Understanding Human Biological Variation

1. Understanding Human Biological Variation The Myth of Biological Races

2. The Context • “the problem of the 20th C” WE Dubois • global racism, global racial ideologies: the most important problem of the 21st C • Anthropology’s special position

3. Goal of this section of the course • Learn the most recent science of “race” • Understand the science of human biological variation • Examine pseudo-scientific claims about racial difference • Understand why racism, and the myth of racial differences, persist despite science

4. A Brief History of the Race Concept • Definition: subspecies • two populations • rarely or never interbreed, • genetically very different from one another • typological difference • 500 years ago: un-thinkable • race = essential part of the global discourse of power, Foucault on race and sex • race = deeply embedded in our cultural unconscious

5. “Race” science in the 19thC and 20thC • The logic of “race science”—or scientific racism • Typological model • see Stephen Jay Gould, The Mismeasure of Man • Typically three “races” (trait problem) • The methods employed • Seeds and lead pellets • Identifying what skulls go in what groups

6. The Turning of the Tide • Dubois and Boas, ~1920s • Boas: Ethnological research on Northwest Coast: biological traits flow and circulate • Boas: studies of European immigrant children skulls • importance of environment • by 1960, idea of race as biologically meaningful category debunked • But….my experience with this lecture “Papa” Franz Boas, ‘father’ of American Anthropology W.E. DuBois, leading early 20thC sociologist

7. The Demise of the Race Concept in Biology • Subspecies: clearly not the case • 3 traits • skin color • hair texture • facial physiognomy • do not co-vary • these traits = phenotypes, NOT genotypes • where is the line?

13. Where to Draw a Line?

14. Human Population Genetics • DNA, Genes, Alleles • Humans have thousands of genes • For each gene, asmany as 100 alleles* • We are polytypic • Distribution of alleles withinpopulations: Genefrequencies Simplified representation of a human chromosome pair * Weiss, Kenneth. 1998. Coming to Terms with Human Variation. Annual Review of Anthropology 27: 280

15. Lactose Tolerant People: Northern & Central Europeans Arabians North Indians the Fulani of W. Africa Lactose Intolerant People: Southern Europeans other African Populations East Asians Australian Aborigines Native Americans Other Ways of Making “Races” Looking at traits that are strongly genetic, and looking at gene frequencies—or the variation in how common the allele is in various populations

16. Other Ways of Making “Races” • Arched Fingerprints: • Black Africans, Europeans • Looped Fingerprints • Jewish people and some Indonesians • Whorled Fingerprints • Aboriginal Australians

17. Clinal or Populational? • Genetic variation between humans is low, 94% same* • by 1940s, scientists looking at difference as populational • today, evidence indicates difference is best understood as clinal, graduated across space, with occasional discontinuities yielding some populational differences *Marks, Jonathan. 1995. Human Biodiversity: Genes, Race and History. New York: Aldine de Grutyer

18. Hair color in Australia

19. Distribution of A Allele in world

20. Distribution of B Allele in E. Asia

21. Distribution of B Allele in Western Europe

22. Distribution of B Allele in World

23. Distribution of O Allele in World

24. Genetic Variation within and Between human populations • The genetic variation within any human population is greater than that between any of the purported races, and between any two populations • Greatest genetic variation known is among small camps of West Africans (10-20 people), or within this small group

25. Which of these athletes are closer genetically?

26. The problem of thinking genetically • Genotype v. phenotype • Human Genome Project; humans and roundworms • Genes, environment, proteins: complex web yields phenotype • (eg what genes make skin color, what genes make hair color, what genes make eye shape)

27. Evolutionary Evidence • Origins of all modern humans from African “Eve” • “Every person’s DNA is a mosaic of segments that originated at various times and in different places” (mit website on race science) • ..reshuffled combination of 30,000 genes from many different ancestors stretching back for generations.. • Everyone in the world today has pieces of ancient African genes in them

28. Evolutionary Evidence, con’d Relative genetic distance between populations • Continuous gene flow between populations • Differences are due largely to natural selection acting in specific • environments • If we had to do typologies, seven or more “races” in Africa, and everyone • native to elsewhere in the world in the eighth “race”

29. Human Biological Variation • Body Shape and Size • Allen’s Rule: big appendages • Bergman’s Rule: thick bodies • Skin color variation • melanin as protector from sun, inhibitor of Vitamin D • Sickle cell hemoglobins and malaria resistance

30. Distribution of Skin Color

31. “Human Nature” • Migration • Exchange/inter-marriage/gene flow • Perhaps these tendencies explain our “evolutionary success”—the fact that there are more and more of us all the time and we live all over—kind of like cockroaches……