10/16/20 1711Course Business• Jefferson’s Blood ALA– Due next week– Info in last week’s lecture210/16/20 17210/10/17Modern Human Variation Part 23ALA#6• Do you agree that “race” is a cultural construct as opposed to a biological construct? Answer in a short paragraph410/16/20 173Tasks for Today• Human biological variation across the globe: the meaning of “the non-existence of biological races.”• The difference between genetic lineage history and race• Cultural Construction of Race, Ethnicity, and Biological Niche Construction• How does non-biological race have a biologically real effect on people’s health?56Three Discrete Variants?10/16/20 1747Portions of a spectrum appear discrete when viewed out of context8Colonial Period brings people together from the extremes, rather than from adjacent locations in the spectrum: the Historical Appearance of Scientific Racism810/16/20 1759Non-existence of Biological Race1) Races ≠ biological species. No reproductive isolation.10Non-existence of Biological Race2) Lewontin 1972 study of modern human populations: more genetic variation within geographical populations (85%) than between populations (15%).10/16/20 17611Non-existence of Biological Race3) Variation between human populations is HALF as large as the variation between chimpanzee populations.12Non-existence of Biological Race4) Races ≠ biological subspecies, the DNA evidence10/16/20 17713Even racists cannot agree on the number of “races”•Linneaus 1735: 4 (American, European, Asiatic, Negroid)•Buffon 1749: 6 (Laplander, Tartar, South Asiatic, European, Ethiopian, American)•Blumenbach 1781: 5 (Caucasoid, Mongoloid, American Indian, Ethiopian, Malay)•Cuvier 1790: 3 (Caucasoid, Mongoloid, Negroid)•Coon et al. 1950: 30 (“The foregoing list of 30 races might be 10 or 50”).•Boyd 1963: 6 (early European, European, African, Asiatic, American Indian, Australoid)•Coon 1965: 5 (Caucasoid, Mongoloid, Australoid, Congoid, Capoid)The Race ConceptAfrica:1410/16/20 17815Race is thus a cultural construction, not a biological construction.One can still detect lineage history within that 15% inter-population variation, BUT this history does not make “subspecies” or “races” because the variation is insignificant compared to the intra-population variation.LINEAGE HISTORY ≠ ESSENTIAL TYPES OF HUMANS OR EVEN GEOGRAPHICALLY-CONTIGUOUS INDIVIDUALS IN THE PAST1610/16/20 179The Lemba ethnic group from southern Africa with >half of their Y-chromosomes shared with Semitic populations rather than sub-Saharan populations17World Jewish Congress18NuclearDNAMitochondrialmtDNAMostly CodingMostly Non-codingMostly adaptation & a little historyMostly lineagehistory10/16/20 1710SNP Analysis (Single-nucleotide polymorphism)• Ordering or clustering samples (individuals) into lineages by the commonalities and uniquenesses in the sequence of nucleotides (A, C, T, G).1910/16/20 1711Figure 14.1653 Complete mitochondrial genomesNon-recombining part of 1062 Y-chromosomes21Forster 2004. mtDNA at 2-0 kya10/16/20 1712Forster 2004. mtDNA at 15-2 kyaForster 2004. mtDNA at 20-15 kya10/16/20 1713Forster 2004. mtDNA at 30-20 kyaForster 2004. mtDNA at 60-30 kya10/16/20 1714Forster 2004. mtDNA at 80-60 kyaForster 2004. mtDNA at 200-100 kya10/16/20 1715This is the ONLY real map: mtDNA at 2-0 kaRemember, there was likely no “recognized” group of people that equates to a Haplogroup10/16/20 1716Boyd & Silk, p. 393“ ‘A popular political statement now is, ‘There is no such thing as race.’ I wonder what people think when they hear this. They would have to suppose that the speaker, if he were dropped by parachute into downtown Nairobi, would be unable to tell, by looking around him, whether he was in Nairobi or Stockholm. This could only damage his credibility. The visible differences between different populations tell everyone that there is something here’ (Alice Brues, Discover magazine, p. 60).”31Boyd & Silk, p. 393“But our intuitions sometimes lead us astray. Our eyes tell us that the Earth is flat, but it is really a sphere. Our intuition tells us that a bullet fired horizontally from a rifle will hit the ground long after a bullet dropped from the muzzle at the same instant, yet in reality they will hit the ground at the same time. Our mind tells us that it is impossible for an elephant to have descended from a shrewlikeinsectivore, even though that is exactly what happened. The intuition that race is real is also an illusion.”3210/16/20 171733An individual is affected by their lineage history and genetic inheritance that may originate with a population that lived in a given selective environment. Can you think of any examples? BUT that lineage history may have LITTLE to do with their self-described affiliation.(think: sickle cell alleles in malarial regions; or lactase production with dairying).34Implications of Racial Ascription, i.e. RACISM • Racial identity is a cultural construct with little to do with the variation in biological traits between individuals.• The more obvious the phenotypic differences, the greater the chances of someone challenging an ethnic or racial affiliation.A cultural construct with a potentially HUGE biological consequence.10/16/20 171835Niche Construction• By changing one’s environment, one can change the selection pressures facing you & your kin within your life time.Remember how natural selection works…1) Variation in a trait2) Inheritance of the trait3) Variants of the trait cause differential reproductive success.36Niche Construction changes the environment’s ability to cause differential reproductive success given the individual’s traits.10/16/20 171937Flexibility of Race & Biological Niche Construction• By changing one’s environment, one can change the selection pressures facing you & your kin.• By changing one’s racial affiliation or ascription, you are changing selection pressures because you are changing the criteria by which people judge you & the perceptions they use against you.• Race = an ascribed status mostly dictated by the society• Ethnicity = a self-ascribed status mostly chosen by the individualDespite not being meaningful biological units , “race” and “ethnicity” have real biological effects on people’s lives…3810/16/20 1720Given the health disparities measured between “races” in America, can the biological reality of “race” be
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