolutionary advantage/disadvantage (which is precisely the confusion).

 

[Soapy Sam]

I try to assume as little as possible about posters I don't know, but all I can go on is the content of their posts. My reply was to the question in the OP- " since brown eyes and dark skin tend to be dominant over blue and green eyes and fair skin, would that imply that people with dark skin and eyes are genetically superior than those with fair skin and light-colored eyes?"

-and not to the later question in your post 3, which was not there when I started to compose my post 4. The phrasing of the section in bold font sets off alarm bells, perhaps unintentionally. The use of "superior" in that context is not something I would expect of anyone even reasonably knowledgable about genetics. The brusque answer to the question would be a stark "No.", but that would be unhelpful and rude.

Oddly, I now find post 4 is shown as having an earlier time than post 3, which I find a bit baffling.
The answer to your second question, why is one allelle dominant, is, I suspect, a matter of complex biochemistry. I , too would be interested in an answer from anyone qualified to comment.

 

[trvlr2]

As far as dominant and recessive genes are concerned (which they aren't, because they're just genes, but that's beside the point)...

Genes that determine skin and eye color: since brown eyes and dark skin tend to be dominant over blue and green eyes and fair skin, would that imply that people with dark skin and eyes are genetically superior than those with fair skin and light-colored eyes?

"Superior genes" are those which survived to reproduce.

 

[Alric]

Ok. No more questions allowed unless you've read post #7

http://www.internationalskeptics.com/forums/showpost.php?p=3430796&postcount=7

That is the answer.

 

[Lucky]

The answer to your second question, why is one allelle dominant, is, I suspect, a matter of complex biochemistry. I , too would be interested in an answer from anyone qualified to comment.

From the article I linked to previously:

Melanin itself ... comes in two types, ... pheomelanin and ... eumelanin.
...
[T]he little we do know about common variation in human pigmentation involves pigment type-switching. The characteristic phenotype of fair skin, freckling, and carrot-red hair is associated with large amounts of pheomelanin and small amounts of eumelanin and is caused by loss-of-function alleles in a single gene, the melanocortin 1 receptor (MC1R). However, MC1R variation has a significant effect on pigmentation only in populations where red hair and fair skin are common.

That suggests that the dominance mechanism in this particular case is that an individual needs only one functioning copy of the gene that codes for the receptor – an additional copy will make little or no difference.

Ok. No more questions allowed unless you've read post #7

http://www.internationalskeptics.com/forums/showpost.php?p=3430796&postcount=7

That is the answer.

A red-letter day! Rare evidence that someone has read one of my painstaking, comprehensive (and possible a trifle tedious) posts in the Science forum.

 

[jimbob]

Further to post #7:

Is my understanding (essentially) correct below:

Devil's Advocate: "Suppose an allele (A) produces a prticular protein that another allele (a) of the same gene doesn't. If the organism has AA, protein is produced. If it has Aa or aA, protein is produced, if it has aa protein isn't produced. This allele "A" would look dominant over "a". "

 

[BenBurch]

Well, the Germans DID breed The Master Race;

 

[Alric]

Further to post #7:

Is my understanding (essentially) correct below:

Devil's Advocate: "Suppose an allele (A) produces a prticular protein that another allele (a) of the same gene doesn't. If the organism has AA, protein is produced. If it has Aa or aA, protein is produced, if it has aa protein isn't produced. This allele "A" would look dominant over "a". "

Correct. The same applies if (a) encodes a non-functional protein.

 

[Lucky]

Further to post #7:

Is my understanding (essentially) correct below:

Devil's Advocate: "Suppose an allele (A) produces a prticular protein that another allele (a) of the same gene doesn't. If the organism has AA, protein is produced. If it has Aa or aA, protein is produced, if it has aa protein isn't produced. This allele "A" would look dominant over "a". "

That's right; A would be dominant and a recessive. I gave an example in this post of a dominant/recessive system resulting from loss-of-function alleles.

But do not make the mistake of assuming that the functional allele is necessarily more advantageous in an evolutionary sense. It's quite usual for an evolving adaptation to depend on previously active genes becoming inactive (i.e. there is a selection pressure in favour of the recessive allele – though often other switching mechanisms are involved).

 

[chris epic]

Really, you all didn't need to bite your knuckle in aprehension, I'm not trying to be cute, and I'm not 'teetering' on the fence of racial superiority from genetics. I'm not Comte Gobineau.

All it took was a "Chris, my boy, your observations and assumptions are wrong: dark eyes, hair, and skin aren't automatically dominant over fair features."

But thanks for all the info.

 

[Complexity]

Really, you all didn't need to bite your knuckle in aprehension, I'm not trying to be cute, and I'm not 'teetering' on the fence of racial superiority from genetics. I'm not Comte Gobineau.

All it took was a "Chris, my boy, your observations and assumptions are wrong: dark eyes, hair, and skin aren't automatically dominant over fair features."

But thanks for all the info.

Chris - I don't think people are overreacting.

First, your question and the way that it was phrased raised some flags indicating that one of several unattractive patterns of thought may be in play. Careful response is appropriate.

Also, these forum threads aren't private conversations - they endure and will be read by many, often after the original participants aren't available for clarification. Careful response is appropriate.

 

[Soapy Sam]

From the article I linked to previously:


That suggests that the dominance mechanism in this particular case is that an individual needs only one functioning copy of the gene that codes for the receptor – an additional copy will make little or no difference.




A red-letter day! Rare evidence that someone has read one of my painstaking, comprehensive (and possible a trifle tedious) posts in the Science forum.

Don't underestimate yourself Lucky. Sometimes we read 'em , but just ain't smart enough to understand 'em.

Chris- what Complexity said. Hang around here a while and you start to detect patterns and similarities in new posts and posters- and you learn to react cautiously. Always happy to be proved wrong.