Understanding Human Biological Variation

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Understanding Human Biological Variation

• The Myth of Biological Races

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The Context

• the problem of the 20th C WE Dubois
• global racism, global racial ideologies the most
  important problem of the 21st C
• Anthropologys special position

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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

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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

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Race science in the 19thC and 20thC

• The logic of race scienceor 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

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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
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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?

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Where to Draw a Line?
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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
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Other Ways of Making Races

• 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

Looking at traits that are strongly genetic, and
looking at gene frequenciesor the variation in
how common the allele is in various populations
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Other Ways of Making Races

• Arched Fingerprints
• Black Africans, Europeans
• Looped Fingerprints
• Jewish people and some Indonesians
• Whorled Fingerprints
• Aboriginal Australians

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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
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Hair color in Australia
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Distribution of A Allele in world
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Distribution of B Allele in E. Asia
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Distribution of B Allele in Western Europe
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Distribution of B Allele in World
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Distribution of O Allele in World
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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

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Which of these athletes are closer genetically?
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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)

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Evolutionary Evidence

• Origins of all modern humans from African Eve
• Every persons 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

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Evolutionary Evidence, cond
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

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Human Biological Variation

• Body Shape and Size
• Allens Rule big appendages
• Bergmans Rule thick bodies
• Skin color variation
• melanin as protector from sun, inhibitor of
  Vitamin D
• Sickle cell hemoglobins and malaria resistance

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Distribution of Skin Color
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Human Nature

• Migration
• Exchange/inter-marriage/gene flow
• Perhaps these tendencies explain our
  evolutionary successthe fact that there are
  more and more of us all the time and we live all
  overkind of like cockroaches