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Genetic basis for race ?

  1. Dec 18, 2003 #1
    Genetic basis for "race"?

    Now, I'm not sure if "race" is in any way a proper term in biology. However, I've seen a few threads here and there by Carlos Hernandez, and now I'm curious.

    There are differences among humans based on where we, and our ancestors, are from. Average heights, formations of teeth, skull shapes, et cetera. These differences do exist. In fact, they are noticable to the extent that coroners use them to identify decomposed bodies during examinations. They check the teeth, for example, and can tell by their shape what the person's "race" was.

    Such differences as skin colour are based in our genes. We don't spontaneously develop different skin colours due to some idiot roling dice after we're born. Our genes determine this physical factor of our makeup, and others.

    I don't consider any group inherently superior to another overall. However, among other animals, it is easy to see how one variety is superior to another in its home environment. For example, the small ponies in Mongolia are superior in Mongolia to Clydesdales, whereas a Clydesdale would kick the crap out of one of those ponies if, for some whacky reason, it was fightin' time. I think it is quite clear that darker skin pigmentation is superior for places which recieve greater amounts of sunlight. However, I don't think that idea fully explains the distribution of differences among humans. Some of the darkest skin can be found in mountain villages in New Guinea, which recieve rather low amounts of sunlight due to shadow from the mountains and high cloud cover.

    So, my questions...

    1) In formal biology terminology, is the word "race" used? If so, what is its proper definition?

    2) Do environmental conditions explain all differences among humans such as skin colour, skeletal differences, et cetera? Or for explanation must we also look to the diet available within an individual animal's lifetime? Must we also take into account things a loooooooooooooong time ago such as interbreeding between Homo Sapiens and Neanderthal, and other such hybridisation in other regions?


    PS: Sorry if this has all been covered before. I know nothing about biology, and those other threads sparked my curiousity.
     
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  3. Dec 18, 2003 #2
  4. Dec 18, 2003 #3

    selfAdjoint

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    There is genetic discrimination evidence for about five regional "groups". But the boundaries of the groups are fuzzy qand overlapping because the evidence is statistical, based on compared genomes. So these groups do NOT correspond exactly to the old, naive, concept of race, any more than the biological concept of species corresponds exactly with the biblical notion of "kind".
     
  5. Dec 18, 2003 #4

    adrenaline

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  6. Dec 18, 2003 #5
    We would have to have a standard for defining race. Perhaps original location of origins, physical characteristics, mental characteristics? It's really all about what characteristics individuals want to use to group individuals.

    Carlos Hernandez
     
  7. Dec 18, 2003 #6

    Monique

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    Re: Genetic basis for "race"?

    Formally? No. But is the measure still used to subdivide groups of research participants? Yes.

    I recently did a meta-analysis where I gathered allelic information for a couple of genes that come together with a disease phenotype. By doing this, you get data from all around the world. It could be analyzed as a bulk, but it is proper protocol to take the population variation into account.

    So, I had to subdivide my data in groups of Caucasian and African-American. I discarded data on other populations. Is it right? I actually don't think so. I mean, the definition of a Caucasian goes from Finland to Saudi Arabia, from Poland to India. Not to speak about African Americans..


    There are certain characteristics that go together with a population, population genetics is a popular topic of research these days. But these are geographically and socially isolated populations, not a racial group.

    I think the idea of race is wrong, but it is important to take the ethnic heritage into account.
     
  8. Dec 19, 2003 #7

    adrenaline

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    Re: Re: Genetic basis for "race"?

    you hit the nail on the head monique. It is a hot topic in the medical research area where diseases and drug response may have different effects depending on "race" but not defined in the traditional sense. I think population genetics would be a better terminology as you implied since outward physical characteristics can still belie the genetic similarities or differences you and the article implied.
     
  9. Dec 19, 2003 #8

    Monique

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    Re: Re: Re: Genetic basis for "race"?

    No, environmental conditions do not explain all differences among humans, because we aren't superhumans which are at the end of evolution. Africans are generally very thin and long, while Inuits for instance are very short and round. This has to do with maintaining proper body temperature, but not all Africans are long and thin. This might be due to nutrition, but also to an uncommon gene.

    Why would you have to take into account inbreeding between Homo sapiens and the Neantherthal? This would have taken place (most probably?) before the separation of races. I am not sure though. I believe the Neantherthal mainly lived in the region now France.. maybe some evidence still lies in the DNA of the people??

    To expand on the racial definition.

    It is true that each population has its own allele frequencies. In the case of a very old allele, it is possible that for instance the Caucasian population all are carrier, but that Asian populations don't have that particular allele. This is where customization of medication comes into play, researchers are conducting research on the idea that some people might not benifit from certain medication because of their genetic makeup, in case of an old mutation this would be on a racial level.

    But small population differ as much from eachother as racial ones would. Take for instance Finland, it is a population which has been isolated by several factors: cold weather and language barriers (Russia and Sweden on either side). It has also had several bottlenecks (plague and starvation), creating a founder effect. This population is in fact very interesting to study, because of its history and the people have very different allele frequencies than other countries. Actually, a company is making a DNA chip, to be used especially for this population carrying SNPs (single nucleotide polymorphism (type of mutation of DNA)) called the FinChip, to be used for Biomedical Research.

    So that is geographically isolated population, some socially isolated populations would be the Mormons, the Hutterites, the Mennonites. These populations get free medical checkups and all the data is used together with information on their genomes to find medically important mutations.

    There are so many examples I could give you. So basically: yes, there is a difference between people from Africa and Asia. Mostly due to relatively old (but not too old) conserved mutations. But recent populations histories (lots of invasions, bottlenecks, population growth) are of greater importance and generate lots of subgroups which can be very different.

    And now with the mobility of people, the differences between different populations will get smaller and smaller..
     
  10. Dec 19, 2003 #9
    For protection from various biological hazards of the future, I suppose our modern ease of transport and mixing of people from everywhere is good for the species? The more combinations we have, the more likely there will be people to resist a virus, environmental problem, or another threat?
     
  11. Dec 19, 2003 #10

    Monique

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    Yes, but ultimately it should lead to a very homogenious human population (not sure what that time scale would be) so that would not be that benificial..

    About the isolated populations. I just had the Dilight! to find out that there are a lot of lectures available for viewing online!! I really never knew that and it is SO cool! but anyway,

    Here is a lecture of Leena Peltonen, M.D., Ph.D. who has a position at National Public Health Institute of Finland and at UCLA. She is one of the leading figures in population genetics! I had the pleasure to meat her twice, once in the US and once in Italy :wink: *showing off*

    http://www.arc.ucla.edu/streaming/peltonen.htm Using isolated populations to detect disease genes. the realplayer link worked for me..
     
  12. Dec 19, 2003 #11
    Pretty interesting lecture. What was that she ended with about getting your entire genetic profile on a 'credit card' so you could predict what diseases you might get? (maybe in 20 years or so)
     
  13. Dec 20, 2003 #12

    Monique

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    Yes, the first 5-7 minutes are not so good, but after that she gives a nice overview.

    What did you think about the lactose intolerance example? For those who would like to hear it, it is at 31min30sec in the lecture.

    Well, the genetic profile she was talking about is that in a few years (not 20) we would have a good enough knowledge about the type of mutations which are responsible for development of disease. You could then test an individual for all these mutations and make a profile ('horoscope') for such an individual about the disease it is predisposed to.

    Did you see the movie GATACA? It talks about that type of testing, when a baby is born a heel prick is done and the blood is put into a machine and the whole sequence rolls out with a disease profile. The individual was a love-baby (not a matched baby to prevent bad gene combinations) so it was labeled as being a 'bastard' and had a 80%predisposition for developing heart disease. The baby grew up and wanted to become an astronaut, but couldn't because of its genetic make-up.

    But as Dr. Peltonen pointed out, we are not ruled by our genetic profile. Environmental conditions play a huge role and we would need to determine their influence before we can make such profiles. She showed a slide of three genes, and the effect it has in different individuals.

    A clear example would be alcohol intolerance. You can sequence a person and say you have alcohol dehydrogenase deficiency and tell them that they will die of liver cirrosis. Well, but if the person never consumes alcohol, the environmental effect is taken away and the person will never notice its genetic deficiency.

    Another problem is the mutation/clinical manifestation uncorrelation in many diseases. Some genetic diseases are very simple and affect a single pathway which is non-redundant. The same mutation will always lead to the same phenotype. In reality, a gene affects multiple pathways and there might be redundancy in those pathways, which by-passes the deficiency. In such cases it is impossible to predict what the effect of a mutation in a gene will be.

    An interesting example is that of monozygosic (identical) twins. They carry the exact same mutation, grow up in the same family. Both have 100% of the same genes and the same enzyme deficiency. One of them lives a healthy life and the other becomes and stays severely ill by the mutation. Why, you may ask? Well, both had an infection as a child, the one was sick for a few days shorter than the other, this event was the trigger which set off the accumulation of the protein which could not be metabolized in the one. This accumulation did not lead to such high levels in the other person, which was able to recover..
     
  14. Dec 20, 2003 #13

    Monique

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    more lectures!!!

    From the National Institutes of Health (NIH)
    http://videocast.nih.gov/PastEvents.asp?c=35

    White and African-American Genetic Explanations for Gender, Class, and Race Differences Thursday, June 20, 2002
     
  15. Dec 20, 2003 #14

    adrenaline

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    You are more the expert, but aren't we coming to the conclusion that the epigenetic material or the material outside the actual genetic code has just as much influence on the expression of how a disease will manifest? I believe the field of oncology, this is becoming the rage in terms of how the environment actually influences a "cancer" gene.
     
  16. Dec 20, 2003 #15

    Monique

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    Well, it depends entirely on the gene and the mutation. Especially for monogenic disorders there is a strong correlation between genotype and phenotype. But things aren't always that easy.

    Maybe in the future when we have more knowledge about all the interacting genes and proteins, it will be easier to understand the processes. Right now we label a genetic disorder 'complex' when we have no clue about its inheritance pattern, that might all change with time.

    The monozygotic twin example I gave is an exception to the norm, that's why it is an interesting illustration that we can't always predict what will happen.
     
  17. Dec 20, 2003 #16
    Let me post an excerpt from http://home.comcast.net/~neoeugenics/tab.htm

    "Diamond offered a more colorful version of an argument advanced in 1972 by Richard Lewontin, a Harvard University geneticist. Lewontin had become convinced that virtually all meaningful differences between races are either random or culturally determined. Based on his review of the available data, he concluded that only a tiny fraction of the differences between individuals could be considered "racial." In other words, Lewontin maintained that the differences that separate "races" are little more than what distinguishes two random fans at a World Cup match--statistically nothing, genetically speaking. The article, published in the prestigious journal Evolutionary Biology, amounted to a frontal attack on the concept of race.

    For sure genetic differences between any two individuals are extremely small in percentage terms. Coming from a geneticist, rather than a sociologist or anthropologist, Lewontin's article had enormous influence, although not everyone was convinced. Lewontin's finding that on average humans share 99.8 percent of genetic material and that any two individuals are apt to share considerably more than 90 percent of this shared genetic library is on target. Interpreting that data is another issue, however. Lewontin's analysis suffers both scientifically and politically.

    Although the politics of a scientist is not necessarily an issue in evaluating their work, in Lewontin's case it is crucial. According to his own account, his sensibilities were catalyzed by the civil rights movement of the 1960s. He made it very clear that his science was in part a mission to reaffirm our common humanity. To geneticists and biologists with less of an avowed agenda, Lewontin appeared to leaven his conclusion with his personal ideology.

    From a scientific perspective, Lewontin and those that have relied on his work have reached beyond the data to some tenuous conclusions. In fact the percentage of differences is a far less important issue than which genes are different. Even minute differences in DNA can have profound effects on how an animal or human looks and acts while huge apparent variations between species may be almost insignificant in genetic terms. Consider the cichlid fish, which can be found in Africa's Lake Nyas. The cichlid, which has differentiated from one species to hundreds over a mere 11,500 years, "differ among themselves as much as do tigers and cows," Jared Diamond has noted. "Some graze on algae, others catch other fish, and still others variously crush snails, feed on plankton, catch insects, nibble the scales off other fish, or specialize in grabbing fish embryos from brooding mother fish." The kicker, these variations are the result of infinitesimal genetic differences--about 0.4 percent of their DNA studied.

    In humans too, it is not the percentage of genes that is most critical, but whether and how the genes impact our physiology or behavior. Diamond mused that if an alien were to arrive on our planet and analyze our DNA, humans would appear, from a genetic perspective, as a third race of chimpanzees. Although it is believed they took a different evolutionary path from humans only five million years ago, chimps share fully 98.4 percent of our DNA. Just 50 out of 100,000 genes that humans and chimps are thought to possess--or a minuscule 0.3 percent--may account for all of the cognitive differences between man and ape. For that matter, dogs share about 95 percent of our genome; even the tiny roundworm, barely visible to the naked eye, share about 74 percent of its genes with humans.

    Most mammalian genes, as much as 70 percent, are "junk" that have accumulated over the course of evolution with absolutely no remaining function; whether they are similar or different is meaningless. But the key 1.4 percent of regulatory genes can and do have a huge impact on all aspects of our humanity. In other words, small genetic differences do not automatically translate into trivial bodily or behavioral variations. The critical factor is not which genes are passed along but how they are patterned and what traits they influence.

    Lewontin did collate genetic variability from known genetic markers and find that most of it lay within and not between human populations. Numerous scientists since have generalized those findings to the entire human genome, yet no such study has been done. Now it is believed that such an inference is dicey at best. The trouble with genetic markers is that they display "junk" variability that sends a signal that variability within populations exceeds variability between populations. However, the "junk" DNA that has not been weeded out by natural selection accounts for a larger proportion of within-population variability. Genetic makers may therefore be sending an exaggerated and maybe false signal. In contrast, the harder-to-study regulatory genes (that circumscribe our physical and athletic abilities) signal that between-group variability is far larger than has been believed. In other words, human populations are genetically more different than Lewontin and others who have relied on his work realize.
     
  18. Dec 20, 2003 #17
  19. Dec 20, 2003 #18

    Monique

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    Carlos, I never read links which end at .com or .net if it comes to proving a point..
     
  20. Dec 20, 2003 #19

    Monique

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    Did you know that your commonsenseclub.com is a racist website, advocating a nation consisting of only white people, linking violence and crimility to blacks? Just read their mission statement..
     
  21. Dec 20, 2003 #20
    Well, that is an irrational behavior, but to each his own.

    Regards,

    Carlos Hernandez
     
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