Anthropology help wanted
Asahad
11_EvolutionGeneticsVariationRace_UPDATED11.pptxEvolution, Genetics, Human biological variation, & RACE
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This Topic
Why is evolution important?
Understanding our origins
Understanding human variation
Going to begin with a very brief history of evolutionary thought leading to the “modern synthesis”
Then will shift to focusing on what evolutionary theory can tell us about human variation
We can then use our understanding of human biological variation to critically assess the concept of race
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Evolution: A Key Theory in Anthropology
Evolutionary Theory
Evolutionary theory is testable, unified, and fruitful:
Testable means that independent hypotheses support one another
Unified means that it explains a wide array of material evidence
Fruitful means it suggests new possibilities for research
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Evolutionary theory claims the following:
Living species change over time and give rise to new species
All organisms ultimately share a common ancestry
The theory of evolution allows us to explain the patterns of similarity and diversity common to life forms.
Material evidence for evolution relates to change over time and across space.
Geological research uncovered the fossil record, noting differences between living and fossilized organisms, indicating change over time.
Study of patterns of distribution of living organisms points to change across space.
Darwin’s study of finches on the Galapagos Islands found there was both great diversity between finches on the different islands and the mainland, they were also very similar.
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Pre-Darwinian Views: Ordering Nature
See Table 3.1 of text
Plato and Aristotle
Essentialism: living creatures exhibit an unchanging essence or nature
Single, graded continuum of animals and plants going from less perfection (plants) to more perfection (humans)
a.k.a. the Great Chain of Being
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Essentialism
Living creatures exhibit an unchanging nature (essence).
Organisms, such as cows, may vary but share the same essence, that makes it a cow and not a horse.
Organisms that share the same essence are part of the same “natural kind.”
Each natural kind of organism is sharply distinct from all other kinds.
This notion can be traced to the Greek philosopher Plato.
The Great Chain of Being
Living creatures are created by God and overlap with closely related kinds of creatures (continuity).
Creatures are ordered by degree of sacredness in an unbroken chain leading to the divine (unilinear gradation).
The Great Chain encompasses all logically conceivable organisms (plenitude).
It is based on the ideas of Greek philosopher Aristotle.
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Pre-Darwinian Views: Ordering Nature
Carolus Linnaeus (1707 - 1778)
Developed the modern system of taxonomy
Taxonomy = the science of biological classification
Genus (plural = genera)
Binomial nomenclature
e.g., Homo sapiens
Systema Natura (1735)
-Carolus Linnaeus was a Swedish naturalist who is known for his contributions to the system of classification used today by all biological scientists, including physical anthropologists; he is also thought of as one founder of modern ecology
-the science of classification that Linnaeus invented is referred to as taxonomy and any group of organisms assigned to a particular category is referred to as a taxon
-his hierarchical scheme of nomenclature provided unique names for all varieties of plants and animals where each plant and animal was provided with a higher level genus name and a lower level species name; a single genus could include one or more species
-this hierarchical naming system is referred to as binomial nomenclature
-for example, when Linnaeus named human beings Homo sapiens, Homo being the genus, sapiens being the species, he though that there were species and subspecies of living humans. By including humans into this scheme was controversial because it defied contemporary thought that humans, made in God’s image, should be considered unique and separate from the rest of the animal kingdom
- the presence of more than one level in his taxonomy acknowledged different degrees of physical similarity
-Linnaeus presented the first version of his taxonomy in his book Systema Natura in 1735. He went on to classify groups of genera into orders and groups of orders into classes
-Both Ray and Linnaeus were committed to the notion that life-forms were static, fixed at the time of the Creation. In later editions of his Systema Natura, Linnaeus hinted at the possibility that some species may be related to others because of common descent
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Evolving Organisms
Comte de Buffon (1707 – 1778)
Observed plants and animals from many habitats
Noted patterns in variation
Proposed mechanism:
Each region has typical influence
Populations entering a region are changed by its influence
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-those theories can only be used to explain the change that is occurring to landforms
-we must not forget that there is evidence for change in life forms as well
-by the late 1700s, a handful of scientists had begun to argue that contrary to religious doctrine, organisms are not fixed – they change over time, sometimes in dramatic waves
-several researchers began to suggest models to explain the change that researchers had been seeing in lifeforms
-the 4 scientists that we will look at are Compte de Buffon, Jean Baptiste Lamarck, Charles Darwin, and Alfred Wallace
-Georges-Louis Leclerc, Comte de Buffon was a French naturalist, mathematician, and biologist,
-Buffon studied plants and animals and while doing so he noticed patterns in variation between species of plants in different areas
-he had recognized the dynamic relationship between the external environment and living forms
-In his book, Natural History, published in 1749 he stressed the importance of change in the universe and in the changing nature of species
-Buffon believed that when groups of organisms migrated to new areas, they gradually became altered as a result of adapting to a different environment
-Although Buffon rejected the idea that one species could give rise to another, his recognition of the external environment as an agent of change in species was extremely important
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Evolving Organisms
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Jean-Baptiste Lamarck (1744 – 1829)
Inheritance of acquired characteristics (Transformational evolution or Lamarckian evolution)
Each environment has different demands
Animals change over their lifetimes to adapt to these demands
These changes are passed directly to their offspring
Also not a process of selection, but did introduce the idea of adaptation
-French Naturalist Jean-Baptiste de Monet, better known by his title, Chevalier the Lamarck, speculated that plants and animals not only change in form over time but do so for purposed of self-improvement
-Lamarck suggested a dynamic relationship between species and the environment such that if the external environment changed, an animal’s activity patterns would also change to accommodate the new circumstances. This would result in the increased or decreased use of certain body parts; and consequently, those body parts would be modified
-according to Lamarck, these physical changes would occur in response to bodily ‘needs’ so that if a particular body part felt a certain need, ‘fluids and forces’ would be directed to that point and the structure would be modified
-Since the alteration would make the animal better suited to its habitat, the new trait would be passed on to its offspring. This process is called Lamarckian inheritance of acquire characteristics or the use-disuse theory or more simply, Lamarckism .
-We know that Lamarck’s mechanism for evolution was wrong, offspring do not inherit traits acquired by their parents; however, his work was the first major attempt to develop a theory built on the premise that living organism arose form precursor species.
-Lamarck was also convinced that humans evolved from some apelike animal
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-Lamarck’s theory is often described by giving the giraffe as a hypothetical example
-having stripped all the leaves from the lower branches of a tree – the environmental change, the giraffe tries to reach leaves on upper branches. As ‘vital forces’ move to tissues of the neck, it becomes slightly longer, and the giraffe can reach higher; this longer neck is then transmitted to offspring, with the eventual result that all giraffes have longer necks than their predecessors had
-So, according to this theory, a trait acquired by an animal during its lifetime can be passed on to offspring
-Because Lamarck’s explanation of species change isn’t genetically correct, it’s frequently made fun of and dismissed. But, point of fact, Lamarck deserves a lot of credit because he emphasized the importance of interactions between organisms and the external environment in the evolutionary process. Even more so, he was one of the first to acknowledge the need for a distinct branch of science the deals solely with living things, he coined the term biology.
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Evolving Organisms
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The development of the theory of evolution by natural selection was developed independently by two men:
Charles Darwin (1809 – 1882)
Alfred Russel Wallace (1823 – 1913)
Both Darwin & Wallace familiar with:
Debates in geology
Debates in evolution
Theories of Thomas Malthus
Human populations grow constantly
Resources (food, land) are finite and place limits on population growth
Both saw variation in nature through their travel/work
-Now for the big hitters in the discovery of evolution by natural selection: we’re going to talk about two naturalists, that is Charles Darwin and Alfred Russel Wallace
-Independently from Darwin, Wallace had arrive at most of the same conclusions that Darwin had. Both men had been award of their shared interest in the subject, and both men formulated their theories simultaneously. They did have some correspondence, via letter mail. Concerned that Wallace would publish first, Darwin published his results as quickly as possible.
-Who, then, discovered natural selection, the key mechanism that explains evolution? Some would argue that Wallace should be given primary credit for the theory. However, because Wallace had not amassed the extensive body of evidence needed to support the theory, Darwin is generally recognized as the discoverer so, we will cover them both equally, or try to anyway!
-of course both Darwin and Wallace were very familiar with the current debates in the related fields of geology and biology and the current ideas regarding evolution. Particularly influential was the work of Thomas Malthus, a political economist. Malthus book, An Essay on the Principle of Populate, made the case that an abundance of food – enough to feed anyone born – would allow human populations to increase geometrically and indefinitely. Malthus was probably one of the most influentially of all great scientists of the time on the work of Darwin and Wallace; putting it simply, the essay argued that there was simply not enough food for everyone born so populations are limited by food supply
-so, the question is, who survives to a reproductive age? the answer is, those who can successfully compete for food
-applying Malthus’ demographic ideas to human and non-human animals, Darwin concluded that they have some special attribute or attributes; that an individual characteristic could facilitate survival was a revelation! During their voyages to far off places, Darwin on the Galapagos islands off the coast of Ecuador and Wallace in the Amazon and Indonesia and Malayasia, both men saw variation in nature and both men independently sought out to answer the question of why and how.
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Evolving Organisms: Darwin
Charles Darwin (1809 – 1882)
One of six children, wealthy family
Studied Medicine, Theology but interested in the natural sciences
HMS Beagle – Galápagos = Finches
The Origin of Species by Natural Selection (1859)
Change in organisms over time – this change being neither negative or positive
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-So, we’ll discuss Charles Darwin first
-Charles was one of 6 children and grew up in a very wealthy family with influential ties to intellectual circles. He was sent to study medicine, and it was during this time that he learned of Lamarkism. During this time, the 1820s, people came to associated evolution with atheism and politic subversion; people thought that if evolution was accepted, the church would crash, the moral fabric of society would be torn apart, and civilized man would return to savagery. While at university studying medicine, Darwin befriended several professors who were followers of Lamarckism. although indifferent to religion, following his medicine degree he went to study theology. it was during this time that his interest in the natural sciences grew.
Following his graduation in 1831 he was invited to join a scientific expedition that would circle the globe. on December 17, 1831 Darwin set sail aboard the HMS Beagle; this voyage took almost 5 years. When he first boarded the boat, he was a firm believer in the fixity of species, remember, that living organism do not change over time; however, during the voyage he started having doubts. then, there was a stopover in the Galapagos Islands, off the coast of Ecuador. Here Darwin noticed that the vegetation and animals on the islands shared many characteristics with those on the mainland, but they weren’t identical; even more so, Darwin noticed that birds, specifically finches, on one island were somewhat different than the finches on another island
-he had, in reality recognized that the various Galapagos finshes had all descended form a common, mainland ancestor and had been modified over time in response to different island habits and dietary preferences but it wasn’t until her returned home to England that he recognized the significance of this variation
The Descent of Man (1871)
Monkeys, apes, and humans are descended from a common ancestor who lived a long, long time ago
Physical (and genetic) divergence of that common ancestor into monkeys and humans caused by process of natural selection
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Evolving Organisms: Wallace
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Alfred Russel Wallace (1823 – 1913)
Born in a small village in Monmouthshire, Wales as the 8th of 9 children
No formal education
The Mischief – Amazon
“On the Tendency of Varieties to Depart Indefinitely from the Original Type” (1858)
-Unlike Darwin, Alfred Russel Wallace was born into a family of modest means. Wallace was born in the village in Monmouthshire, Wales. He was the eighth of nine children; he went to work at the age of 14 and with little formal education, moved from one job to the next
-he became interested in collecting plants and animals, and in 1848 joined an expedition to the amazon aboard the Mischief . Their intention was to collect insects and other animal specimens in the Amazon Rainforest and sell them to collectors back in England and look for evidence of altering of one species into another
-From 1854 to 1862, Wallace traveled through the Malay Archipelago or East Indies (now Malaysia and Indonesia), to collect specimens for sale and to study nature; it was during these excursions that he made the observations that led him to solve the riddle of how species evolved
-So unlike Darwin, Wallace began his career as a traveling naturalist already believing in the transmutation of species
-in 1858 Wallace published an article suggesting that species were descended from other species and that the appearance of new species was influenced by environmental factors; because of this article, Darwin quickly published his book in 1859 entitled, Origin of Species and the rest is history!
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Lamarckian and Darwinian/Wallacean views of evolution
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Evolution by Natural Selection
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Darwin’s principles of evolution:
1. Producing offspring at a faster rate than food supplies increase
2. Biological variation exists within all species
3. There is competition among individuals
4. Favorable traits lead to fitness
5. Environment matters
6. Traits are inherited, leading to reproductive success
7. Time = more variation different species
8. Geographical isolation new species
-because the story of how Darwin came up with the theory is better known, we will follow that story; however, don’t forget that Wallace came up with the same idea, although he didn’t call the process by the same name as Darwin. Following his return from the Galapagos islands on the HMS Beagle, Darwin returned to England to formulate his idea that we now know as natural selection. natural selection is the differential reproductive success over multiple generations. Darwin had realized that this differential reproductive success was the key to evolution. For Darwin, the explanation of evolution was simple
There are 8 basic principles, as he understood them and they are as follows:
1. all species are capable of producing offspring at a faster rate than food supplies increase. This idea of course was borrowed from Malthus
2. There is biological variation within all species;
3. Because in each generation more offspring are produced than can survive, and owing once again to limited resources, there is competition among individuals. obviously this doesn’t mean that people are running around with guns.
4. individuals who possess favourable variation or traits, for example speed, resistance to disease etc) have an advantage over those who don’t have them. in other words, they have greater fitness because favourable traits increase the likelihood of survival and reproduction. This is where the saying, survival of the fittest came into play
5. the environmental context determines whether or not a trait is beneficial. what is favourable in one setting may be a liability in another. consequently, the traits that become most advantageous are the result of a natural processs
6. traits are inherited and passed on to the next generation. because individuals who possess favourable traits contribute more offspring to the next generation than others do more favourable traits therefore become more common and those traits considered less favourable are as common
those individuals who get to produce more offspring than others are said to have greater reproductive success, or fitness
7. Over long periods of time, successful variations accumulate in a population so that later generations may be distinct from ancestral ones thus, over time, a new species may appear
8. Geographical isolation also contributes to the formation of a new species when a population is geographically isolated from another one, they begin to adapt to their different environments in the end they may become distinct species since favourable traits in each environment will be selected for, and unfavourable traits selected against. This will affect what traits get passed on to offspring in each area
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Heredity: Genetic Revolution
Darwin cont.
Understood then that variations (principle 1) transmitted through heredity (principle 2) and that different variants leave different numbers of offspring (principle 3 or natural selection) but what was the mode of inheritance?
Pangenesis was a theory of heredity favoured by Darwin and others:
Each parent generated multiple particles reflecting his or her unique traits
These particles blended in different ways in each offspring
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OK so from Darwin we have this idea of how change occurs in populations but not the mechanism – genetics allows us to understand and explain heredity.
NOTE: This is NOT a genetics course. As such we will only be discussing from a historical perspective versus going over the finer details of modern genetics. This means while the background provided in your text is useful if you are unfamiliar with the basics of genetics or looking for a review, I will treat it as such. So you are NOT expected to be fully versed in genetics but just have a broad understanding of why genetics is important to understanding human variation – basically that it is the mechanism for the inheritance of traits.
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Genetics
GENETICS = The study of heredity and the variation of inherited characteristics
Mendel’s Experiments
Mendelian inheritance views heredity as based on non-blending, single particle (GENE) inheritance
Based on several experiments where Austrian monk Gregor Mendel (1822–1884) bred pea plants & devised several principles:
Of dominance and recessiveness
Of segregation
Of independent assortment
Showed that traits passed on to a child can be:
Dominant traits—particles expressed in an organism
Recessive traits—particles not expressed in an organism
= Principles of Dominance and Recessiveness
Genes are the biological unit of heredity
Genes are portions of DNA molecules that code for proteins responsible for phenotypic traits
There can be several forms of a given gene, called alleles
Chromosomes are sets of paired bodies in the nucleus of cells that contain the DNA and genes
We can look at variation then in:
Genotype
Phenotype
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Evolutionary Theory Revisited
Microevolution
concerned with short-term evolutionary changes that occur within a species over a few generations of ecological time (time involved in adapting to ecological settings)
Macroevolution
concerned with long-term evolutionary changes, including the origin of new species and diversification over space and millions of years of geological time.
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What Is Microevolution?
The Modern Evolutionary Synthesis and Its Legacy
Also known as neo-Darwinism
Developed in the 1930s and 1940s to combine Darwin’s concept of natural selection and Mendel’s ideas about heredity
Helped undermine the 19th century concept of biological race
Recognizes that all human beings are part of a single species
Examines human biological variation from a population perspective
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What Is Microevolution? cont’d
Population genetics involves the statistical analysis of short-term evolutionary change in large populations
Genes are polymorphous, meaning that alleles can have a range of different forms
Gene frequency is measured by calculating the occurrence of particular alleles in a population’s gene pool, the totality of the genes of a given population or species
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What Is Microevolution? cont’d
Most variation in traits is clinal
Cline: gradual shift in distribution of phenotypes between populations over space, as alleles increase or decrease in frequency
Few sharp boarders in traits between human populations
Most groups are similar to nearby groups
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Microevolution: Human Variation & the Four Evolutionary Processes
Shifts in gene frequency in a population are due to four processes:
Natural selection
Mutation
Gene flow
Genetic drift
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Table 7.2
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An Example (see CH 7)
Sickle-cell anaemia
Relatively common in populations in malarial regions
Result of selective pressure of malaria
Single copy of the allele helps to protect against malaria, thus individual is more likely to survive and reproduce
Balancing selection
Researchers have studied the gene sequence associated with this trait to understand its origin and spread through populations
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Hemoglobin S gene: inheritance from one parent and not the other (heterozygous) = just have sickle cell trait = resistance to malaria
Inheritance from both parents (homozygous) = sickle cell disease (still have resistance to malaria but with negative side effects of disease itself including organ damage from lack of appropriate oxygen, jaundice, acute chest crisis (fever, chest pain, hard breathing), bone damage (including bacterial infection), stroke
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https://www.youtube.com/watch?v=5NdMnlt2keE
Review: The Five Fingers of Evolution
From Understanding Variation via Evolution to Race
From Evolution & Genetics to Racial Classification
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Historical Views on Human Variation
Recall early focus on understanding variation in organisms; same ideas applied to humans
Skin colour is the most noticeable way humans vary so most systems were based on it
~1350 BCE Egyptians were classifying people based on skin colour
16th century sees exploration of New World
Increased awareness of human diversity
-the first step toward understanding diversity in nature is to organize it into categories that can then be named, discussed, and perhaps studied
-historically, when different groups of people came into contact with one another, they tried to account for the physical differences they saw
-because skin color was so noticeable, it was one of the more frequently explained traits, and most systems of racial classification were based on it
-as early as 1350 BC, the ancient Egyptians had classified humans based on their skin color: red for Egyptians, yellow for people to the East, white for those to the north, and black for sub-Saharan Africans
-in the 16th century, after the discovery of the New World, several European countries embarked on a period of intense exploration and colonization in both the New and old Worlds
-One result of this contact was an increased awareness of human diversity
-throughout the 18th and 19th centuries, European and American scientists concentrated primarily on describing and classifying the biological variation in human as well as in non human primates
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Early Racial Classification Schemes
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Carl Linnaeus:
Systema Naturae (1758)
Four racial categories
Homo sapiens afer (Africans)
Homo sapiens americanus (American Indians)
Homo sapiens asiaticus (Asians)
Homo sapiens europaeus (Europeans)
Homo sapiens ferus (Wild men)??
-the first scientific attempt to describe the newly discovered variation between human populations was Linnaeus’ taxonomic classification which placed human into four separate categories
-Linnaeus assigned behavioural and intellectual qualities to each group, with the least complimentary description going to sub-Saharan, dark-skinned Africans
-this ranking was typical of the period and reflected the almost universal European ethnocentric view that Europeans were superior to everyone else
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Early Racial Classification Schemes
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Johann Friedrich Blumenbach:
1752 – 1840
Five racial categories
Ethiopian
American
Asian
Caucasian
Malayan
-Johann Frierich Blumenbach (1752-1840), a german anatomist, classified humans into five races
-this guy is considered to be the father of biological anthropology
-after studying several hundred skulls he had collected from around the world, he concluded that there were five races of people, Mongoloids, Malays, Ethiopians (Africans), American Indians, and Caucasoids
-these types were static, that is, they did not change over time
-although his categories came to be described as white, yellow, red, black, and brown, he also used other criteria – not just skin color
-he emphasized that racial categories based on skin color were arbitrary and that many traits, including skin color, showed overlapping expression between groups
-his study set the tone for the popular perception of human variation : that human beings come in categorical types called races
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Changing/Challenging Ideas of Race
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Ashley Montagu (1905 – 1999)
Opposed the term “race”
Argued the term has no scientific validity
Advocated the use of the term “ethnic group”
A group defined in terms of sociological, cultural, and linguistic traits rather than perceived biological variation
-Ashley Montague was an anthropologist on a mission
-he was directly opposed to the term race
-he advocated the use of the term ethnic group
-he didn’t create the term, but was in favour of its use over the term race
-he liked the term because it didn’t just include biology, but focused on sociology, culture, and linguistics – all things that he thought were important in the classification of people
-his work has had a large impact on how we view the ideas of race today
-he had a hand in coming up with the United Nations Statement on Race in 1950
-even today, he inspired the AAA statement on race
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The Race Concept
Race as everyday “fact” of life
What race are you?
System of folk heredity (Marks 1994)
System of race identification generally accepted in a society
Informally learned from childhood
Does not always work
“mixed” races
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However…
While race is seen as biological, recall that human variation is clinal
There are no “natural” boundaries
Arbitrary divisions and definitions are still necessary
When does “white” begin and end?
Which parent defines “race”?
When do you stop? How many races are there?
Plus human populations interbreed
Biological race is not “real”
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Clinal = continuum, graduate differences across an area (e.g., height – where do you draw the line at short, medium, tall)
Therefore biological race is NOT objective but rather just as subjective as system of folk heredity or social race.
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Race & Biology
Concept of “race” is biologically meaningless because:
More genetic variation found within so-called races than between them
Distribution of some traits does not match the distribution of others (e.g. skin colour and hair type)
Most genetic variation is seen within racial groups
Variation between racial groups accounts for relatively small % of total human variation
Reflects broad nature of classic racial groups
Reflects fact that racial groups are defined using few selected traits
mtDNA and Y DNA variation can be used to trace group relationships
All human groups appear to share a relatively recent common ancestor
Smaller and more closed related groups may share some typical traits
Reflects recent common ancestry
They still show much more internal variation
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Deconstructing Racial Features: Skin Color
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Most important factor in racial classification a.k.a. folk taxonomies
Skin colour is an adaptive response shaped by natural selection
Three influences on skin color
Hemoglobin
Carotene
Melanin
A brown pigment that determines the darkness of the skin – secreted by melanocytes
-now we’re going to focus on some of the key traits that scientists and everyday people have been using to make up racial groups
-I would have to say that skin colour has been the trait that is used the most to place someone in a racial category
-three substances influence skin color: haemoglobin, the protein carotene, and most important, the pigment melanin
LET US LOOK AT MELANIN IN PARTICULAR -one of the most profound environmental factors that humans deal with daily is solar radiation, or the sun’s energy output, this output plays a central role in the evolution and development of skin color
-in daylight, skin – the largest organ that accounts for 15% of our total body weight – is exposed to ultraviolet radiation, a component of solar radiation
-when first exposed to UV radiation, light skin reddens – the process commonly called sunburn
-with ongoing exposure, pigment cells, the melanocytes increase the number and size of melanin granules (melanocytes are the melanin-producing cells located in the skin)
-melanin is the brown pigment that determines the darkness or lightness of a human’s skin color due to its concentration on the skin
-at the same time, the outer layer of the skin thickens
- this darkening, also known as tanning, and the thickening, servers to retard penetration of the skin by radiation thus protecting the individual from sunburn and possibly from cancer
-because melanin is a natural sunscreen, individuals with the most melanin receive the most protection; thus, people with dark skin, such as in equatorial Africa, are able to tolerate more exposure to sun than are those with light skin
-dark skinned people have a sun protection factor of 10 to 15
-light skinned people have an SPF of between 2 and 3
-around the world, populations with the most melanin have the fewest skin cancers
-skin color is commonly cited as an example of adaptation through natural selection in humans
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Skin colour variation reflects two opposing clines of skin pigmentation: - Dark to light as one moves away from the equator - Light to dark as one moves away from the poles toward the equator
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Map 7.1
-this figure shows that populations with the most pigmentation are found in the tropics, while lighter skin color is associated with more northern latitudes
Advantage of darker skin:
Prevents sun burn
Prevents destruction of folic acid, important in cell division.
Advantage of lighter skin:
Allows synthesis of more vitamin D on the skin, crucial for healthy development of bones.
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Variation, Environment, & Body Build
Bergmann’s Rule:
General relationship between body size and temperature
Warmer = slender
Colder = robust
Allen’s Rule:
General relationship between limb proportions and temperature
Warmer = longer limbs
Colder = shorter limbs
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Variation & Environmental Stress
Much environmental stress is dealt with through cultural adaptation
Examples?
Cultural adaptation removes much selective pressure on human populations
If culture does not remove the stress it may have a selective effect
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Example: Inuit
Face extreme cold
Cultural adaptations: clothing, dwelling structures, hunting techniques
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Variation & Environmental Stress
The body also deals with stresses through acclimatization
This is a response on the individual level, often reversible
E.g., tanning, increase in red blood cell count at high altitude
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Race & Ancestry
Focuses on genetic relationships
Focuses on geographic origin
Ancestral relationships are traceable
Mitochondrial DNA
Nuclear DNA
Relationships are real, which is why race is frequently used as a “category of convenience” to “capture” ancestry
Medical and forensic applications
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Re-establishing Race in Anthropological Discourse – American Anthropologist 99(3): 517-533
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Race, Ancestry, & Populations
Humans are divided into breeding populations by factors such as:
Geographical barriers (examples?)
Customs and attitudes (examples?)
This can lead to the perception of human populations as discrete “races”
However gene flow is an important factor:
See exchange of mates with other breeding populations
Maintains genetic unity of our species
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Social Race
Race as a social construction
Is very important in many cultures
Social race classifications
Reflect cultures’ choice of important defining characteristics
May include factors such as faith
Deal poorly with boundary crossing
May allow self-definition of race
Involves the racialization of groups
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Social race classification systems have the following signatures.
Racialization – impose a racial character or context on a group/groups. Eg. Jewish people in Nazi germany, “negros” in the US at the time of slavery (people from various parts of Africa, mixing of numerous tribes often with different languages, beliefs, cultures etc.)
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Social Race vs. Ethnicity
Ethnicity
A category primarily based on language, culture, or faith
Need not include shared ancestry
e.g. Jewish, Hispanic
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Social race vs. Ethnicity
Sometimes used interchangeably
Separate definitions can be useful
Definition may differ based on perspective
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Race & Racism
Race as a social divider
Influences perception by others
Racial stereotypes influence responses of others
Defines or limits opportunities
May follow lines of social class
Racism may rest on claimed biological differences
This is why it is important to critically analyze the biological traits used in defining race
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Racism is based on the false belief that along with our physical characteristics, humans inherit such factors as intellect and various cultural attributes
-such beliefs also commonly rest on the assumption that one’s own group is superior to other groups
-already in this course we’ve alluded to certain aspects of racism, in our discussion of the eugenics movement and the persecution of people based on racial or ethnic misconceptions
-what we need to remember is that race is a product of the past
-the concept of race is a relic of the times and conditions which have long ceased to exist
-racism itself is equally a relic supported by no phase of modern science
-it’s important to point out that racism is hardly a thing of the past, and it’s not restricted to Europeans and Americans of European descent.
-and, not surprisingly, racism is a cultural phenomenon, and it continues to be found worldwide today
Often issues of social inequality and social differentiation are directly tied to issues of ethnicity and racism
Often social race categories are entirely based on stereotypes
Stratification – think about dif in race or ethnicity as usually associated with inequalities in wealth, power, prestige, and opportunity
Scientific racism – Henry Harpending (amazing geneticist who promotes positions no longer seen as valid – eg. All African Americans are inherently better at sports).
Other classic examples of scientific racism = The Bell Curve and IQ tests
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Race & Scientific Racism
IQ tests were developed on the assumption that they could provide an reliable measure of intelligence (see CH 7)
There is no single way to define or measure human intelligence
Variations in IQ scores reflect differences in social class, culture, and education:
Students of different “racial” backgrounds but similar social and educational status have similar scores
Score variations are based on individual traits affected by environmental factors
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Race in Japan
Japanese that share the same “blood” are valued = “pure”
Japan sees itself as being homogeneous in “race”, ethnicity, language, & culture
Minorities do exist
Perceived “racial” difference is enough to value one person (or group) over another
Japanese identity and the Burakumin
See In Their Own Words “Burakumin: Overcoming Hidden Discrimination in Japan” p.400
Japanese ethnicity, identity, migrants, & Nikkei http://japanfocus.org/-nobuko-adachi/3410/article.html
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The pure majority define themselves in opposition to others – basically anyone who is not “us”
Japanese see themselves as harmonious, hard-working, and middle class
Residential segregation and taboos on interracial marriage aid in this
Japanese culture is definitely not homogeneous: revealed in mutually unintelligible dialects
10% of Japanese population is a minority of some type ( e.g., Ainu, Okinawans, Burakumin, and immigrant)
Burakumin are a good example of how biology is used to separate ethnic groups i.e., is a biological race concept
- Residentially separated into Buraku neighbourhoods
Stigmatized group of about 4 million
Compared to untouchable caste in India
Are physically and genetically indistinguishable from other Japanese – are separated by lineage and thus “blood”
Buraku address implies membership & is used by companies & schools to discriminate
Have poor housing & sanitation
Less likely to attend high school & university
Limited access to jobs & health care
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Race in the United States
A person acquires their racial identity at birth
Hypodescent
This automatically places the product of a mixed union in the minority (see inferior) group
A child born to a “White” and “African American” couple will be designated “black”
Designations usually stay with a person their whole life
Divides American society into groups that are unequal in their access to wealth, power, and prestige
So race has REAL effects on society
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Race in Brazil
Has fewer exclusionary categories than the U.S. or Japan
Brazilian description of human diversity is more detailed, fluid, & flexible than most other cultures
Are at least 136 terms used for race
Bases categorization on phenotype (thousands of detectable physical differences including skin, hair ,& eye colour; hair shape etc.)
Poverty & skin colour correlated = class status affects racial status
Someone who is poor & light skinned is seen as having darker skin (“money whitens”) BUT also affected by gender and by education
Permits individuals to change their “race” classification
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Role of History
Difference in treatment of “mixed” populations in U.S. & Brazil is historically based
English men, women & families were preponderance of colonizers in U.S.
Portuguese settlers of Brazil were mainly men; many married women of indigenous population & recognized offspring as heirs
Both groups had sex with their slave populations, but Brazilians often freed their progeny
No hypodescent rule developed in Brazil
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Next Topic
The Living Primates
Readings:
Chapter 4
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