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Blacks have trouble clearing cervical cancer virus
Source: AP-Excite
By MARILYNN MARCHIONE
CHICAGO (AP) - Provocative new research might help explain why black women are so much more likely than whites to develop and die from cervical cancer: They seem to have more trouble clearing HPV, the virus that causes the disease.
Doctors have long thought that less access to screening and follow-up health care were the reasons black women are 40 percent more likely to develop cervical cancer and twice as likely to die from it. The new study involving young college women suggests there might be a biological explanation for the racial disparity, too.
If further study confirms this novel finding, it would make the HPV vaccine even more important for black women, said Worta McCaskill-Stevens, a prevention specialist at the National Cancer Institute. The vaccine is recommended for all girls starting at age 11.
The study was presented Sunday at an American Association for Cancer Research conference in Chicago.
Read more: http://apnews.excite.com/article/20120401/D9TS84J81.html
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Lewontin's argument and criticism
In 1972 Richard Lewontin performed a FST statistical analysis using 17 markers including blood group proteins. His results were that the majority of genetic differences between humans, 85.4%, were found within a population, 8.3% of genetic differences were found between populations within a race, and only 6.3% was found to differentiate races which in the study were Caucasian, African, Mongoloid, South Asian Aborigines, Amerinds, Oceanians, and Australian Aborigines. Since then, other analyses have found FST values of 6%-10% between continental human groups, 5-15% between different populations occupying the same continent, and 75-85% within populations.[23][24][25][26] Lewontin's argument led a number of authors publishing in the 1990s and 2000s to follow Lewontin's verdict that race is biologically a meaningless concept.
While acknowledging the correctness of Lewontin's observation that racial groups are genetically homogeneous, geneticist A. W. F. Edwards in the paper "Human Genetic Diversity: Lewontin's Fallacy" (2003) argued that the conclusion that racial groups can not be genetically distinguished from each other is incorrect. Edwards argued that when multiple allelles are taken into account genetic differences do tend to cluster in geographic patterns roughly corresponding to the groups commonly defined as races. This is because most of the information that distinguishes populations from each other is hidden in the correlation structure of allele frequencies, making it possible to highly reliably classify individuals using the mathematical techniques described above. Edwards argued that, even if the probability of misclassifying an individual based on a single genetic marker is as high as 30% (as Lewontin reported in 1972), the misclassification probability becomes close to zero if enough genetic markers are studied simultaneously. Edwards saw Lewontin's argument as being based mostly in a political stance that denies the existence biological difference in order to argue for social equality. [4]
Richard Dawkins (2005) agreed with Edwards' view, summarizing the argument against Lewontin as being, "However small the racial partition of the total variation may be, if such racial characteristics as there are highly correlate with other racial characteristics, they are by definition informative, and therefore of taxonomic significance."[27]
Alan Templeton (2003) argued that in the nonhuman literature an FST of at least 25%-30% is a standard criterion for the identification of a subspecies.[24] John Goodrum has noted that Templeton incorrectly cited this figure from a 1997 article from Herpetological Review entitled “Subspecies and Classification".[28] The authors of that paper do not refer to Fst values. They are referring the 75 percent rule for subspecies.[29]
Henry Harpending (2002) has argued that the magnitude of human FST values imply that "kinship between two individuals of the same human population is equivalent to kinship between grandparent and grandchild or between half siblings. The widespread assertion that this is small and insignificant should be reexamined." [30]
Sarich and Miele (2004) have argued that estimates of genetic difference between individuals of different populations fail to take into account human diploidity. "The point is that we are diploid organisms, getting one set of chromosomes from one parent and a second from the other. To the extent that your mother and father are not especially closely related, then, those two sets of chromosomes will come close to being a random sample of the chromosomes in your population. And the sets present in some randomly chosen member of yours will also be about as different from your two sets as they are from one another. So how much of the variability will be distributed where? First is the 15 percent that is interpopulational. The other 85 percent will then split half and half (42.5 percent) between the intra- and interindividual within-population comparisons. The increase in variability in between-population comparisons is thus 15 percent against the 42.5 percent that is between-individual within-population. Thus, 15/42.5 is 32.5 percent, a much more impressive and, more important, more legitimate value than 15 percent."[31]
Anthropologists such as C. Loring Brace[32] and Jonathan Kaplan[33] and geneticist Joseph Graves,[34] have argued that while there it is certainly possible to find biological and genetic variation that corresponds roughly to the groupings normally defined as races, this is true for almost all geographically distinct populations. The cluster structure of the genetic data is therefore dependent on the initial hypotheses of the researcher and the populations sampled. When one samples continental groups the clusters become continental, if one had chosen other sampling patterns the clusters would be different. Weiss and Fullerton have noted that if one sampled only Icelanders, Mayans and Maoris, three distinct clusters would form and all other populations could be described as being composed of admixtures of Maori, Icelandic and Mayan genetic materials.[35] Kaplan therefore argues that seen in this way both Lewontin and Edwards are right in their arguments. He concludes that while racial groups are characterized by different allele frequencies, this does not mean that racial classification is a natural taxonomy of the human species, because multiple other genetic patterns can be found in human populations that crosscut racial distinctions. In this view racial groupings are social constructions that also have biological reality which is largely an artefact of how the category has been constructed.
http://en.wikipedia.org/wiki/Race_and_genetics#Race_and_population_genetic_structure
Thanks, well said.
Well, my post is almost as good as yours but I still have a ways to go.