Race only skin deep - S.J. STUDENTS DISCOVER GENETIC LINK

Mercury News ^ | Mon, Feb. 09, 2004 | Katherine Corcoran

[CobaltBlue]

More than half of the class at San Jose's Piedmont Hills High School, students from numerous racial and ethnic backgrounds, are linked in their DNA to the same ancestor, born more than 100,000 years ago in central China or Taiwan.

[js1138]

Ping - cute story.

No thanks. This thread seems to have attracted the Hitler Youth Corps.

[Chris Talk]

This is really rather silly, and obvious, since science now believes that ALL humans are descended from a common ancestor in that same [100k yrs] time frame. Yawn, nothing to see here folks, move on...

This is no more remarkable than, in a creationist environment today or 200 yrs ago, to say that after all, we ought all to get along, we are all descended from Adam and Eve... The Bible goes on to say explicitly that we are all made from one flesh, in the beginning.

However, some very real and important differences have arisen since those idyllic primeval days. If you don't believe me, just TRY to get into Harvard, or a government job, if you are of my race! It is the GOVERNMENT itself that is declaring that race is all-important, it is THEY that are the "racists," and all rewards and positions in the USA are being handed out according to racial categories.

[Modernman]

Bad analogy. The right analogy would be between a Persian cat and a Siamese cat, which are, in fact, different.

How different are they? They can certainly breed with one another. I doubt that a Persian cat and a Siamese cat would see each other as different types of cat.

Similarly, if an alien looked at human beings without all of the cultural baggage we attach to one another, I doubt they would see any real differences.

And in our real world, ONLY certain races have black skin, or white skin, etc.

But that's simply a matter of how we define race. We look at skin color and say- black guy, white woman, whatever. However, those definitions have little to do with underlying biology. There are black people with lighter skin tones than certain white people. How about Indians? Or Iranians? What race do they belong to?

You start getting into South African or old South definitions of what constitutes a white person, black person etc. These definitons, by their very nature, are going to have arbitrary cut-offs that have nothing to do with biology.

Exactly! Think about it!

I'm being dense, I think. I don't get it.

[farmfriend]

Thanks for flagging this to me. BTTT

[spetznaz]

Bad analogy. The right analogy would be between a Persian cat and a Siamese cat, which are, in fact, different.

Actually it is a pretty good analogy puroresu. Race is basically one of those socio-cultural pseudo-biological what-nots. Science officially recognizes race as nothing more than a word.

Bad analogy again. The existence of variation within a race doesn't negate the differences between races. Suppose the tallest adult member of RACE A is 7 feet, and the shortest is 5 FEET. The tallest adult member of RACE B is 6 feet, and the shortest is 4 feet. There would be considerable variation within each race, and considerable overlap as well. But the fact would remain that ONLY RACE A grows to heights of 7 feet. And in our real world, ONLY certain races have black skin, or white skin, etc.

Deficient correlative judgment. And easily refuted. Based on geographical history size can be quite the divergent factor. For example Forest Elephants and Bush Elephants are totally alike ....except for their sizes (the forest tuskers are much smaller). Why? It is hard to survive well it a forest if you are big. Same thing with Nile crocodiles ....where the environment is optimal (eg numerous large prey) those crocs regularly attain sizes of 18 feet (some even 20 plus), while in other areas they rarely get to over 10 feet. Environmental factors.

.....Sickle-cell anemia....

Simplest explanation of all actually. The genesis of SCA stems from the fact that in Africa malaria is the biggest killer. Most of the continent has the anopheles mosquito, which transmits malaria (the female needs human blood to breed, and its saliva transmits the disease). A study was done that showed that Africans with SCA (and many have it ....especially around the lakes and river regions) have a surprisingly high resistance to malaria. The only drawback is that red blood cells for a person with SCA do not have a high efficacy level when it comes to oxyhemoglobin, hence the people easily get tired an what-not. However when you consider that malaria kills thousands a week in Africa then having SCA is an easy trade-off. Once again this is an environmental factor. Sadly when Africans came to the US those with the gene for SCA had all the bad side-effects and no positive (since the anopheles mosquito is not prevalent here).

Actually i remember this joint genetic analysis that was done between people of various tribes in Kenya, and it was noticed that there was more genetic variation between, say, a kikuyu and a maasai, than between either and a briton!

It is basically a pseudo-science .....on the same level as the whole 'once race is more intelligent than another B.S. In both cases the prevalent factor is NURTURING and ENVIRONMENT , with intelligence being due to the first and 'race' being due to eons of the second.

Classifying Humans As a first step to identifying links between social definitions of race and genetic heritage, scientists need a way to divide groups reliably according to their ancestry. Over the past 100,000 years or so, anatomically modern humans have migrated from Africa to other parts of the world, and members of our species have increased dramatically in number. This spread has left a distinct signature in our DNA.

To determine the degree of relatedness among groups, geneticists rely on tiny variations, or polymorphisms, in the DNA--specifically in the sequence of base pairs, the building blocks of DNA. Most of these polymorphisms do not occur within genes, the stretches of DNA that encode the information for making proteins (the molecules that constitute much of our bodies and carry out the chemical reactions of life). Accordingly, these common variations are neutral, in that they do not directly affect a particular trait. Some polymorphisms do occur in genes, however; these can contribute to individual variation in traits and to genetic diseases.

As scientists have sequenced the human genome (the full set of nuclear DNA), they have also identified millions of polymorphisms. The distribution of these polymorphisms across populations reflects the history of those populations and the effects of natural selection. To distinguish among groups, the ideal genetic polymorphism would be one that is present in all the members of one group and absent in the members of all other groups. But the major human groups have separated from one another too recently and have mixed too much for such differences to exist.

Polymorphisms that occur at different frequencies around the world can, however, be used to sort people roughly into groups. One useful class of polymorphisms consists of the Alus, short pieces of DNA that are similar in sequence to one another. Alus replicate occasionally, and the resulting copy splices itself at random into a new position on the original chromosome or on another chromosome, usually in a location that has no effect on the functioning of nearby genes. Each insertion is a unique event. Once an Alu sequence inserts itself, it can remain in place for eons, getting passed from one person to his or her descendants. Therefore, if two people have the same Alu sequence at the same spot in their genome, they must be descended from a common ancestor who gave them that specific segment of DNA.

[Agnes Heep]

I've always looked upon race as little more than an adaptation to climate. Asians, for example, have their eye folds, which limit light entering the pupil, and a greater mass to surface area ratio; this is the cold-weather type. It's just the opposite with blacks, whose dark skin filters UV rays and whose greater surface area to body mass (and hair texture) helps dissipate heat. Caucasians are the perfect temperate-climate type; nothing too extreme in any regard, which is great for the cool winters and warm summers of temperate zones. Of course human migration has landed many of each type in climates to which they're not physically adapted.

[CobaltBlue]

You have the timing off. Mitochondrial "Eve" existed (probably) about 200,000 years ago in Africa. Y-Chromosome "Adam" existed (probably) 60,000 years ago, also in Africa.

This is all new stuff, and exciting for those with a scientific turn of mind.

Only those whose brains are dead to the sense of wonder would yawn. Only people whose minds are closed would say "I've seen it all and have nothing to learn."

[CobaltBlue]

This thread seems to have attracted the Hitler Youth Corps.

The griping you hear is the sound of stretching, which can make the brain cells feel a mite sore. ;^)

[Modernman]

Asians, for example, have their eye folds, which limit light entering the pupil, and a greater mass to surface area ratio; this is the cold-weather type.

Many parts of Asia are much warmer than Europe, so I'm not sure if this holds up.

[ffusco]

Race does exist, but mass migartions of humans over the centuries have created mant different blends of different genetic material.

[Modernman]

Race does exist, but mass migartions of humans over the centuries have created mant different blends of different genetic material.

Two questions, then: 1) how would you define race, and how many races would you say there are and 2) if humans have blended so much over the ages, doesn't the concept of race therefore become irrelevant? (at least, biologically speaking)

[CobaltBlue]

Siamese cats and Persian cats are close enough related to mate. I once had four kittens from such a match - the dad was Siamese, the mom tabby Persian - three tabby kittens and one Seal Point with long fur. I kept one of the tabbies - she appeared to be an ordinary grey tabby shorthair.

Her first litter included two huge brown long haired tabbies that looked exactly like Maine Coon cats or Norwegian Forest cats - I never knew which local tom was the dad, but there was nobody around who looked like that as far as I knew.

[Chris Talk]

If my info is correct, then mitochondrial "Eve" has been brought down from your 200k years BP, to 150, then 140...then 110... and now hardly over 100k, as I stated...I believe she too must be brought down to the same sort of time frame as "Adam"... because...

"Adam was Eve's FATHER."

Think about it.

[Age of Reason]

Well then . . .

Since there's no such thing as race, it won't make a difference if we go back to the kind of immigration we had before 1964.

[LiteKeeper]

Yet, you cannot demonstrate that there are multiple races, regardless of your position on "origins." There is no genetic justification for dividing the human race into racial groups. By definition, one race should not be able to breed with another case, and that is simply not the case with humans. There are no "groupings" of humans that are unable to breed with other "groupings." The Australian aborigines, for instance, were thought to be a "different" race, and yet that have been able to interbreed with European settlers. It is simply not true that there are multiple races of Homo Sapiens.

[puroresu]

######How different are they? They can certainly breed with one another. I doubt that a Persian cat and a Siamese cat would see each other as different types of cat.######

If Persian and Siamese cats aren't different, then there's no reason why a male Persian cat couldn't mate with a female Persian cat and produce a Siamese offspring. A race is a subgroup of a larger species which, through genetic isolation, develops traits sufficiently different from other subgroups as to be genetically defined. Keep your Persian cats away from other breeds and they will absolutely never produce anything other than Persian offspring. Likewise, geographic isolation over the millennia explains why two Icelanders don't marry and give birth to a baby with the physical characteristics of, say, a Hottentot, and vice-versa.

It's not to assert that one is better than the other, just that they are genetically distinct. That's simply a fact.

######Similarly, if an alien looked at human beings without all of the cultural baggage we attach to one another, I doubt they would see any real differences.######

The entirety of human history says otherwise, and no better proof exists of that than the fact that the very people pushing the idea that race doesn't exist are, in fact, obsessed with race. Not to mention that cultural baggage, as you call it, has racial origins. If the Japanese had settled England, it would today have an Oriental culture.


######But that's simply a matter of how we define race. We look at skin color and say- black guy, white woman, whatever. However, those definitions have little to do with underlying biology. There are black people with lighter skin tones than certain white people. How about Indians? Or Iranians? What race do they belong to?######

######You start getting into South African or old South definitions of what constitutes a white person, black person etc. These definitons, by their very nature, are going to have arbitrary cut-offs that have nothing to do with biology.######

Well, races can mix, to be sure. But if they don't mix, they get further apart. If race was an illusion, that wouldn't happen. The great variety of races and ethnicities on earth is due to genetics and genetic isolation. I don't see why that simple fact frightens people so much. I appreciate other races and cultures. I love Japan and the Japanese people, for example. Race simply is. I see no reason to pervert science to pretend it isn't.

#####I'm being dense, I think. I don't get it.######

If genetic diseases can be transferred, then so can other genetic characteristics! :-)

[Doctor Stochastic]

The headline is a little misleading. The ancestor didn't have to live in China, only the progeny had to move there later.

Nonetheless, it's a good class project.

[puroresu]

You're very wrong, and I think you need to do a little more research on the human genome project.

As for nurturing and environment, try using those things to produce a black offspring from white parents, or vice-versa. If you can pull that off, I'll concede this debate.

[jpl]

If it's really true that there's no such thing as race, why do I find myself so frequently having to fill in those racial checkboxes on government forms?

[puroresu]

Races can mate and produce offspring if they are of the same overall species.

But if race was just a myth, then specific breeds of cats and dogs would be impossible to maintain.

And areas that were geographically isolated from one another for great periods would not produce people who, like dog and cat breeds, look very different from people in other geographic areas, possess different characteristics, and can be identified by DNA.