About human races

1
About human races

• There are obvious biological differences in human
  beings.
• Two important questions about this fact are
• 1) which criteria, which measurable differences,
  shall we use to set up a typology of races? and
• 2) Assuming we can accurately measure human
  phenotypical physical variation, does this have
  anything to do with variation in features of
  human thought or behavior?

2
Classification

• On the question of classification, there are
  historically two very different modes of
  thinking
• (1) typological thinking and
• (2) population thinking

3
Blumenbachs races

• 1775 Johann Friedrich Blumenbach used the term
  race to define divisions of the human species.
• He classified humans into five races Caucasian,
  Mongolian, Ethiopian, American, and Malay.
• Blumenbach held that there was but one species of
  human, but he concluded that humans from the
  Caucasus region of Asia Minor were aesthetically
  pleasing.

4
Blumenbachs race map
http//tinyurl.com/oz3h9
5
Typological thinking

• Blumenbach classified skulls from around the
  world by studying detail and selecting a type
  specimen.
• Typological thinking is still with us today.

6

• The logical fallacy in typological thinking is a
  general problem, not confined to the labeling of
  so-called races.
• We see it in the labeling of particular dialects
  as typical of a language.

7
Population thinking

• The remedy for typological studies about races of
  humans appeared to be population studies.
• Measure a large numbers of individuals, and
  produce means and distributions.
• This creates ideal types, the features of which
  are found in no individual.
• And the more precise the measures, the more
  categories are proliferated.

8
Creating complexity

• If there are four races based on color (black,
  white, yellow, red) and we add one binary feature
  (like hair texture wavy and straight) then
  there are eight races.
• Now add two kinds of crania (wide and narrow)
  there are 16 types.
• Sweden, 1898 of 45,000 people, 11 had all the
  traits usually included in the so-called Nordic
  race blond hair, blue eyes, low skin
  pigmentation, dolicocephaly, and so on.

9

• Suppose 20 traits and a criterion that 75 of
  people have each one.
• By trait 2 75 of 75 is 56
• By trait 10 1.34 have 75 of the traits.
• By trait 20 317 people out of 100,000 have all
  the traits. Those are the ideal candidates.

10
We impose typologies

• All typologies are arbitrary in some sense.
• We impose them on nature to make sense out of a
  welter of information. Here are seven historical
  typologies of humans
• 1) cephalic index, or the ratio between the width
  and the length of the head 2) the facial index,
  or the ratio of the length to the width of the
  face 3) the nasal index 4) eye, lip, and ear
  shape 5) eye, hair, and skin color and hair
  texture 6) stature, weight, and build and 7)
  blood groups.

11
Race is a social concept

• But every morphological characteristic has a
  range of variation a distribution even within
  so-called races.
• Look, for example, at skin color in the U.S.
• Historically, the one-drop rule defined what it
  meant to be black for many people.
• Many Mediterranean people have more melanin in
  their skin than do many American blacks.

12
Race is a folkloric concept

• Race is a folkloric idea that developed in the
  U.S. out of the debate over slavery.
• 17th century, British used Indian slaves on
  plantations in Barbados and Jamaica.
• By the late 17th century, the Indians had died
  and Britain began bringing slaves from Africa to
  the plantations in their Caribbean colonies.
• Recall in the early 18th century, the
  anti-slavery movement in Britain was underway.

13
Establishing the social concept of race

• 1854 Types of Mankind published by Josiah Nott
  (a Southern physician) and George Glidden (the
  U.S. consul in Cairo).
• Nine editions before 1900 helped establish the
  social concept of race.

14
Social race becomes law

• Roger Taney, Chief Justice of the United States
  Supreme Court in 1859 in the Dred Scott case
• Negroes were seen only as property they were
  never thought of or spoken of except as property
  and thus were not intended by the framers of the
  Constitution to be accorded citizenship rights.
  The Negro, Taney said, is a different order of
  being.

15
Science ratifies social race

• In the 18th and 19th century, the folk idea of
  race was ratified by science.
• In the 20th century, population thinking and
  genetics seemed to be the answer We would
  recognize that races are not merely ideal types,
  based on measurements of phenotypic differences,
  but are populations that are identified by a
  common gene pool and that tend to preserve that
  gene pool over time.

16

• Genes are distributed across populations, but
  there are concentrations that is, the frequency
  of particular genes varies greatly and it is this
  fact which changed thinking about races.
• Just as everyone is unique phenotypically, so we
  are all unique genetically, but there are clumps
  of traits based on genetic frequencies.

17
Sophisticated typological thinking

• And so we wound up with a definition of race that
  was more sophisticated than those of earlier
  times, but just as flawed.
• Here is the scientific definition of race, based
  on population thinking
• A race is a human population that is sufficiently
  inbred to reveal a distinctive genetic
  composition which is observable in a distinctive
  combination of physical traits.

18
A typology by any other name

• This is just another way of creating typologies.
• Human variation is continuous, with no clear
  boundaries, and race whether based on ideal
  types or on genetic populations tells us little
  about a person.
• The variation within races, at the individual
  level, are far greater than the variations across
  the so-called races.

19
Race as a sociopolitical concept

• Now we have populations tagged as races, with the
  tagging becoming more and more sociopolitically
  motivated.
• Biological race does not explain infant mortality
  among American Indians on the Reservations or
  among African Americans in the inner cities.
• Biological race does not explain the high rate of
  breast cancer in African American women or the
  low life expectancy in African American men.

20
Race is ephemeral

• In Brazil, rich people who have dark skin and
  wiry hair are classified in a higher social race
  than if they were poor.
• Skin color as a race marker is ephemeral
  Amazonian Indians are darker than North American
  Indians are.

21
Race, language, class

• The concept of race is much like the concept of
  social class or the concept of English as a
  language.
• Each implies an aggregate of people who have
  something in common and in each case, diversity
  among the constituents is put aside.

22

• So, the concept of race in humans is a social,
  not a biological concept.
• There are clumps of physical features that define
  populations, but we dont have to use skin color
  to to group geographic populations.

23
Ear wax does very well

• Suppose you have to guess whether each of 300
  people is from China, Sweden or Kenya.
• You cant see them but you have a sample of their
  ear wax.
• If the wax were dry and crumbly, then guess
  Chinese. Otherwise, guess not Chinese. Across
  China, crumbly ear wax occurs in 86-98 of
  sampled persons, so guessing Chinese produces
  about one mistake in 10-12 tries. Not a bad
  score.

24

• Crumbly, dry ear wax 18 of northern Europeans
  and
• So if the sample of ear wax is wet and gooey
  rather than dry and crumbly, youd make very few
  mistakes if you guess that the person was either
  African or northern European.

25
Duffy factor

• Now take a sample of blood.
• If there is no Duffy factor in the red blood
  cells, then guess Kenyan.
• Individuals who lack the Duffy factor are not
  susceptible to Plasmodium vivax.
• Duffy factor is present in almost all Chinese and
  varies across northern European populations from
  37 to 82.

26
Melanin and skin Color

• The skin color of all animals is highly plastic.
• The case of the English peppered moth
• By the mid-19th century, the Industrial
  Revolution produces pollution in the English
  countryside.
• Peppered moth splits into becomes two varieties,
  one melanic, one lighter and the melanic variety
  predominates by 1896 in the more polluted areas.
• Under UV light, the melanic form of the moth is
  protected from birds.

27

• From 1960-1980, the percentage of melanic moths
  goes from 90 to 10, as pollution controls take
  effect.

28

• The sparrow was introduced into the U.S. in 1852
  from Europe onto the east coast.
• Heavier varieties now in the northern, colder
  areas and the lighter varieties are in southern,
  warm areas.
• 100 sparrow generations. For humans, this would
  be 2000 years.

29
Skin color and malaria

• In humans, melanin is formed in special cells,
  melanocytes, in the lower epidermis.
• Populations father to the north from the equator
  average less and less melanin production.
• Vitamin D production in deep layers of skin and
  is stimulated by UV light.
• In hypovitaminoisis D calcium is not absorbed in
  the intestines. The nervous system draws needed D
  from bone and this produces rickets.

30

• Rickets widespread in 19th century Europe with
  industrialization.
• Hypervitaminosis D leads to fatal kidney
  dysfunction.
• Light-skinned, northern Europeans can absorb
  enough UV light to produce vitamin D, but have a
  higher risk of later-life skin cancer.

31

• Hemoglobin protein in erythrocytes transports
  oxygen to tissues and returns with carbon dioxide
  to the lungs.
• Hemoglobin molecules are two protein chains.
• The 6th amino acid on one chain is glutamic acid.
• A mutation at this spot can change the thymine
  base to adenine that is, it can change the
  amino acid from a CTC to a CAC.
• This single event is the allele of hemoglobin
  known as sickle-cell, or HgS.

32

• Central Africa Hemoglobin S molecules
  crystallize when the oxygen level is low and
  become twisted.
• This is sickle-cell anemia.
• 1951 JV Neel showed that carriers of the sickle
  cell trait are heterozygous.
• They have cells with the same property, but it is
  not severe in terms of response.

33

• Two hemoglobins, S and A.
• SS die of sickle-cell disease before reproducing
• AA, homozygous normals, more likely to die of
  malaria
• AS heterozygotes less likely to die of malaria.
• Balanced polymorphism

34
Balanced polymorphism

• 2000 years ago, people began moving into forest
  from open dry country.
• They used metal tools to clear forest patches for
  agriculture.
• This produced densely populated settlements and
  standing puddles of water.

35

• 1954, AC Allison plots distribution of HbS and
  malaria parasites the Plasmodium falciparum and
  the Plasmodium vivax.
• 1967, SL Wiesenfeld (Science) shows correlation
  between the length of time that agriculture was
  in a region in Africa and the frequency of the
  sickle-cell trait.

36

• Heterozygotes HbS/HbA resist malaria, creating
  balanced polymorphism
• Different pressure in various places from
  malaria, but there is uniform pressure against
  sickle cell anemia.

37

• Homozygotes for sickle-cell disease do not
  reproduce heterozygotes have high reproductive
  success and outnumber the homozygotes by 21.
• The normal allele and the sickling allele are
  both kept in the population as long as malaria
  is rampant.

38

• Sickle cell trait (the heterozygous condition)
  occurs in just 4 of Americans of African
  descent.
• The apparently rapid dissipation of the
  sickle-cell trait must be a response to the
  disappearance of malaria.
• This is not to minimize the impact of sickle-cell
  anemia.

39
PTC tasting

• There are many examples of balanced polymorphisms
  in humans.
• One of them is PTC tasting.
• Phenylthiocarbamide chemical close in structure
  to one found in mustard plants, cabbages, and
  Brussel spouts.
• Overeating these plants interferes with thyroid
  function tasting PTC may have an adaptive
  advantage.

40

• We dont know why indigenous populations in
  Siberia are up to 60 tasters, while indigenous
  populations of the Americas have as little as 10
  tasters.

41
Lactase deficiency Lactose intolerance

• Another balanced polymorphism is lactase
  deficiency.
• The enzyme lactase breaks down milk sugar,
  lactose, into simple sugars.
• By the time they are four years old, most humans
  stop secreting lactase and become lactase
  deficient and lactose intolerant.

42

• Drinking unfermented milk then produces a lot of
  discomfort bloating, diarrhea, nausea.
• This trait keeps adults from competing with
  infants for milk, but we do not know if this is
  the adaptive reason for the development of the
  trait.

43

• People who are lactase sufficient consume and
  produce milk and have for a very long time.
• In northern Europe, animal milk was,
  prehistorically, one of the only sources of
  calcium.

44
Out of Africa and lactose tolerance

• Moving out of Africa, people 200,000 years ago
  were probably all lactase deficient.
• Lactose tolerance was probably a associated with
  the movement of pastoral peoples moving into
  northern Europe from the Mediterranean.

45
Recent micro-evolutionary events

• This may have happened just a few thousand years
  ago.
• Lactose, like vitamin D, helps absorption of
  calcium, but only for people who produce lactase.
  
• Continued production of lactase and lighter skin
  are both adaptations to higher latitudes.

46

• Northern Europe was settled by farmers from the
  Mediterranean about 6000 years ago.
• The pastoralists who came from the Mediterranean
  were surely heavily melanic.
• They would have been able to adapt to the cold of
  the northern latitudes culturally by making
  heavy skin clothing and covering themselves from
  head to toe.

47

• This would have been highly selective for white
  skin, especially white faces, so that the
  sunlight could be absorbed and vitamin D could be
  produced.
• Pink cheeks on babies are highly admired among
  white people. Marvin Harris pointed out that this
  preference probably comes from a selective
  advantage.
• The pink in pink cheeks is the sight of blood
  through translucent skin skin that absorbs
  maximally the UV sunlight.

48

• Producing vitamin D is only half the story.
  Vitamin D transports calcium to the cells, so
  people would have needed a good supply of calcium
  in northern climates from milk, for example.
• And this would require that adults be able to
  digest milk.

49

• Lactose intolerant, pastoral peoples use the
  lactobacillus to produce fermented milk products
  like yogurt and cheese (which is more easily
  absorbed) or they separate the lactose-rich whey
  from the curds (and feed the whey to babies).
• But in the northern areas of Europe, there was a
  selective advantage for light skin.

50
Some perspective

• Put lactase deficiency and balanced
  poly-morphisms, like sickle-cell anemia, into
  perspective.
• African Americans have a higher death rate than
  whites in our society, but sickle cell anemia
  accounts for three-tenths of one percent of the
  difference in death rates.
• Most of the difference, for those under 30, is in
  homicide. And most of the difference for those
  over 50 is poorer health.

51
Genes and intelligence

• IQ tests are reliable and predictive, but we
  easily mistake reliability for validity.
• High IQ scores and correlated success scores does
  not mean that intelligence is inherited.

52

• Nationally, whites score about 15 points more, on
  average, than blacks do on IQ tests.
• There is a long series of studies purporting to
  show that this gap is the consequence of genetic
  differences between African Americans and whites.
  
• The idea behind these studies is to use very
  large data sets and control for socioeconomic
  class by controlling for income, education, and
  occupation.

53

• Indicators of socioeconomic class education,
  occupation, and income reflect the systematic
  discrimination that African Americans experience.
  
• We need tests that control for the lack of
  preparation of African Americans in the taking of
  standardized tests and that control for
  neighborhood effects.

54

• The taking of tests is part of a culture of
  achievement.
• This culture may not develop in groups where
  endemic poverty is found.
• This is what we find in groups of Appalachian
  whites and Hispanics who experience economic and
  political discrimination.

55
Why does the race-and-intelligence issue keep
coming up?

• IQ is not intelligence. It is a score on a
  particular test.
• The idea of inherited group intelligence was
  refuted by Boas.
• It was raised again (and knocked down again) in
  the WWI placement tests.

56
Kleinbergs studies

• It was raised again in the 1930s and dismissed by
  Otto Kleinberg's studies
• Black children in New York had higher IQ scores
  than did some white children in the south.
• Length of time in the north accounted for the
  size of the improvement in test scores.

57
Association is not cause

• The false association was championed in the 1970s
  by Jensen and dismissed once again by evidence of
  bias in testing.
• The most recent example of scientific racism was
  the book, The Bell Curve, by Murray and
  Herrnstein in 1994.
• Once again, almost the entire scientific
  community has dismissed the work.

58

• Intelligence is not a single number
• it is not an interval measure
• it is not genetically based in groups
• it is highly malleable in groups and in
  individuals.
• Thirteen low IQ children in Milwaukee were
  adopted by women in a state institution for the
  retarded.
• The childrens scores went from 64 to 101.

59
Flynn effect

• The Flynn effect scores of different generations
  of people in 21 countries have increased by about
  3 points per decade for the last 100 years.
• If IQ tests measured genetically inherited
  intelligence, the children taking the tests today
  would be about 30 more intelligent than their
  great-great-grand parents were.

60

• Cognitive stimulation media after 1950, and
  technological complexity today, including
  computer games.
• More attention and care for children in developed
  countries fewer children and greater wealth.

61
Gender and culture

• From studies done by Carol and Melvin Ember, we
  know that
• Men almost always hunt and trap animals, mine
  and quarry, lumber, engage in combat and make
  boats, musical instruments, and bone, horn, and
  shell objects.
• Men usually fish, herd large animals, collect
  wild honey, clear land, butcher animals, build
  houses, exercise political leadership, and make
  nets and rope.

62
Gender and culture

• Women usually gather wild plants, care for
  children, cook, launder, fetch water, collect
  fuel, spin yarn, and prepare vegetable foods,
  drinks, and dairy products.
• Women almost always care for infants

63
Gender and culture

• Either or both sexes are likely to collect
  shellfish, care for small animals, plant crops,
  tend crops, harvest crops, milk animals, preserve
  meat and fish, prepare skins.
• make leather products, baskets, mats, clothing,
  pottery.

64
Margaret Mead's study of gender roles in New
Guinea

• Tchambuli Women did most subsistence labor, men
  did trading. Women little concern for personal
  adornment men concerned about their personal
  appearance.
• Arapesh men and women acted like the Western
  traditional ideal of women. Shared child care.
• Mundugamor men and women acted like the Western
  traditional ideal of men men hostility and
  distrust even among some close kin.

65
Intracultural variation

• Meads primary observation remains valid
• "Gender roles and sex roles are not the same
  thing."
• Culture plays an important part in determining
  gender roles, within a single generation.
• However, culture does not explain the
  malleability of gender roles across generations
  or across societies.

66
Household work and agriculture

• Household work, particularly for women, increases
  under intensive agriculture. Why?
• 1. Plows are used in intensive agriculture. Upper
  body strength is not limited to men. Economy of
  effort probably shifts the clearing of land to
  men.
• 2. Intensive agriculture is based on grain. Grain
  is dried for storage, making it much more
  difficult and time consuming to prepare and cook.
  
• 3. Women have more children under intensive
  agriculture. This draws them away from
  subsistence activities.

67
Complexity and status

• Societal complexity predicts lower status for
  women.
• Social stratification, irrigation/plow
  agriculture, complex political and economic
  organization and craft specialization ... all are
  associated with lower status for women.