Transcript Science and Evolution

ANG 6930
Proseminar in
Anthropology IIA:
Bioanthropology
Day 2
ANG 6930
Prof. Connie J. Mulligan
Department of Anthropology
This week
Science and Evolution
Reading
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The Human Species, Chpt 1(pp 12-29) and Chpt 4
Course packet
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Park MA. 2005. Biological Anthropology, An Introductory Reader,
Chpt 9 (pp 40-44), Natural Selection (1858), Charles R. Darwin
and Alfred Russel Wallace
Mayr E. 1997. “What is science?” in This is biology: The science of
the living world, pp 24-44. Cambridge: Harvard University Press
Scott EC. 1997. Antievolution and creationism in the United
States. Annual Review of Anthropology 26:263-289
Talbot M. 2005. Darwin in the Dock. The New Yorker, pp 66-77
Berkman MB et al. 2008. Evolution and Creationism in America’s
Classroom: A National Portrait. PLoS Biology, 6:0920-0924
Next week
Genetics and the development of evolutionary theory
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Mendelian and molecular genetics
Population genetics
Evolutionary development biology (Evo Devo)
Reading
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The Human Species, Chpts 2 (Human genetics), 3 (Evolutionary
forces), 8 (Paleoanthropology)
Course packet
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Tattersall I. 2000. Paleoanthropology: The last half-century.
Evolutionary Anthropology 9:2-16
Foley R. 2001. In the shadow of the modern synthesis? Alternative
perspectives on the last fifty years of paleoanthropology. Evolutionary
Anthropology 10:5-14
Carroll SB. 2003. Genetics and the making of Homo sapiens. Nature.
422:849-857
“Beyond Stones and Bones”, Newsweek, March 19, 2007.
Topic and abstract for journal analysis is due
Journal analysis
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Your topic (the relevant question(s) and which other
subfield you will be examining) and an abstract (<200
words) including your search strategy (which journals
are you using and why) is due at the beginning of class
on Jan 21.
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In your abstract, describe the problem you are addressing and
some of the history of this issue. Be sure to specify your two
additional journals, and why you chose them, as well as the
other subfield of anthropology that you will be studying. I
encourage you to discuss your topic with me in advance, in
person or by email.
The final paper is due at our last class, Feb 18.
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Turn in your original (graded) abstract with the final paper
From last week
Current hot topics on humans
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Top 10 mysteries about humans
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http://www.livescience.com/history/091026-top10origins-mysteries.html
Top 10 things that make humans special
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http://www.livescience.com/culture/091030origins-top10-special.html
Anthropology
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Important to remember that a strength of anthropology is
its holistic approach
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What’s the difference between cultural anthropology and
sociology?
What’s the difference between biological anthropology and
biology?
Holistic view is not limited to the 4 anthropology subfields,
but any relevant field
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Many Anthro departments are splitting along subfield lines
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Why do you think more anthropological
research is not truly interdisciplinary?
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How could you make your research relevant to
someone outside your subfield?
Balaresque et al. 2007
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Demography
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Migration/colonization
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Population origins
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Semitic speakers
Admixture
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Out of Africa
Peopling of New World
Puerto Ricans
Adaptation
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Peopling of
the
Americas
Expansion out of Africa
Natural selection
 Skin color
Agriculture/domestication
Disease
 Origin/intro to naïve pop’s
 Genetic/cultural risk factors
Domestication
of the donkey
Modified from Balaresque et al. 2007
Origin and
expansion of
Semitic speakers
Genetic and cultural
components to
ethnicity and health
Chpt 1 - Science and Evolution
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Development of evolutionary thought
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Darwin and natural selection
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Misconceptions about evolution
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Science as a way of knowing
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Science, evolution, and creationism
Landmarks in Euro-American Thought about Human
Origins and Diversity
Age of European
Exploration
Years A.D.
Darwin publishes On
the Origin of Species
Development of Evolutionary
Thought
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Ancient roots – differences and origins
Renaissance – empiricism and science
17th-18th centuries – naturalism
1800-1859 – Racial origins
1859-1900 – Evolution and racial origins
1900-1950 – Description and classification
1950-present – New Physical Anthropology
Pre-Darwinian Theories
and Seeds of (R)evolution
Pre-Darwinian thought
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Ancient Greek philosophy
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Aristotle (384-322 B.C.)
Greek philosopher and naturalist
Historia Animalium describes similarities between man,
apes, and monkeys
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Static, unchanging view of the world
Differences attributed to position in the scala naturae (Great
Chain of Being)
Aristotle’s notion of scala naturae did not incorporate
racial hierarchy
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Argued for environmental causes of variation
 Wooly hair of Africans due to harsh, arid climate
 Straight hair of Thracians and Scythians due to moist air
Carolus Linneaus (1707-1778)
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Swedish botanist and
founder of taxonomy
Epitomized focus on
description and classification
Systema Naturae (17351766)
Identified two-dimensional
structure of nature, as
opposed to one-dimensional
“Great Chain”
Great Chain vs Linnaean Taxonomy
Source: Marks (1995) Human Biodiversity
Linnaeus’s Classification of Humans
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Homo sapiens in order
Primates
Four geographic varieties
mix culture and biology
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H. sapiens europaeus
H. sapiens asiaticus
H. sapiens americanus
H. sapiens afer
George Louis Leclerc, Comte de
Buffon (1707-1788)
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French naturalist
Opposed Linnaeus
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No unit higher than species
Species comprise Great Chain
of Being
Dismissed evolutionary
implications of Linnaean ideas
Posited microevolution in
response to environment,
but denied macroevolution
Buffon and Human Variation
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Buffon rejected classification as goal of study,
aimed to describe and explain diversity
Varieties of the Human Species (1749)
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How is variation patterned?
What explains patterns of variation?
Buffon and Linneaus represent two strains of
thought in 20th century anthropology
Georges Cuvier (1769-1832)
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French zoologist and
founder of paleontology
Embraced Linnaeus’s
nested hierarchy, but not
evolutionary implications
Best remembered for
catastrophism
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Mass extinctions, repopulation
gives appearance of change
Consistent with Biblical view
Jean Baptiste, Chevalier of Lamarck
(1744-1829)
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French aristocrat
Regarded classification as
sterile and theorized about
process of evolutionary change
Inheritance of acquired
characteristics
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Organism altered during lifetime
by environment and behavior
Change inherited by offspring
James Hutton (1726-1797)
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Scottish geologist
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Developed principle of
uniformitarianism (1785)
 Same geologic processes
(erosion, continental drift) operate
today as in the past
 Earth has long history
 Supernatural theories not
required to explain history
 Earth’s geology shaped by
processes observable today
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e.g. Deep soils formed by the
weathering of bedrock over 1000s
of years
Sir Charles Lyell (1797-1875)
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Scottish geologist
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Promoted and extended
principle of
uniformitarianism
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Three-volume Principles
of Geology (1830-1833)
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Darwin – “I always feel
as if my books came half
out of Lyell’s brain.”
Charles Darwin (1809-1882)
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Born into intellectual
family in northern England
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Enrolled in medicine, then
graduated in theology
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Joined HMS Beagle in
1831 as “unpaid
gentleman scholar and
naturalist”
Voyage of the HMS Beagle
Darwin and Wallace
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Darwin outlined theory of
natural selection in 1837
20 years later, young Wallace
developed same theory
Darwin and Wallace copresented at Linnaean Society
of London (1858)
Darwin published On the
Origin of Species a year later
Alfred Wallace
1823-1913
Darwin’s observations
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Much morphological variation
Variation made sense in terms of
environment
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Creatures in cold climates had fur
Birds in areas where insects live deep inside tree
trunks have long beaks
Darwin’s Postulates
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Infinite ability of populations to grow, but finite ability
of environments to support growth
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Malthus showed that the planet can not support
uncontrolled growth, i.e. a large percentage of offspring will
die and Darwin helps provide the answer as to who will die
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Within populations, organisms vary in ways that
affect ability to survive and reproduce
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Variations are transmitted from parents to offspring
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Natural selection – evolution by variation and
selective retention
An Example – Darwin’s Finches
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Darwin identified multiple species of finches
on Galápagos Islands, attributed special role
in his thinking
Drought and Darwin’s Finches
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Natural experiment–
severe drought—tests
Darwin’s postulates
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As food supply shrank,
finch population declined
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Beak depth affected
survival
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Parents and offspring
had similar beak depths
Darwin’s Finches
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Directional selection
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Beak depth influences individual’s probability of survival
Distribution of beak depth shifts to right due to selection
Darwin’s Finches
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Balancing selection
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Selection maintains status quo when most common type is
best adapted
Selection required to keep populations the same, not just to
change
Individual Selection
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Selection arises from competition among
individuals, not among populations or species
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Example – individual reproductive success vs
species’ survival
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Selection may favor high individual fertility,
even if population growth threatens survival
of species
Evolution of Complex Adaptations
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Small variations are important
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Continuous, not discontinuous traits important
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Complexity arises from accumulation of small random
variations
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Typing monkeys - “Methinks it is like a weasel.”
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Chance of randomly typing monkeys reproducing
Shakespeare - ~ 1 in a trillion. Same as chance of randomly
producing a human eye in a single trial
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Convergence - complex adaptations have evolved
independently multiple times
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Selection favors intermediate phenotypes
Selection of Intermediate Steps
Living gastropod mollusks illustrate intermediate steps
between eye cup and camera-type eye
Rates of Evolutionary Change
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14 living species in
Galápagos
All descended from
single species within
last half million years
Evolution of Evolutionary Theory
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Darwin could not explain how variation was
maintained
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Assumed blending inheritance
Could not explain evolution beyond original range
of variation
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Acceptance of Darwinian mechanisms
awaited rediscovery of Mendelian genetics
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Modern Synthesis (1930-1950)
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Evo-Devo (1980-present)
Science and
Creationism
What is Science?
[Empirical science] is systematic description and
classification of objects, events, [and] processes, and the
explanation of those events and processes by theories
that employ lawful regularities, all of the descriptive and
explanatory statements employed being testable against
publicly observable data.
O’Meara, 1989
Science Is…
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Empirical
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Systematic and explicit
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Theoretical, explanatory, predictive
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Self-critical, reflexive, based on testing
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Public
Creationist Claims
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“Evolution is only a theory”
Actually, evolution is both a fact and a theory
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Fact is “an observation that has been repeatedly
confirmed and for all practical purposes is
accepted as ‘true.’”
Theory is “a well-substantiated explanation of
some aspect of the natural world that can
incorporate facts, laws, inferences, and tested
hypotheses.”
National Academy of Sciences
Creationist Claims
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“Evolution is unscientific, because it is not
testable or falsifiable.”
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Microevolution and macroevolution
Fossil record and macroevolutionary hypotheses
“Living things must be products of intelligent
design, because natural selection could not
produce some complex beings.”
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Evolution of camera-type eye
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Convergence
Chpt 4 - Speciation
and Phylogeny
Overview
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Microevolution  macroevolution
Species concepts
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Biological species
Ecological species
Evolutionary forces
Systematics, phylogeny, and taxonomy
Definitions
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Microevolution
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Changes in allele frequencies over relatively short time
periods/small geographic ranges/small genomic ranges
Evolution over short time periods
Occurs in our lifetime, i.e. is observable to all of us
Macroevolution
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Changes in allele frequencies over relatively long time
periods/large geographic ranges/large genomic ranges
Evolution over long time periods
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Creationists have problem with macroevolution b/c they say
we can’t directly observe macroevolution
We can’t do million year experiments, but we can make
testable predictions, like in geology or astronomy
What Are Species?
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Species are real biological categories, not abstractions
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Controversy about how species are defined
Biological species concept
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Paleospecies are more abstract concepts
Group of organisms that naturally interbreed and produce fertile
offspring
Ecological species concept
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Natural selection plays important role in species differences
Reproductive isolation not necessary
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Species occupy different ecological niches, but are not necessarily
physically isolated from each other
Phylogenetic species concept
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Some level of genetic variation is chosen to define different
species
Modes of Speciation
Anagenesis
Cladogenesis
Phylogeny and Systematics
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Phylogeny refers to evolutionary
relationships among group of
species, often depicted as a
“family tree”
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What is the “outgroup” in this tree?
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Systematics is construction of
phylogenies
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Taxonomy is use of phylogenies
in naming and classification
Approaches to systematics
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Evolutionary systematics
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Considers all homologous traits, primitive and derived
Based on descent and overall similarity
Complex algorithms to evaluate genetic distance or
coalescence and translate that relationship into a tree
Cladistics
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Argues that phylogenies should be constructed only on
shared derived traits
Much simpler, less sophisticated and probably less
realistic
Natural selection
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Mechanism for evolutionary change favoring
the survival and reproduction of some
organisms over others because of their
biological characteristics.
Requirements:
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Variation must exist a priori in order for natural
selection to act, i.e. natural selection does not
create a variant but it ‘prefers’ it
Preferred variant/phenotype must act in such a
way as to influence fitness of offspring, i.e.
Alzheimer’s will not be selected against b/c it
occurs late in life long after childbearing years
Misconceptions of evolution and
natural selection
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Bigger is better
Newer is better
Faster is better
Natural selection always works
Evolution has a direction or goal
Natural selection always produces perfect structures
All structures are adaptive
Current structure reflect initial adaptations
Natural selection will solve every problem – Will
natural selection solve problem of stress-based
disease?
What is evolution?
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From a genetic perspective, not phenotypic
At the most basic, causative definition
What is evolution?
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Changes in allele frequencies over time
What are the evolutionary forces
that can change allele
frequencies over time?
What are the evolutionary forces
that can change allele
frequencies over time?
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Mutation
Natural selection
Genetic drift
Gene flow
What are the evolutionary forces that can
change allele frequencies over time?
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Mutation
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Introduces a new variant, initially at very low frequency
Natural selection
Genetic drift
Gene flow
What are the evolutionary forces that can
change allele frequencies over time?
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Mutation
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Natural selection
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Introduces a new variant, initially at very low frequency
Alleles that increase fitness exhibit an increase in freq
Alleles that decrease fitness exhibit a decrease in freq
Balancing selection/heterozygote advantage = heterogzygote has
selective advantage so frequencies of both alleles are selected to be
in balance (sickle cell allele of hemoglobin protein)
Genetic drift
Gene flow
What are the evolutionary forces that can
change allele frequencies over time?
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Mutation
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Natural selection
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Alleles that increase fitness exhibit an increase in freq
Alleles that decrease fitness exhibit a decrease in freq
Balancing selection/heterozygote advantage = heterogzygote has
selective advantage so frequencies of both alleles are selected to be
in balance (sickle cell allele of hemoglobin protein)
Genetic drift
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Introduces a new variant, initially at very low frequency
Random change in allele frequency from generation to generation
Gene flow
What are the evolutionary forces that can
change allele frequencies over time?
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Mutation
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Natural selection
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Alleles that increase fitness exhibit an increase in freq
Alleles that decrease fitness exhibit a decrease in freq
Balancing selection/heterozygote advantage = heterogzygote has selective
advantage so frequencies of both alleles are selected to be in balance (sickle cell
allele of hemoglobin protein)
Genetic drift
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Introduces a new variant, initially at very low frequency
Random change in allele frequency from generation to generation
Gene flow
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One individual moves into a new population and reproduces there
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New genes are introduced into a population
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Gene flow makes 2 populations more similar
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No gene flow → reproductive isolation → genetic divergence → speciation
What are the evolutionary forces that can
change allele frequencies over time?
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Mutation
Natural selection
Genetic drift
Gene flow
In reality, all 4 forces, or a subset, can act at the
same time
Bioethics
Review of research involving
human subjects
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Federal regulations require that all research involving human subjects be
approved by an IRB prior to the research
Institutional review board = IRB
Virtually all universities and research institutes will have their own IRBs
 Composed of professors/scientists who volunteer their time
Must be research – anything commercial is not subject to same
regulations, e.g. if someone pays to have genetic typing performed or
forensic case work or contract archaeology
Also excludes general medical practice, i.e. distinction between accepted
and experimental therapy
What is a human subject?
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A human subject is a living individual about whom
a researcher obtains:
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Data through intervention or interaction w/ the individual
Identifiable private information
IRB regulations do not cover:
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Dead persons – no protection for the sample of
someone who has died
Samples that are already collected and that have no
identifying information (i.e. are anonymous)
Goal of IRB review
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To safeguard the rights and welfare of human subjects
participating in biomedical and behavioral research
Guided by the Belmont Report
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The Belmont Report
Ethical Principles and Guidelines for the Protection of Human
Subjects of Research
The National Commission for the Protection of Human Subjects of
Biomedical and Behavioral Research
April 18, 1979
Written in response to past abuses of human subjects in
biomedical research
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WWII
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Abuses of concentration camp victims
Tuskogee Syphilis Project
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Gov’t sponsored study (1932-1972) that denied effective treatment for
syphilis to 399 African-American men in order to document the natural
history of the disease
Three basic principles
Belmont Report
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Respect for persons
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Subjects must be given the opportunity to choose what will or will
not happen to them
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Beneficence
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Principle of informed consent and the consent process (information,
comprehension and voluntariness)
“do no harm”
“maximize possible benefits and minimize possible harms”
Extends to both investigator and society
Justice
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Requires that there be fair procedures and outcomes in the
selection or subjects, both individually and socially (no one asked
to unfairly bear burdens)
Projects in which the study populations
are intimately involved with the project
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Iceland – National human genome project
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deCode Genetics, an Icelandic start-up genomics
company, spearheaded a project to map the genome of
the Icelandic people as part of a larger medical
database
African Ancestry project
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Provides DNA testing to determine indigenous African
paternal and maternal lineages among African
Americans
deCode Genetics
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Iceland is ideal location for a genetic disease association study
 Historically small population (~50,000 19th century & ~275,000 today)
 Relatively homogeneous and comparatively isolated
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Disease candidate genes may be easier to identify
Detailed genealogical records for generations
Detailed medical records dating back to 1915
In 1998 Icelandic parliament passed a bill authorizing the construction of
a national medical database
Lots of controversy, some detractors, but general Icelandic public seems
to be in favor of project
 Informed consent as far as medical records goes was based on the
principle of presumed, rather than informed, consent, i.e. people had to
specifically request that their medical records not be used
Many papers have identified genes involved in schizophrenia, heart
attacks, asthma, pain, vascular disease, diabetes, etc
African Ancestry project
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Motivated by African-Americans’
desire for more information about
their ancestry
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There is only limited historical info
available for African-Americans prior
to their enslavement
From 1619-1850, millions of
indigenous west and central Africans
were enslaved
Primarily from Senegal south through
the Cape of Good Hope and north
along eastern Africa to Cape Delgado
African Ancestry project, cont
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Spurred by African Burial Ground project
In 1991, human remains were uncovered from an 18th
century burial ground of enslaved African in lower
Manhattan
African American community became a major contributor
(both financial and intellectual) to a research project with
these aims:
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What are the origins of the population?
What was the physical quality of life in 18th century NYC?
What can the site reveal about the biological and cultural transition
from African to African American identities?
My experiences
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Panama
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Explaining my research to indigenous groups in Panama
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Genetics is my way of understanding history
Collecting trip in Panama w/ Panamanian colleague
Different decision-making process
How to inform an indigenous person about my research?
Yemen and Mongolia
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Different experience – completely positive and enthusiastic
Bottom line
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Best research involves research subjects from the
beginning and throughout project
Best research honors the beliefs and goals of the
research subjects
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Don’t expect them to buy into “greater good” argument
because that is a standard of our culture, not all cultures
Best research assumes that research subjects can
be educated about the research as long as you put
yourself in their position
Discussion questions
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Scientists and the general public
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Do scientists/the general public have a “right” to
learn about the human past?
Do scientists/the general public have a
“responsibility” to learn about the human past?
Individuals
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Do individuals have a “responsibility” to participate in
research for the common good?
Do individuals have a “right” to participate in
research for the common good?