ANTH105 Quiz 1
What is Anthropology?
Anthropology is the broad study of humankind around the world and throughout time.
It is also concerned with both the biological and the cultural aspects of humans.
Anthropology is the study of humans– their origins, biological characteristics, cultural development, social relationships, and more– based in scientific methods
The four main subdivisions of Anthropology
Physical/Biological Anthropology
Archeology
Cultural Anthropology- The material aspects of society, the norms and values shared among people, transmitted and learned
Linguistic Anthropology- The study of language and how it varies across different societies
Fifth field: Applied Anthropology- Taking anthropology and applying it to the real world
Physical/Biological Anthropology
How the human species has changed physically over time (hundreds of millions of years)
Biological evolution
Subfields:
Primatology- the study of primates
Genetic inheritance- how physical characteristics are transmitted and evolving over time
Paleoanthropology- researching our human ancestors and looking at the fossil evidence for human evolution
Human biology- modern human health and disease
Bioarchaeology- human culture through human remains
Human behavioral ecology- how humans adapt to their local environment, mainly focusing on the physical environment
What is evolution?
Evolution is the change in inherited characteristics of biological populations over successive generations.
It is also the change in the genetic structure of a population
Evolution is NOT-
Moving toward some sense of perfection
Consistent
Definitions
Adaptation- a feature of an organism created by the process of natural selection.
Adaptive trait- a heritable trait that increases the probability of survival and/or reproduction in a given environment.
An adaptive trait in one population may be maladaptive in another.
Examples: thick fur, colored fur, altered eyesight
The History of Evolutionary Theory
Pre-Darwin thought
Species are fixed and unchanging
Aristotle (300ish BC): the Great Chain of Being
Unchangeable
Linnaeus (1700s)
Father of modern taxonomy
Binomial nomenclature (Homo sapiens)
Fixity of species
James Hutton (1700s)
Father of modern geology
Uniformitarianism/gradualism- Earth changes very slowly over time
Influenced Darwin’s ideas
Jean Baptiste-Lamark (1744-1829)
Simple to complex evolution
Coined the term evolution- change over time
Main ideas
Animals inherit traits from previous generations
Change happens over time
Change has something to do with the environment
“Acquired traits”
Law of use/disuse
Thomas Malthus (1766-1834)
Studied population dynamics
Populations struggle when resources are limited
George Cuvier (1769-1832)
Paleontologist
Fossils can be used to assess time for life on Earth
Catastrophism- when animals go extinct, mass extinctions
Erasmus Darwin (1731-1802)
Charles Darwin’s grandfather
A proponent of the theory that species change over time
Alfred Russel Wallace (1823-1913)
Came up with the theory of natural selection independent of Darwin
Charles Lyell (1797-1875)
Geologist
Earth is changing
Earth changes gradually and in uniformed and predictable processes
Paving the way for Darwin
Theorists who cast doubt on Divine Creation
Georges Cuvier
Charles Lyell
Erasmus Darwin
Contributing to the theory of natural selection
James Hutton
Jean-Baptists Lamarck
Thomas Malthus
Alfred Russel Wallace
Charles Darwin
Medical student
Interest in natural history
Meant to become an Anglican parson
Invited to be on the voyage of the HMS Beagle
Allowed him to take extensive notes and learn about fossils and marine creatures
Served as a companion to the captain
Poor health
Published 3 geological books within 6 years
1858: began writing On the Origin of Species
Darwin and Wallace
Alfred Russel Wallace
Wrote “On the Law which has Regulated the Introduction of New Species”
Darwin quickly wrote a short paper explaining natural selection
Later published On the Origin of Species
Nearly died
Darwin’s contribution: the mechanism- how the change happens
Eastern Evolutionary Thought
People in the Middle East had ideas on evolution before Darwin
Al-Jahiz, Iraq, (776-868 CE)
Ibn Miskawayh, Persia, (930-1030)
Nasir ad-Din Tusi, Persia, (1201-1274)
Ibn Khaldun, North Africa, (1322)
Darwin’s Postulates
There is a struggle for existence.
There is variation in features related to survival and reproduction.
This variation is passed from generation to generation (or from parent to offspring).
These three postulates make evolution by means of natural selection inevitable
Survival of the Fittest?
Survival of the fit enough.
NOT coined by Charles Darwin
Social Darwinism at its worst
More definitions
Fitness- An individual’s genetic representation in future generations
Social Darwinism
“Survival of the fittest” applied to:
Eugenics (Margaret Sanger)
Racism
Francis Galton
Darwin’s cousin
An Example of Adaptation by Natural Selection
Galapagos Islands, Ecuador
Darwin’s finches
Peter and Rosemary Grant, Princeton
Postulate 1: struggle for existence
1200 birds reduced to 180
Postulate 2: variation
Beak depth varied
Influenced survival
Postulate 3: heritable
Beak depth passed from parent to offspring
Darwin’s Difficulties Explaining Variation
Questions?
Blending inheritance?
How is variation maintained if natural selection eliminates it?
Where do novel forms come from if not already present in the original population?
Natural selection produces variation.
Darwin thought that offspring were the blend of two parents. He was very wrong.
Issues with Darwin’s Theory
Blending inheritance could not work.
It would cause a reduction in the variation of traits over time.
Gregor Mendel
Monk
Discovered laws of inheritance
Bred garden pea plants
Worked with traits with two variants
Mendelian Genetics
Crossbreeding experiments
Independent assortment
Each of these particles is equally likely to be transmitted from eggs and sperm
Mendel’s work was “rediscovered” in early 1900s.
Chromosomes discovered
Chromosomes are the small living structures in cells that divide and replicate
Gene
Different versions are “alleles”
If alleles are the same: homozygous
If alleles are different: heterozygous
Genotype
Alleles carried by organism
Phenotype
Observable characteristics
Dominant
Recessive
Modern Synthesis: Key Concepts
Natural selection operates on the phenotype, not the genotype.
Natural selection can change gene frequencies in a population.
Mechanisms of Evolutionary Change
Natural selection results in genetic adaptation.
Genetic drift- random changes
Gene flow- exchange of genetic info between populations
Mutation- alters the bases in the DNA molecule, happens by chance
Types of Adaptation
Acclimatization- response to environmental pressures
Developmental- occurs during development
Behavioural- learned adaptations to environment
Psychological- a mental change to better navigate the world
Are we still evolving?
It is a never-ending process.
Our environment is still changing.
Evolution doesn’t care about health. It maximizes reproduction.
Human Evolution
200,000 YA- the first humans appeared
60,000-40,000 YA “The Great Leap Forward”
10,000-now- from hunter-gather to frustrated commuter
Sociobiology
E. O. Wilson: “Genetic leash”
Sociobiology
Differential reproductive success shapes the evolution of social behaviors of ALL organisms
Genetic determinism: driven by genes
Humans were “vehicles” that genes used to reproduce themselves
E. O. Wilson and Richard Dawkins
Sociobiology: The New Synthesis by Wilson
Selfish Gene by Dawkins
How does one explain altruism?
Critiques of Sociobiology
Ignored culture and learning
The research was conducted on animals and plants, not humans
Assumed specific human behaviors could be linked to genes
Modern Approaches to Evolution and Human Behaviour
Human behavioral ecology
The study of the adaptive nature of human behavior
Mating, parenting, division of labor, cooperation
HBE examines how environmental and ecology factors influence human behaviour
How do we measure reproductive benefits?
Counting babies: not feasible
What about culture?
Evolutionary Psychology
The study of human adaptation from a psychological perspective
Reproductive success, genetics, phonetics adaptation
EEA- the environment of evolutionary adaptiveness
Pleistocene prior to cultural revolution
Environmental mismatch
The aim is to identify the selection pressures that shape the human psyche in our evolutionary history
Repeatedly encountered problems
The human brain - like any other organ - is comprised of specialized “domain-specific” modules that cope with a range of adaptive problems
W.E.I.R.D.
Pencil and paper methods: data is almost entirely self-report with a small sample of modern humans
Gene-culture coevolution/Cultural evolution
Anthropology and Evolution
The first anthropologists of the late 1800s utilized evolution but not Darwin's principles (natural selection)
Unilineal evolution- cultures change over time
Continuous change toward “perfection”
Herbert Spencer
Interested in evolution as a general phenomenon
It has little to do with variation and reproduction
Focused on Lamarkian concepts of evolution
Ignored natural selection
Henry Morgan (1818-1881) and Sir Edward Burnett Tylor (1832-1917)
Unilineal evolutionists
Morgan:
Savagery
Barbaris
Civilization
Tylor:
Animism
Polytheism
“Enlightened” monotheism
Ethnocentric- belief that your culture is superior to others
Cultural relativism- observing a culture in its own light (nonjudgemental)
Leslie White (1943)
Cultural evolution leads to increased complexity
Developed a non-ethnocentric way to measure cultural evolution
Culture advances as “the amount of energy per capita increases”
Julian Steward (1902-1972)
Environment impacts human behavior
Multilinear evolution: culture can evolve in any number of distinct patterns depending on environmental circumstances
Key concepts:
Phenotypic flexibility- changing behavior to match the environment
Environmental conditions include: ecological dimensions, cognitive, social, and political
Intrinsic constraints are particular to the organism, such as physiological limitations
Height, dietary restrictions, allergies, reading level, mobility
Extrinsic constraints are due to the environment (man-made or not)
Famine, drought, food desert, flooding, prices, deforestation
Overview
Microevolution: changes within a species
Macroevolution: the process of how new species evolve
Ligers
What is a species?
Biological Species Concept
Species: life can be clustered into distinct types where the individuals can produce fertile offspring
Ernst Mayr
However, species are difficult to define
Often they do not follow the “rules”
Liges!
Liligers?
Biological species concept: a group of organisms that interbreed in nature and are reproductively isolated
Gene flow: members of the same species share genes
Offspring are infertile
The Ecological Species Concept
Reproductive isolation is not necessary
Natural selection keeps species distinct from one another
Intermediate cannot survive because of selection pressures
Support:
Almost half of all species are not reproductively isolated
Some species have little to no gene flow
Both reproductive isolation and natural selection are important
Offspring don’t survive
The Origin of Species
Three types:
Allopatric
Parapatric
Sympatric
Allopatric Speciation
Geographic isolation
Combination of reproductive isolation and natural selection
Reinforcement: mating behaviors may evolve differences, which ultimately leads to reproductive isolation
Don’t recognize each other as mates
Parapatric Speciation
“Next-door neighbors”
Distinct species with hybrid zones
Natural selection + partial reproductive isolation keeps species separate
Difficult to observe in nature
More common in marine species because total geographic isolation is not possible
Sympatric Speciation
Natural selection may favor two equally successful solutions to the same problem
Species stay in one ecosystem even though there is no geographic barrier
Only uses natural selection
Why do we study primates?
We share similarities in behavior and anatomy
They provide models of how adaptation shapes environments that shaped our ancestors
Homology: the existence of shared structure in genes between different species, there is a shared ancestor to create this
Analogy: the existence of similar traits in two different species, but the species are not related, you can understand what selection pressures were present to give rise to the trait
Conversion Evolution
Evolutionary process by which similar traits/adaptations emerge in unrelated species
Happens with analogy
Primates are diverse!
Body size
Social structures
Diet
Nocturnal vs Diurnal
Behaviors
Locomotion
Habitats
What are the characteristics that primates have in common?
Hind-limb dominant locomotion
Nails instead of claws
Grasping hands and feet
Reduced olfaction and enhanced vision
Foward-facing eyes encased in bone
Relatively large brain
Long gestation
Small litters
Long juvenile period
Long lifespan
Increased dependence on learning and behavioral flexibility
Primate Biogeography
Tropical animals
Mostly forest-dwelling, arboreal animals
Modern range
Americas, Africa, Asia
Ancient range
Included North America, Europe
Key Features of Primates
How does the diet of a primate impact its home range?
Availability
Seasonality of food
Some primates are quite territorial
Home ranges do not overlap
Why so territorial?
Lemurs
Gibbons
Access to males and resources
Some primates are not as territorial
Home ranges do overlap
Territorial or not?
Costs/Benefits
Primate Sociality
Why are primates social?
Shared resources
More mates
Impacts hormones
Predator avoidance
Costs
More competition
Disease transmission
Five basic types
Mating Strategies
Monogamy/pair-bonding
One male, one female
Polyandry
One female, multiple males
Polygyny
One male, multiple females
Polygynandry
Multiple males, multiple females
Primate Taxonomy
There are approximately 300 different species of primates in the world
They are not all equally related to one another
Using genetic and morphological data, scientists can split the primate order into two large suborders:
Strepsirrhini (strepsirrhines)
Haplorrhini (haplorrhines)
Strepsirrhines
Tooth comb
Slightly smaller brain
Tapetum (reflective layer in back of the eye)
Divided into to infraorders
Lemuriformes (lemurs)
Lorisformes (lorises and galagos)
Hominoids (apes)
Lesser apes
Orangutans
Great apes
Family Hominiade (great apes)
Orangutans (Pongo)
Gorillas (Gorilla)
Chimpanzees (Pan)
Bonobos (Pan)
Humans (Homo)
Overview
Humans are equally related to chimpanzees and bonobos
Humans shared a common ancestor with chimpanzees and bonobos 5 to 7 million years ago
History of Research: Chimpanzees
1925-1940: studies on captive chimpanzees
The Mentality of Apes
1960s-1970s: studies on wild chimpanzees
Jane Goodall: Gombe Stream National Park
Toshisada Nishida: Mahale Mountains
History of Research: Bonobos
1928: Harold Coolidge and Ernst Schwartz discovered the “pygmy chimpanzee”
Studied in captivity due to the Congo civil war
Current Perspectives
Past research:
Wild chomps vs. captive bonobos
Current:
Larger perspective and test subject size
Physiological Differences
Bonobos: “Pygmy chimp”
Misnomer
Distinct body proportions
Shorter upper limbs
Longer lower limbs
Bonobos: slender build, bright pink lips, black face
Chimpanzees: robust build, face color changes with age, dark lips
Sexual Dimorphism
Inherited sex differences: size, shape, color
Chimpanzee Social Organization
Fission-fusion:
Band together and disperse (size of the group in flux)
Large groups that form smaller parties
Party size depending on resources
Male philopatry
Male dominance and hierarchical
Females disperse in adolescence
9-14 years old
Transition can take 2 years
Female hierarchy in a new group:
Unrelated to females
Age-based
Chimpanzee Parental Care
“Promiscuous” mating patterns
Among other types
Mothers provide majority of care
Infanticide has been observed in:
Gombe, Mahale, and Kibale
Explained by sexual selection
Uncertain paternity
Chimpanzee Mating Patterns
Restricitive: The dominant male restricts access to fertile females
Consortship: adult pair leaves the community
Extra group: females leave
Chimpanzee Warfare
Chimpanzees and Humans:
Only primates to engage in coalitionary warfare
Chimpanzees:
Highly territorial
Kill and eat other primates
More likely to threaten
Killing is the last strategy
Bonobo Social Organization
Fission-fusion
Groups range from 1 to 20 bonobos
Male philopatry, female dispersal
Females live around 7-9 years old
Strong female-female bonds
As group size increases, male-female bonds increase
Males and females interact to
Mate
Kinship ties
Rank acquisitions
Mother-son pairs
Related mixed-sex pairs interact more frequently than unrelated mixed-sex pairs
Strong female bonds keep males away from food
Bonobo Sexual Behaviour
Most defining characteristic of Bonobos
Purpose of sex:
Reproduction
Dominance
Rank
Bonobo Parental Care
“Promiscuous” mating patterns
Paternal uncertainty
Fathers do not invest
Emphasis on maternal care
Infanticide is rare
How do humans compare to chimpanzees and bonobos?
Emotions
Chimpanzees display similar emotions as humans
Nonverbal communication
Kissing, embracing, holding hands, hurling rocks
Intelligence
Sophisticated cooperation
Childhood
Long childhood
Culture!
Culture in Chimpanzees
Chimpanzees tool use
Occupy many different habitats
Observed in more than 25 contexts
Considerable variation in type and purpose
Mainly used to acquire insects
Tool Use in Bonobos
Study conducted in Lomako
Examined cultural patterns found in chimpanzees
14 of 65 traits found in Bonobos
Branch dragging, leaf sponge, branch clasp, branch shake, etc.
Sex Differences
Bonobos
Females are more avid tool users than males
Larger tool range behavior
More tools for play and food acquisition
Chimpanzees
Females are more avid tool users than males
Primate Mating Systems
Mating systems: the way animals find mates and care for their offspring
We are primates.
There is variation in primate mating systems
There are some basic rules in mammals
Life History Theory
Three tradeoffs that all species make:
Reproductive effort
Somatic effort
Growth
Example: Pregnancy
High investment in reproduction
Low investment in growth
Low investment in maintenance
The immune system down-regulates
The immune system sees the fetus as a parasite
Asymmetrical investment in offspring
Males' reproductive success is limited by access to mates
Female reproductive success in limited by access to resources
Males do not invest when…
They can easily use their resources to secure additional mates
When caring for offspring would not increase their offspring’s fitness
Trivers’ Parental Investment Theory
Inter-sexual selection
More investment = more selective
Intra-sexual selection
Less investment = more competitive
Intrasexual Selection
Males compete for territory, control of females, or opportunities to fertilize
Combat is a common form of pre-mating competition
Intersexual Selection
When males cannot monopolize resources, females may be able to “choose” among the males
Females choose males based on tail lengths, which is presumed to indicate the relative fitness of a male
Sex differences
Humans:
Sexual dimorphism
Ornamentation and appearance
Same-sex competition?
Secure mates?
Signal quality?
Signal resources?
Sexual vs Natural Selection
Guppies - sexual selection can favor traits that reduce survival
Natural selection favors traits that make the male blend in
Sexual selection favors traits that make the male stand out
Parent-Offspring Conflict
Trivers (1974)
Conflict over care
Parental care is costly:
Trade-off: current vs future reproduction
Time: Lost mating opportunities
Energy: energy invested in one offspring cannot be placed in another
Conflict over Care…
Parents distribute resources evenly
Parents and children want the same resources
Sibling rivalry
A small age difference between siblings leads to more conflict over resources
Breastfeeding & Weaning
Breastfeeding is costly
Cost increases over time
Results in mother-infant conflict
Increased birth spacing
Neglect
Comparisons with Other Primates
Baboons
Weaning conflict long and intense
Frequent turnover of the Alpha male
Siblings generally share 25% of genes
Gorillas
Less weaning conflict
New alpha male will kill infants
No relation to them
Infanticide
Parental investment is a limited resource
Allocation
The women who sacrifice their offspring tend to be young, poor, unmarried, and socially isolated
The Evolutionary Psychology of Attraction
Common, prevailing view for women’s preferences:
Males who can provide a range of resources for the female
Food
Shelter
Protection from other males
Females should have evolved preferences for males who:
Have good financial prospects
Are older than themselves
Have higher social status
Display hard-working and industrious character
Males are looking for women with a youthful appearance
Beauty:
Unwrinkled skin
Bright eyes
Full red lips
Glossy hair
Lack of facial blemishes and facial hair
Facial symmetry
Body size and shape
Waist-to-Hip ratio
WHR = measurement at smallest point of waist and widest point of hips
Before puberty = no sex differences
After puberty = female fat accumulation around hips
Western averages:
Healthy men = 0.85-0.95
Healthy (premenopausal) women = 0.65 - 0.80
Darwin: there are no universal signs of beauty
1980’s: Evolutionary psychologists
Universal mate preferences
Body fat distribution
Hips and buttocks
Associated with menarche
“Honest Signal” of fertility
WHR of 0.7 is a signal of attractiveness
Low WHR:
Indicates that a woman is not pregnant
There women have higher circulating b-estradiol and progesterone
Might facilitate conception during in-vitro fertilization
Women with a high WHR and low BMI have a harder time becoming pregnant
Men with low testosterone have lower WHR
Hadza of Tanzania
WHR of 0.9 is considered most attractive
However, the profile of women mattered
When viewed from the side, men preferred a WHR of 0.6
Matsigenka of Peru living in the Amazon
WHR of 0.9 is considered most attractive
Problems with WHR Studies
Images are not realistic
What is being measured: BMI or WHR?
Inconsistent manipulators of the study stimuli:
Stimuli is often not culturally or ecologically relevant
Status of participant (Ex. hungry)
Tsimane Study
Tsimane men (N=66)
Controlled for BMI to look at preferences
Polygyny
Why would a woman put up with polygyny?
Resources
Genes
Examples: suppose it costs two units of stuff to produce a viable offspring
Male coercion
Only if men use force and will not lead to higher reproductive success
Polygyny Threshold
Females select males because of resources will lead to higher reproductive success
Dogon of Mali in West Africa (Strassman)
Patrilineal
Arranged marriage
Male dominated
46% have more than one wife
IMR: high
20% of babies die in the first year
46% of children die by age five
Wealthy men:
More wives
Male Coercion Model
Polyandry
Non-classical polyandry
Mostly informal
No co-residence
Partible paternity: 41% of South American tribes studied
Offspring more likely to live to adolescence because the child had more fathers
Sex with secondary father may cease when child is born
Low frequency
Classical
Organized at the state level
Agricultural and Agropastoralism
Cohabitation
9% to 50% of all marriages
Formal (residential) polyandry
Co-residence
Monomarital Principle
Land is scarce
Less land fragmentation
Marriage of brothers allows land to stay in family
Sri Lanka and India
Skewed Sex Ratio
Shortage of women from polygyny
“Junior husband” to have some chance at reproduction
Male Absenteeism
Fear of female abduction
Inuit
High male mortality
Fraternal polyandry to protect wife
Father Effect
Consequences for the survival and well-being of a child
Partible paternity
Leads to informal polyandry
Children with two fathers were more likely to survive to age 15
Evolutionary Biological Theories
Classical: Operational Sex Ratio (OSR)
Male-biased
The rarer sex (females) becomes more picky
Male-Cooperative polyandry
Joint male defense of a territory
When a female’s territory overlaps with territories of other males