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COLORADO / Evolutionary Anthropology / ANT 2020 / How was the first hypothesis tested?

How was the first hypothesis tested?

How was the first hypothesis tested?

Description

School: University of Colorado at Boulder
Department: Evolutionary Anthropology
Course: Introduction to Physical Anthropology 2
Professor: Richard bender
Term: Winter 2016
Tags: #PhysicalAnthropology and #midterm
Cost: 50
Name: ANTH 2020 Midterm Study Guide
Description: Everything that was said to be focused on is in black or bold and black. Side notes and contextualization is in a darker grey. Good luck!
Uploaded: 03/07/2017
18 Pages 23 Views 6 Unlocks
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ANTH 2020 Midterm Review


How was the first hypothesis tested?



March 6, 2017

Mixed format:

- 25 multiple choice

- 15 matching

- 10 True/False

- 50 Questions Total

Covers:

- Lecture  

- Readings on D2l

- All videos in and out of class

Studying Guide:

- Understand large concepts before the small ones  understand broad topics  and organize according to those topics

- Minute details are NOT THAT IMPORTANT

- There will be a question on the exam that will require you to use a  Punnett square

Bolded or black = from professors review slides  

Faded/grey = added notes for further context of material

Science is:


Should the first hypothesis be supported or rejected?



- A process of trying to understand the world by making models, or THEORIES,  which have predictive power.

o Involves observation, hypothesis construction, data collection,  hypothesis testing, communication of results

- Empirical (based on knowledge gained through observation) - A self-correcting process: falsifiability is a key defining trait of the scientific  process

o If you cannot test a hypothesis, it is NOT falsifiable 

The case of Beriberi in the Dutch East Indies (late 19th c.):

- Example of formulating, testing hypotheses

o The Case of beriberi (Dutch East Indies, 1887)


How would you test the second hypothesis?



o Strange nerve disease

o Weakness, loss of appetite, heart failure If you want to learn more check out How do geologists classify metamorphic rocks?

o Bacterial?

o Hypothesis and Testing: Chickens exposed to sick patients’ blood  get sick…but so do some who were not exposed

o Observation: Chicken Diet had changed; polished rice lacks B1  (thiamine)

 What was the original observation? People were getting sick (all  symptoms and deaths)

 What was the first hypothesis? Bacterial issue

 How was the first hypothesis tested? Transfer of blood from sick  patients to chickens

 Should the first hypothesis be supported or rejected? Chickens  were still getting sick

 What would you propose for a second hypothesis? It’s not  

bacterial, but vitamin deficiency Don't forget about the age old question of What are some examples of proven resources?

 How would you test the second hypothesis? Have a control  

group of chickens who are kept on the white rice diet and  

change a separate group of chickens to a different grain with the missing vitamins (thiamine)

Kaneheiro Takaki, Christiaan Eijkman investigated the role of diet bacteria

 ∙     Kanehiro Takaki 

∙    Japanese Imperial Navy: 1/3 enlisted men were ill with berberi o Believed it was Bacterial

∙    English Navy were free from beriberi

∙    Sent Kanehiro Takaki to study in England to better understand beriberi ∙ Change diet  greatly improved

o Changed diet on one ship (to begin with) on a 2 year voyage o Convinced crew to supplement their rice diet with greater protein o Entire Japanese Navy eventually made this change and was greatly  improved Don't forget about the age old question of How an enzyme speeds up the reaction?
If you want to learn more check out Why is economic growth considered relevant?

∙ This study was not widely shared or effective on others (such as physicians in the Japanese military corps) because they received different knowledge  from different avenues

o Japanese physicians, trained by German physicians, did not recognize  Takaki’s findings  

The person credited with finding Beriberi If you want to learn more check out What are the different types of methods?

∙ Christiaan Eijkman

∙ Sent to Indonesia by Dutch authorities (because of massive loss of life) ∙ Observations & experiments with chickens

o Started out with rabbits but saw chickens in his lab were showing  similar symptoms to humans, so he started observing chickens

o VERY LUCKY: Beriberi, it was later discovered, only occurs in humans,  chickens, and pigeons…(any other experiments on other animals would have hit a wall)

o Observed something happening to their nerves, continued injections  (based on bacterial hypothesis)

o Injected chickens were getting sick, then those not injected…then all  chickens were fine! If you want to learn more check out How doe messages flow between cells?

 Eijkman found a new chef started feeding chickens a different  type of rice!

∙ Polished vs. Unpolished rice  BUT wrong conclusion 

o He dismissed vitamin deficiency (which is the correct answer) and  thought the unpolished rice contained an antidote to poisonous  contents in food

∙ Returned home and could NOT repeat this experiment on Dutch Chickens o Chickens, when given a choice, never chose white rice – so he force fed the white rice to the chickens and they DID RECEIVE Beriberi 

o Tired of be scrutinized and attacked by colleagues (and having spent  years on this hypothesis, Eijkman gave in on his theory on Beriberi

The process of science is not easy, and can take a long time. 

Theory: hypothesis that has held up to repeated rounds of testing, does NOT mean  uncertain

Model: accounts for all existing results, generates testable predictions

Belief: theories/models do not require belief; scientists should say “evidence tells  us,” instead of “we believe”

Pseudoscience: it is based on post-diction, not pre-diction

- It explains things people care about that may not have other explanations - Uses scientific-sounding language and jargon

- Does NOT use the scientific method of clearly stating the hypothesis and then making a test

- Usually has an explanation even when idea fails

- Rarely discusses what we don’t know

Science: should be logical – based on facts and data, not opinions

- Clear references are given so that you can do your own fact-checking - Information has been published in peer reviewed journals/other formats - Contrary information is given when it exists, not only the supporting  information

- What is not known is identified

Experiences that influenced Darwin’s thinking: 

1. Observation of diversity of flora and fauna on his voyage aboard the HMS  Beagle  

This voyage made him question the fixity of species…

During Darwin’s time, it was understood that things were just the way they  were and had always been. After his voyage, Darwin wasn’t so sure 2. Experience of an earthquake while in Chile

Began to believe that, not only were species not fixed, but perhaps the Earth  was not fixed and was changing

3. In Argentina, Darwin collected fossil bones of extinct animal forms

Found species that were NOTHING like anything he had seen, yet held  similarities to other species now alive  why did some species persist while  others didn’t?

4. Observation of diversity in ground finches across the Galapagos Island Chain He spent 5 weeks island hopping noticing differences in plants and animals as associated with things like climate  environment factors?

Most popular observation: Ground Finches (closely related animals based on  similarities/only slight differences)

Shared research with other researchers who concluded these finches  could actually be different species 

5. His reading of Thomas Malthus’ An Essay on the Principle of Population (1798) Human populations have the ability to reproduce exponentially, at a faster  rate than food production

However, populations around the world tend to be stable. How?

There is a “struggle for existence”

6. Observation of the power of artificial selection by plant and animal breeders Ex. – Pidgeon’s (selective breeding of pigeons show affectively the large  diversities that could be controlled)

Darwin realized  

1836 – Darwin returns from the voyage of the HMS Beagle 1844 – Darwin prepares his first lengthy “sketch” on his theory of  evolution by means of natural selection

1858 – Darwin receives a manuscript, in which Alfred Russell Wallace had independently conceived of evolution by means of natural  selection

1858 – Darwin and Wallace present their ideas to the Linnean  Society in London, detailing their proposed mechanism for  evolutionary change

On the Origin of species by means of natural selection (1859) Main themes:

- Biological evolution is fact  

- All life descended from a single common ancestor (common descent with  modification)

- Gradualism: differences between organisms evolve by innumerable small  steps over time

- Natural selection is the mechanism of evolution

Darwin concluded that individuals of a species with particularly advantageous  characteristics would be more likely to survive in limiting conditions, and would this  reproduce more successfully than individuals with less advantageous attributes

Natural Selection: How it works 

1. Species produce more offspring than can be supported by available food  resources

2. Limited resources leads to competition between individuals of a species

3. There is biological variation among individuals of a species

4. The characteristics of some individuals are more favorably adapted to their  environments than those of other, leading to:

a. Differential survival

b. Differential reproduction

c. Both lead to greater “fitness” (this is how well we reproduce, NOT how  skinny or fat we are)

5. “Favorable” traits are inherited by offspring

6. Geographical isolation may be a force in the origin of species

Review on Mendelian Inheritance (Assignment 1 slides)

Blending Inheritance: parental contribution is averaged out, or blended, in offspring

Gregor Mendel (1822 – 1884): undertook a systematic investigation of inheritance  using very large numbers of pea plants; demonstrated particulate inheritance

Mendel’s Conclusions:  

(1) PARTICULATE INHERITANCE

- Each hereditary trait is controlled by particulate unit factors, which exist in pairs in  individual organisms; one factor is inherited from each parent

- These factors remain discrete, i.e., unchanged, regardless of external appearance (2) DOMINANCE

- When 2 different unit factors relate to a trait, only one is expressed (dominant)  while the other is not (recessive).

- There must be two copies of the recessive factor present for a recessive form to be expressed.

PHENOTYPE: The observable or detectable expression (e.g. appearance) of a trait.

GENOTYPE: The full set of genetic factors that interact in determining the  phenotype.

HOMOZYGOUS: When two copies of the same genetic factor controlling a trait are  present in an individual (=TRUE BREEDING LINES).

HETEROZYGOUS: When two different genetic factors for a trait are present in an  individual (=HYBRID).

(3) LAW OF SEGREGATION

- During formation of the sex cells (= gametes), the paired unit factors separate, or  segregate, randomly, such that each sperm or egg receives one or the other factor  with equal likelihood.

Population: a group of organisms potentially capable of successful reproduction

- Individuals of a population tend to choose mates from within the group - The largest reproductive population is species

Gene Pool: no changes in allele frequencies, i.e. no equilibrium is occurring in the  population

Evolution: a change in allele frequencies from one generation to the next

- Genetic Equilibrium – no changes in allele frequencies, i.e. no evolutions  occurring in the population

Earwax example  given dominant allele E for sticky earwax and recessive allele e  for dry earwax…

What are the phenotypes if receiving the genotypes Ee from both parents? EE – homozygous dominant

Ee – heterozygous (dominant will show)

Ee – homozygous recessive

Evolution occurs with allele frequencies changing over time (40% sticky  earwax  500 years later  50% sticky earwax)

- Hardy-Weinberg equilibrium – mathematical model of genetic equilibrium,  used to test whether evolution has occurred

 

 

Forces of Evolution

1. Mutation: alteration in genetic material; rare, gives rise to new alleles and  adds variation to the gene pool. Only transmitted to the next generation if  occurs during meiosis. Most are neutral.

2. Natural Selection: alleles that confer an increased likelihood of survival to  reproduction will be passed on to the next generation with greater frequency. [directional selection: finch beak size; stabilizing selection: birth weight]

 3. Genetic Drift: change in gene frequency caused entirely by random factors.  Including sampling error effects [allele frequency more likely to change in  small population] Population bottlenecks, founder effect

Population Bottleneck (type of Genetic Drift)

Happens when a population has been decreased to a very  

small size (in one breeding generation), whether by natural  

disaster or something else

Severely reduces population size and genetic diversity; when  

the population rises again, it can only adapt from that  

low genetic diversity from then on

This is evolution and chance working together

Founder Effect

When one group is cut-off from the rest of their population/  

migrating populations create their own gene pool

Over time they could become different enough that they could  

be seen as different species 

An example of this is the idea that human populations (slowly  

but surely) began leaving Africa and varying from each other

Certain diseases crop-up do to small gene pools

 4. Gene Flow: movement of individuals and their genes between population;  makes populations more similar to one another

 5. Nonrandom mating: inbreeding and assortative (positive and negative)  mating

Inbreeding: within family mating; raises frequency of homozygous genotypes  to all loci

Assortative Mating (AM): negative AM = increases frequency of heterozygous  genotypes for particular loci (red-heads tend not to mate with other red heads because of phenotypic similarities); positive AM = increases frequency  of homozygous genotypes for particular loci (husbands and wives tend to be  the same height and/or IQ)

*Hardy Weinberg Equilibrium assumes that these forces are not operating

Definition of Species

∙ Microevolution: small changes occurring within a species, such as changes in  allele frequencies

o Mostly what we’ve been talking about; many of these can turn into  macroevolution

∙ Macroevolution: large changes produced after many generations, such as the  appearance of new species

Biological Species Concept: group of inter-breeding natural populations, which are  reproductively isolated from other such groups

- Reproductive isolation

o Physical barriers (mountains, rivers, etc.)

o Intrinsic barriers (exists within animals themselves; with their  physiology or behavior)

Recognition Species Concept: Emphasizes unique traits or behaviors that allow  individual members of the same species to recognizes each other for the purposes  of mating

Ecological Species Concept: a group of organisms exploiting a single ecological  adaptation

- Example: Medium ground finches do mate with large ground finches if living  on the same island (but only 10% of the time)

- These offspring do not constitute a new species though because there are  adaptive peaks, and hybrids are below these peaks (so natural selection  would weed them out)

Process of Speciation

Allopatric Speciation: speciation occurring via complete geographic isolation Parapatric Speciation: Speciation involving only partial geographic isolation Sympatric Speciation: speciation occurring in the absence of geographic isolation

- Anaogenesis: one species gradually evolves into a new species over time  (species one no longer becomes recognized in fossil records; but when do you stop calling the new species the old species)

- Claytogenesis: species one an split off into two different species (one turning  into a new species altogether while the other can continue the gene path of  the first species)

Gene: genetic material that encode for the expression of a particular trait

Locus: location of a gene on a chromosome

Allele: alternative versions of a gene (one = gene, but two or more = alleles)

Human Karyotype: 46 chromosomes (23 pairs)

- Autosomes: pairs 1-22

- Sex chromosomes: Pair 23 (X and Y)

o Females = XX

o Males = XY

Two types of cells

Somatic cells:  

- components of body tissues

- 23 chromosome pairs (= 46 chromosomes) in humans (diploid) Sex Cells: (gametes)

- Ova, egg cells produced in female ovaries

- Sperm, sex cells produced in male testes

- 23 chromosomes in humans (i.e., only one member of each pair; haploid) Zygote: union between a sperm and an ovum

Mitosis: 

- Cell division in somatic cells

- Occurs during growth and repair/replacement of tissues

- The result of mitosis is two identical daughter cells, which are genetically  identical to the original cell ( 2 diploid cells)

Meiosis: 

- Production of gametes (sex cells)

- Characterized by two rounds of division that result in four daughter cells,  each of which contains 23 chromosomes ( 4 haploid cells) in humans - Fertilization restores the full complement of chromosomes (diploid number of  46) to the zygote

- Increases genetic variation through crossing over and genetic recombination

DNA (deoxyribonucleic acid)

- Located in the nucleus of the cell

- Comprised of Nucleotides:

o Phosphate

o Sugar (deoxyribose)

o Nitrogenous base

- Complementary Base Pairing:

o Adenine = Thymine (or A = T)

o Cytosine = Guanine (or C = G)

DNA Replication: 

- Occurs during CELL DIVISION

- Original polynucleotide strands separate, leaving their bases exposed.  Original strands serve as TEMPLATES for two new COMPLEMENTARY strands

- Results in two identical copies of the DNA molecule

The Genetic Code: information to make proteins is encoded in the nucleotide base  sequence

 - Codon: a sequence of 3 nucleotide bases, which code for 1 amino acid

 - Gene: sequence of DNA bases that carries information from synthesizing a  particular protein, and occupies a specific chromosomal locus

RNA vs. DNA

RNA:

- Single stranded

- Ribose sugar

 - Uracil base (replaces T in mRNA)

DNA:

- Double stranded

- Deoxyribose

- Thymine base 

Protein Synthesis (PART I): Transcription

- Happens inside the nucleus

- DNA splits in region of gene, and attracts complementary ribonucleotides - Complementary messenger RNA OR mRNA strand is synthesized. This  mRNA will leave the nucleus and travel to the ribosome for protein synthesis

Protein Synthesis (PART II): Translation

- Happens outside the nucleus, at the ribosome

- Transfer RNA (tRNA) molecules bind to the complementary mRNA strand  at the ribosome, bringing with them amino acids specified by the mRNA  codon

- As amino acids are brought to the ribosome, they bind together to form an  amino acid chain

Mendelian Inheritance: 

- Single gene, autosomal dominant-recessive model

- Useful for examining traits with qualitative variation (discrete categories) Codominance: 

- Both alleles in the heterozygous condition are fully expressed, with neither  being dominant over the other

- ABO blood system (type O blood is recessive to BOTH A and B blood types) Sex Linkage (X-linked traits):

- Controlled by genes on the X chromosome, more commonly expressed in  males

- As males (XY) have only one X chromosome, any allele will be expressed,  whether dominant or recessive

o Examples of recessive X-linked traits: Hemophilia, red-green color  blindness

Genetics Beyond Mendel: Non-Mendelian Patterns of Inheritance Polygenic traits: 

- Traits with quantitative (continuous) variation, influenced by two or more genes

o Stature, skin color, eye color

Pleiotropy: 

- A single gene influenced the expression of multiple traits simultaneously o Pigmentation and deafness

Environmental Effects: 

- Many aspects of the phenotype are influenced by the interaction of genes  and the environment

o Genotype sets limits and potential for developmental processes

Around the time of Darwin (19th c.) …

Monogenism: all humans derive from a single, biblical, origin  

Polygenism: human races are different species, descended from different original  pairs

Carolus Linnaeus (1758): Systemae Naturae (10th ed.) = 4 sub-categories of Homo  sapiens

o Swedish botanist/taxonomist

o Formalized distinction among human populations

o Helped characterize the concept of race

 Homo – apes that are more human like

 Homo nocturnes “night dwelling man” OR Homo troglodytes  “cave-dwelling man” (less human-like)

 Homo diurnus “daylight man”

∙ Homo Sapiens (humans proper)

∙ Homo monstrous “anamolies”

∙ Homo ferus (“feral man”/ separated from human contact  

@ a young age and raised feral)

Samuel Morton (1820s, 1830s): collected and measured hundreds of human skulls  to confirm there were differences in brain size across the ‘races

∙ Collected and measured hundreds of human skulls to confirm there were  differences in brain size across the ‘races’ 

o Proponent of polygenism

o English supposedly had the largest brain, then Chinese, southeast  Asia/Polynesian, American Indians, and Africans/Australian aborigines  last

‘Race and science’ exhibitions

Exhibits in which people were arranged in the evolutionary hierarchy – darkest to  lightest skin color (etc.)

∙ London 1851: site of first international fair

o Included ‘anthropological study’ sections

o Introduced colonialized people as a backward spectacle

o Millie and Christine McCoy (conjoined twins born into slavery)  Sold, bought, and stolen to be shown as spectacles

o Ota Benga (pigmie)

 After exhibits were over, Ota Benga was sent to the Bronx Zoo  (he was believed to be no more than another animal)

 African American legal retaliation allowed him to leave his  

monkey cage during the day in a white suite  

o Saartjie Baartman (hot taught Venus/anus?)

 Took up domestic service in Africa (family and lover dead)

 Had a large butt caused by an actual medical condition

 Died at age 26; her body was dissected by French scientists, a  cast of her body and genitals were displayed in a museum

This is Pre-Darwin thought and rational.

Charles Darwin (1871): The Descent of Man

- Monogenist  all humans were the same species, any distinction between  groups, such as race = arbitrary

Physical anthropology and the race concept: Changes over time: 

Franz Boas (1858-1942) 

- Rejected biological determinism

- Emphasized importance of variation, environment

- Head shape in US immigrants experiment (1908-1910)

Ales Hrdlicka (1869-1943): 

- Views on race mixed; founded AJPA and AAPA

Earnest Hooton (1887-1954): 

- Joined Harvard in 1913 – supervised over 20 PhDs (very influential) - Record of views on race conflicting and complicated

- Biological determinist, eugenicist

Carleton Coon (1904-1981): 

- The Origin of Races (1962): each of five human ‘races’ had become human at different times

- Close contact with Carleton Putnam during Putnam’s writing of Race and  Reason (manifesto for segregation)

1962: Sherwood Washburn (AAA President)

- Address denouncing Origin of Races at AAA annual meeting  Public  denunciation of ideas seen as necessary

1966: American Association for the Advancement of Science (AAAS) symposium  

- Organized by Margaret Mead and Theodosius Dobzhansky

- Purpose: deliver scientific voice against popular racism

The Bell Curve (1994): Herrnstein & Murray  

- There is a ‘real’ general factor of cognitive ability – human groups differ on  this  

- IQ tests measure this most accurately  

- IQ scores = intelligence  

- IQ tests are not biased  

- Cognitive ability is 40-80% heritable

Positive natural selection: tendency of beneficial traits to increase in frequency in a  population  

- For a trait to undergo positive selection it must:  

o Increase probability of survival and reproduction  

o Be heritable

Purifying selection: removes new deleterious mutations as they arise, rather than  promoting the spread of new traits (also called negative selection)

Selective sweep: when an advantageous mutation arises and is quickly spread,  together with neighboring genetic material in the same region of DNA

Significant selective pressures in human evolution: 

- Changes in diet: milk

o Domestication of plants and animals  provides selective advantage to those who can digest new foods  

o Lactose tolerance/lactase persistence – relatively recent evolutionary  development  

o Can see signatures of differing dietary histories – variation in  populations that can tolerate lactose relates to whether these  

populations had domesticated animals for dairy  

o No support for ‘preadaptation’ hypothesis  

o Different mutations allow lactase persistence in different populations  different ‘solutions’, same outcome

Galactose and Glucose: more easily absorbed into blood stream (decline in  lactase production usually begins by 2 years)

Significant selective pressures in human evolution: 

- Changes in environment: agriculture  

o Increased population density made disease transmission easier  o Likely expanded role of pathogens in natural selection for human traits  o Malaria: major cause of morbidity and mortality, transmitted by  mosquitos that thrive in environments modified by agriculture  

o Malaria pressure favored spread of sickle-cell allele  

o Sickle-cell is an example of balancing selection (selection for the  heterozygous condition)

Significant selective pressures in human evolution:

 Rare mutant allele for CCR5:  CCR5-Δ32

Homozygous: immune to infection

Heterozygous: partial immunity, or delay in onset

- Mutant allele found in ~10% of Europeans; very rare elsewhere  - First wave killed 1/4 - 1/3 of all Europeans  

- Natural selection favored those who by chance had inherited the CCR5-Δ32  gene variant  

- May have also been selected for by other contagious diseases Humans usually respond to environmental stresses with:

Genetic change: when an environmental stress is constant and lasts for many  generations (i.e., sickle cell)  

Developmental adjustment: adjustment to environmental stress occurring during  growth and development, results in changes that are mostly irreversible in  adulthood (i.e., nutritional deficiencies)  

Acclimatization: short-term, long-term – food supply, temperature, altitude (different populations cope differently)  

Cultural practices and technology 

Bergmann’s Rule: Within a species (of warm-blooded animals), populations with  individuals of greater mass found in colder regions and populations with less  massive individuals are often found in warm climates near the equator  

Allen’s Rule: The length of arms, legs, and other appendages also has an effect on  the amount of heat lost to the surrounding environment. Populations in warm  climates tend to have longer limbs than populations living in colder environments

Population: smaller groups within species, temporally and geographically restricted  to some extent; substantial gene flow between them (past and today)

Subspecies: a group of local populations that share part of the geographic range of  a species, and can be differentiated from other subspecies based on a set of  concordant phenotypic or genetic traits

“RACE”: a group of populations sharing certain characteristics that make them  distinct from other groups of populations; often incorporates biological and cultural  criteria

- A typological concept, which assumes that human variation can be classified  into a number of distinct groups through sets of concordant traits

What about underlying genetic variation? 

Lewontin (1972) – tested seven “types”  

- Mongoloid, Negroid, Caucasoid Amerindian, Pacific Islander, Khoi San,  Eskimo/Aleutian

- expected more variation between groups than within them

o 6% of total variation was between groups, 94% of variation was within  them  

Today: genetic variation  

- ~80% within groups, 20% between groups  

- Africans most genetically diverse

Human variation is poorly described by racial  classifications. (main point)

- More genetic variation is attributed to differences among individuals than  among populations  

- Distribution of many traits historically used to define ‘racial types’ is  continuous

- Poor concordance among traits

End of Midterm Review

QUIZLET LINK: https://quizlet.com/_37ho3w

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