ANG 6930 Proseminar in Anthropology IIA: Bioanthropology

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ANG 6930Proseminar in Anthropology IIA
Bioanthropology

• Day 6
• ANG 6930
• Prof. Connie J. Mulligan
• Department of Anthropology

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New research in last weeks Science

• Out of Africa
• Did Modern Humans Travel Out of Africa Via
  Arabia? A German-led team argues on page 453 of
  this week's issue of Science that tools found
  under a rock overhang in Jebel Faya, United Arab
  Emirates, were made by modern humans who may have
  crossed directly from Africa as part of a
  migration spreading across Europe, Asia, and
  Australia. http//www.sciencemag.org/cgi/content/
  summary/331/6016/387
• The Southern Route "Out of Africa" Evidence for
  an Early Expansion of Modern Humans into Arabia
  S. J. Armitage et al. Artifacts in eastern
  Arabia dating to 100,000 years ago imply that
  modern humans left Africa early, as climate
  fluctuated. http//www.sciencemag.org/cgi/content
  /abstract/331/6016/453
• Stone tools found in UAE date to 125kya and are
  similar to E African tools
• Pushes back exit of AMHS from Africa by tens of
  thousands of years
• Weak link are tools truly E African, or could
  they be Neanderthal and not evidence of an
  earlier exit by AMHS?
• What do the molecular data say?

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This week

• Origin of modern humans/Human biodiversity and
  race
• Homo floresiensis
• Anatomically modern Homo sapiens
• African replacement or multiregional evolution?
• Global patterns of human genetic variation
• Anthropological critique of race
• Reading
• The Human Species, Chpts 13 (Origins of modern
  humans), 14 (Human variation)
• Course packet
• Tattersall I. 2009. Human origins Out of Africa.
  Proceedings of the National Academy of Sciences
  10616018-16021.
• Powledge TM. 2006. What is the Hobbit? PLoS
  Biology. 42186-2189.
• Scheinfeldt L et al. 2010. Working toward a
  synthesis of archaeological, linguistic, and
  genetic data for inferring African population
  history. Proceedings of the National Academy of
  Sciences 1078931-8938.
• Serre D and Pääbo S. 2004. Evidence for gradients
  of human genetic diversity within and among
  continents. Genome Research 141679-1685.
• Haak W. 2008. Ancient DNA, strontium isotopes,
  and osteological analyses shed light on social
  and kinship organization of the Later Stone Age.
  PNAS. 10518226-18231.
• On the origin of art and symbolism Science
  2009, 323709-711.

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Next week (last week!)

• Evolution of human life history and intelligence
• Textbooks
• Population history, Natural selection and
  adaptation, Agriculture and civilization
• Coursepack
• Reproduction and fertility, Human growth and
  development, Aging and senescence, Primate
  intelligence, Social behavior, Evolution of
  language
• Reading
• The Human Species, Chpts 15 (Recent
  microevolution in human populations), 16 (Human
  adaptation), 17 (Biological impact of agriculture
  and civilization)
• Course packet
• Are humans still evolving? Science 2005,
  309234-237.
• Gravlee CC et al. 2009. Genetic ancestry, social
  classification, and racial inequalities in blood
  pressure in southeastern Puerto Rico, Public
  Library of Science ONE 4e6821.
• Dental evidence suggests Neanderthals matured
  faster than we do Science 2007.
• Hawkes K. 2004. Human longevity The grandmother
  effect. Nature 428128-129.
• Lähderpera M, Lummaa V, Helle S, Tremblay M,
  Russell AF. 2004. Fitness benefits of prolonged
  post-reproductive lifespan in women. Nature
  428178-181.
• Finch CE. 2010. Evolution of the human lifespan
  and diseases of aging Roles of infection,
  inflammation, and nutrition. Proceedings of the
  National Academy of Sciences.
• Civilizations cost The decline and fall of
  human health Science 2009. 324588.
• Herrman E et al. 2007. Humans have evolved
  specialized skills of social cognition The
  cultural intelligence hypothesis. Science
  3171360-1366.
• Nonhuman primates demonstrate humanlike
  reasoning Science 2007, 3171308.
• Journal analysis due, take-home exam handed out
  and due next week

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Origin of Modern Humans
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Overview

• Morphology and fossil record of anatomically
  modern humans
• Evolution of human behavior
• Upper Paleolithic technology and culture
• Revolution or evolution?
• Modern human origins debate
• Genetic data
• Fossil record

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The big picture
Evidence of modern human behavior in Europe and
Australia
Archaic populations evolving to anatomically
modern H. sapiens
Only modern H. sapiens in fossil record
Likely migrations from Africa

Years BP
10,000
20,000
30,000
40,000
50,000
60,000
70,000
80,000
90,000
100,000
110,000
120,000
130,000
140,000
150,000
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Evolutionary trends from hominid to human

• What are some of the characteristics that evolved
  to make us uniquely human?

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Evolutionary trends from hominid to human

• What are some of the characteristics that evolved
  to make us uniquely human?
• Bipedalism - 4 mill yrs ago
• Ardipithecus ramidus (oldest hominid) and
  Australopithecus anamensis
• Smaller teeth (change in diet) - 3 mill yrs ago
• Australopithecus afarensis (Lucy)
• Reduction in robustness - 2.5 3 mill yrs ago
• Australopithecus africanus or A. garhi
• ? in brain size - 2 2.5 mill yrs ago
• H. erectus
• Art (symbolic expression) 40,000 yrs ago
• H. sapiens

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Morphology of modern H. sapiens

• Small face with protruding chin
• Rounded skull
• High vaulted cranium
• Vertical forehead, no supraorbital torus
• No occipital bun or torus
• Less robust postcranial skeleton
• Longer limbs with thinner-walled bones
• More lightly built hands
• More narrow pelvis, shoulders

Cro-Magnon 1 30 ka Discovered 1868
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• Archaic humans on left
• Low cranial vault, large brow ridge, robust
  (large) face
• Modern humans on right
• High cranial vault, vertical forehead, prominent
  chin, less robust (smaller) face
• But, right (a) has a robust face and large brow
  ridges and right (c) has a sloping forehead, a
  larger face and large brow ridges.
• ? much morphological variation b/t archaic and
  modern

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Fossil record of modern H. sapiens
Jurmain et al.
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Early modern Homo sapiens in Africa and Near East
Site Dates Dating Method Human Remains
Qafzeh (Israel) 90 ka Electron spin resonance ?20 individuals
Skhul (Israel) 90 ka Electron spin resonance ?10 individuals
Klasies River Mouth (S. Africa) 134-74 ka Electron spin resonance Several individuals highly fragmentary
Herto (Ethiopia) 160-154 ka 40Ar-39Ar 3 adults, one child
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Modern H. Sapiens in Europe, Asia, and Australia
Site Dates Human Remains
Abrigo do Lagar Velho (Portugal) 24.5 ka Four-year-old child
Cro-Magnon (France) 30 ka 8 individuals
Ordos (Mongolia) 50 ka (?) 1 individual
Kow Swamp (Australia) 14-9 ka ? 40 individuals, including adults, juveniles, and infants
Lake Mungo (Australia) ?60-30 ka 3 individuals, including one cremation
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Evolution of modern human behavior

• Early modern humans able to create and transmit
  complex symbolic behavior
• Moderns in W. Eurasia created tool industries
  collectively known as Upper Paleolithic
• 45-10 ka
• Upper Paleolithic peoples
• Technology of first moderns in Australia similar
  to European Upper Paleolithic
• Sparse record in Asia, controversy in Africa

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Complex behavior in Upper Paleolithic

• Ecological range
• Early moderns extended range farther east and
  north than previous hominids
• Inhabited difficult, cold, dry environments
• Technology
• Assembled more sophisticated and standardized
  tools from wider variety of materials
• Constructed elaborate shelters
• Seafaring 100 km of open ocean to Sahul (New
  Guinea, Australia, Tasmania)

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Complex behavior in Upper Paleolithic

• Social organization
• Used raw materials from hundreds of kilometers
  away
• Long-distance trade networks, migrations
• Flint quarried in Poland identified in sites 400
  km away
• Symbolic expression
• Created art, ornamentation
• Performed ritual burials, practiced other
  symbolic behavior

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Upper Paleolithic technology

• Shift from round flakes to blade tools Mode 4
• More time-intensive
• More efficient use of raw materials
• Greater variety
• More specialized tools
• Distinctive designs for tool types
• Increased variation in time and space

1,3,4,5, 7,8,9 points 2 borer 6 scraper
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Upper Paleolithic technology

• UP spanned depths of last ice age
• Cold, dry grasslands, with temperatures to -50?F
• Required improved shelter
• Evidence of multifamily huts
• Clothing
• Bone awls and needles common
• Russian burial site includes caps, shirts, pants,
  shoes
• Fox, wolf remains without feet

Mezherich, Ukraine (15 ka)
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Upper Paleolithic peoples in Europe better
adapted to environment

• Higher population densities than Neandertals
• Increased lifespan
• UP men sometimes reached 60, women rarely reached
  40
• Neandertals rarely reached 40
• Decreased injury and disease
• Relatively scare evidence of traumatic injury
• Slightly more evidence of disease, but less than
  among Neandertals

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Upper Paleolithic symbol and ritual
Hohle Fels (30 ka)
Le Chauvet (30 ka)
Ivory horse fromVogelherd, Germany(30 ka)
Venus of Willendorf(25 ka)
Lascaux (17 ka)
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Human revolution or evolution?

• Human revolution
• Sudden appearance of complex adaptive and
  symbolic behavior in Europe 40 ka
• Klein argues that African archaeological record
  parallels Europe
• Brooks and Yellon argue African record predates
  Europe and shows more gradual change
• A revolution is interpreted as evidence of sudden
  emergence of cognitively modern people
• How plausible is this scenario? How well
  supported is it by the archaeological record?

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Potential objections to revolution

• Natural selection posits complex adaptations by
  accumulation of small changes
• Fossil record and comparative primatology suggest
  continuity in evolution of intelligence
• Punctuated event unlikely
• Archaeological record fundamentally biased in
  favor of Europe
• 10 times as many sites in France alone as in
  entire African continent

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Origins of modern behavior in Africa

• Sally McBrearty and Alison Brooks argue that MSA
  is not equivalent to Middle Paleolithic
• Signatures of modern human behavior gradually
  appear in Africa between 250-50 kya
• Transition from Middle (200kya) to Upper
  (40kya) Paleolithic in Europe should not be
  confused with origins of modern humans

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Origins of modern behavior in Africa

• Blades appear early in MSA (240-280 ka)
• There is regional variation in MSA industries
• Refined bone tools at MSA sites (72 ka)
• MSA peoples transported raw materials over
  hundreds of kilometers
• MSA peoples built stone shelters and hearths
• There is evidence of decorative carving (77 ka),
  beads (50 ka), pigment use (240-280 ka)
• New evidence of engraved ochre pieces 100 ka in S
  Africa (Science, 2009, 323569)
• Appear to be engraving, not just grinding off
  ochre, but who knows if its symbolic

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What is symbolic?The ability to construct
symbols that convey meaningSymbols must have a
commonly understood meaning

• If its a one-off, I dont think it counts. Its
  not sending a message to anyone
• Thomas Wynn, Science, 2009, 323709-711

Cave art, Le Chauvet (30 ka)
Engraved ochre, S Africa (77 ka)
A woman? Berekhat Ram, Israel (250 ka)
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X
Source McBrearty and Brooks (2000) Journal of
Human Evolution 39453-563
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Theories on the origin of modern humans
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Multiregionalism vs replacement theories of human
evolution

• What is multiregionalism?

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Multiregionalism vs replacement theories of human
evolution

• What is multiregionalism (also called regional
  coalescence)?
• Evolution w/i a single lineage spread throughout
  the world/Multiple evolutions of anatomically
  modern humans throughout the world
• Species changed as a whole while retaining
  regional characteristics
• e.g. ? in brain size seen 700,000 years ago,
  worldwide
• Based on continuity of million-year-old fossils
  and younger fossils in multiple regions outside
  of Africa
• e.g. shovel-shaped incisors are more frequent in
  E Asia throughout many periods
• Besides temporal continuity, what could account
  for the supposed similarity through time of
  certain morphological characteristics in the same
  geographic region?
• Dependent on high levels of gene flow to keep us
  all the same species so we can interbreed
• Postulates a global evolution of humans as
  opposed to a geographically restricted one in
  Africa
• All humans over past 2 million yrs are part of
  the same evolutionary lineage

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Multiregionalism vs replacement theories of human
evolution

• What is the replacement theory?

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Multiregionalism vs replacement theories of human
evolution

• What is the replacement theory?
• Homo erectus spread throughout world, 1-2 million
  years ago
• Anatomically modern humans left Africa
  150,000-200,000 years ago and replaced all other
  hominid populations throughout the world
• Depends on archaics and moderns being separate
  species
• Little or no interbreeding b/t modern humans and
  older hominid populations
• What kind of scenarios might explain a lack of
  interbreeding?
• All of our ancestors lived in Africa 200,000 YBP

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Assimilation Model

• Relethfords proposed model
• Also called weak out-of Africa, primary African
  origin model
• Out-of-Africa w/ admixture b/t archaic,
  indigenous pops and modern, invading pops
• Basically an intermediate theory b/t
  out-of-Africa (OOA) and multiregionalism
• Despite what Relethford says, I dont consider
  his theory multiregional evolution b/c its
  simply interbreeding b/t 2 species (or
  subspecies) and not independent evolution of
  modern traits as multiregionalism was originally
  proposed
• An intermediate model is supported by recent
  molecular genetic data indicating some
  interbreeding of AMHS with Neanderthal (possibly)
  and Denisova

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Continuity with no gene flow
Strict Out of Africa(complete replacement)
Debate centers onthis range of admixture
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0
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Percentage of local, archaic admixture in first
modern humans in Eurasia
Adapted from Pearson, O.M. (2004) Evolutionary
Anthropology 13145-159
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Gene trees

• Compare DNA from pairs of living people, build
  tree to track history of particular gene
• Many studies focus on mtDNA
• Maternal inheritance no recombination
• High mutation rate more accurate dating
• High copy rate easier to recover in fossils
• Generally find two clusters African and
  non-African
• Does not falsify multiregional hypothesis

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Genetic diversity

• Greater heterogeneity in African populations
  taken as evidence of antiquity more time to
  accumulate mutations
• Pattern could also be shaped by population size
• Relethford and Jorde 50-70 of ancestors in
  Africa

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Genetic diversity analysis

• First split between African and non-African
  populations
• Indicates African origin
• Same pattern could be produced by slightly more
  gene flow out of African than into Africa
• However, genetic data all show coalescence
  100-200kya not consistent with multiregionalism

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Population size and modern human origins

• Genetic variation in living humans contains
  signature of past population size
• Comparison of contemporary variation with
  simulated populations suggests rapid growth of
  population 50 kya
• Possibly no more than 10,000 adults 200 kya
• Assumptions uncertain actual number may be lower
  if there was a lot of population structure

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Bottom line - Mostly Out of Africa w/ possibility
of non-African admixture
Africa
Europe
Asia
Present
Modernhumans
Time
Archaichumans
Past
Africa
Asia
Europe
Adapted from Relethford (2003)
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Study of human variation
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(No Transcript)
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Anthropology and Race

• History of anthropology tied to history of race
  concept
• Early anthropologists played central role in
  creating racial worldview
• Later, anthropologists played major role in
  dismantling American racial worldview
• Today, anthropologists engage in public education
  about race and human diversity

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Race in early Anthropology

• Racial typology was guiding aim of 19th and early
  20th century anthropology
• Unilinear evolution
• Rank human groups along single evolutionary path
  from savagery to civilization
• Cultural and biological anthropologists
• Biological determinism
• Basic assumption that biology ? culture

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Boasian critique of race

• Statistical averages do not reflect ideal types
• No discrete boundaries
• Significant within-group variation
• Racial types are not fixed
• Heredity and environment
• Plasticity
• Race ? language ? culture

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Boass immigrant study

• Commissioned by U.S. Immigration Commission
• Boas and team of 13 assistants collected data on
  nearly 18,000 people
• Largest data set of family measurements
• Best remembered for critique of cephalic index

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Cephalic Index

• Anders Retzius devised cephalic index and built a
  theory of history on it
• Ratio of head breadth to head length
• Treated as fixed marker of racial phylogeny
• Boass demonstration of change in generation
  undermined typology

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Gravlee, Bernard, Leonard (2003)

• Reanalyzed data Boas published in 1928
• Address three key findings
• Differences between foreign- and U.S.-born
• Increasing influence of environment over time
• Differences between U.S.-born children and
  foreign-born parents

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Rise of No-Race Anthropology

• Cultural and biological anthropologists played a
  key role in challenging race
• Livingstone There are no races, there are only
  clines
• After WWII, no-race position came to mean no
  discussion of race in anthropology

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Race returns to Anthropology

• AAPA (1996) and AAA (1998) released statements on
  race
• Anthropologists advised Census on race
• AAA launched 4 million public education project
• Anthropologists engaged in interdisciplinary
  debate on human variation
• Growing focus on social reality of race and racism

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Health, race, and anthropology

• Substantial disparities in life and death
• Persistence of racial-genetic determinism in
  biomedicine
• Opportunity to advance anthropological critique
  of race

Source National Center for Health Statistics
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Race in medicine today

• Race is ubiquitous in contemporary medical
  research and clinical practice
• Medical education
• Medical students instructed about genetic basis
  of racial disparities in health
• Clinical case presentations cite patients race
• Race is used routinely and uncritically in
  clinical and epidemiologic research

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Racial-genetic determinism

• Williams review of medical dictionaries reveals
  assumption that race is biology
• But explicit definitions of race in medical
  research are rare
• Not one of 121 studies in AJE, 1960-1990, defined
  race
• Race often used as proxy for unspecified
  combination of behavioral, environmental, and
  genetic factors

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Is breast cancer in young Latinas a different
disease?

• Biffl et al. aim to clarify the relationship
  between race/ethnicity and disease severity
• They conclude that young Latinas might have more
  aggressive disease compared with other young
  women
• They do not propose why this difference might
  exist, nor do they define race/ethnicity

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Published commentaries note ambiguity of
race/ethnicity
Note how primitive we are in identifying what
patient sample were talking about.How we
racially profile our patients in these studies is
important.I think in the future, were going to
have to get more sophisticated with identifying
gene pools and not use the color of the patients
skin Dr. Victor J. Zannis
I think its really important that you define
what you mean by Latina because this could mean
Mexican, it could mean Central American, it could
mean Puerto Rican, and I dont think that youre
dealing with a genetically identical gene pool in
the best of circumstances. Dr. Maria D. Allo
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BiDil the first ethnic drug
http//www.nitromed.com/BiDil.shtml
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Critique of race as biology

• Persistence of racial-genetic determinism
  requires clarity in critique of race
• Two fallacies in racial-genetic explanations of
  health
• Population differences in health are genetic in
  origin
• Race is a reliable marker of genetic differences
  between populations

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Fallacy 1 Population differences are genetic in
origin

• Assumption often justified by reference to
  classic racial diseases
• Sickle cell in African Americans
• Tay-Sachs in Ashkenazi Jews
• Cystic fibrosis in Northern Europeans
• But, these disease arent limited to these
  populations, just present at higher frequencies
• These diseases expose weakness of racial model
• Not distributed along racial lines
• Single-gene disorders, not complex phenotypes
  like race
• Complex phenotypes multiple genetic and
  environmental factors

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Fallacy 2 Race is valid marker of genetic
differences

• Most genetic variation among humans occurs within
  populations, not between them
• Variation in gene frequency is distributed
  continuously, or clinally, in response to
  selection or genetic drift
• Human biological variation is discordant traits
  vary independently of one another in response to
  selection or genetic drift

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Why racial classification doesnt work

• Most genetic variation among humans occurs within
  populations, not between them
• Variation in gene frequency is distributed
  continuously, or clinally, in response to
  selection or genetic drift
• Human biological variation is discordant traits
  vary independently of one another in response to
  selection or genetic drift

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Human genetic diversity in comparative perspective

• Most genetic variation among humans occurs within
  populations, not between them
• Not true in other species
• Two humans taken at random are more genetically
  similar than are two chimpanzees taken at random

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Apportionment of human genetic diversity

• Confirmed recently with 377 microsatellite loci
  in 1,056 individuals from 52 worldwide
  populations (Rosenberg et al. 2002)
• Within population variation 93-95
• Between regional groups 3-5

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Why racial classification doesnt work

• Most genetic variation among humans occurs within
  populations, not between them
• Variation in gene frequency is distributed
  continuously, or clinally, in response to
  selection or genetic drift
• Human biological variation is discordant traits
  vary independently of one another in response to
  selection or genetic drift

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• Sampling strategy may create an artifact of
  geographic clusters

Serre, D., and S. Paabo. 2004. Genome Research
141679-1685.
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Variation in skin color in 22 populations
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Clinal distribution of skin color
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Skin color and settlement of U.S.
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Why racial classification doesnt work

• Most genetic variation among humans occurs within
  populations, not between them
• Variation in gene frequency is distributed
  continuously, or clinally, in response to
  selection or genetic drift
• Human biological variation is discordant traits
  vary independently of one another in response to
  selection or genetic drift

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Discordant nature of racial traits

• Race concept assumes that traits are bundled
  together
• Individual traits respond to different forces,
  such as selection or genetic drift
• Unless linked on same chromosome, traits are
  inherited independently

Layers represent 4 traits that vary continuously,
but independently. Each core represents a single
individual and their sampling of each trait
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Global distribution of skin color
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Distribution of blood type A
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Distribution of blood type B
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Overall genetic similarity
Contour map based on sample of 120 genes from 42
populations
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Using current analytic methods and huge DNA
datasets, we can distinguish between populations
in astonishing detail, far beyond races Nothing
magical about racial boundaries, just need
enough markers
A statistical summary of gt ½ million genetic
variants from 1,387 Europeans based on principal
component axis one (PC1) and axis two (PC2).
Small colored labels represent individuals and
large colored points represent median PC1 and PC2
values for each country. PC axes are rotated to
emphasize similarity to the geographic map of
Europe. AL, Albania AT, Austria BA,
Bosnia-Herzegovina BE, Belgium BG, Bulgaria
CH, Switzerland CY, Cyprus CZ, Czech Republic
DE, Germany DK, Denmark ES, Spain FI, Finland
FR, France GB, United Kingdom GR, Greece HR,
Croatia HU, Hungary IE, Ireland IT, Italy KS,
Kosovo LV, Latvia MK, Macedonia NO, Norway
NL, Netherlands PL, Poland PT, Portugal RO,
Romania RS, Serbia and Montenegro RU, Russia,
Sct, Scotland SE, Sweden SI, Slovenia SK,
Slovakia TR, Turkey UA, Ukraine YG,
Yugoslavia. (Novembre et al. Nature, 2008)
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So what do we do with race?

• Biological evidence suggests that race is not a
  useful way to describe biological variation
• Some propose that we should jettison race
• Others note that race is a pervasive social fact,
  even if it is a dubious biological one
• View race as a culture-bound emic construct in
  cross-cultural perspective

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Discussion