ANTH 1 - Exam 1

Subfields (American Anthropology)

- Biological: the study of the evolution of humans and related species as biological organisms; including the study of the relationships between biology and culture

- Archaeology: the study of past cultures through examination of their material remains (artifacts); significantly concerned with the nature and reasons for cultural evolution — overlaps with bio anth and geology but is predominantly a social science

- Linguistic: the study of language in a social context; evolution of language and contemporary usage

- Cultural: the study of current/recent cultural phenomena; studies the evolution of culture

Biology & Culture: Definitions

Biology: refers to the chemical and mechanical processes associated with life.

- Subfields include anatomy & physiology,
genetics, ecology, paleontology, etc. — many of which are directly associated with anthropology


Culture: refers to learned, socially acquired traditions and behavior; symbolic behaviors,

- Anthropologists see culture as being extra-somatic and a choice

Scientific Studies

Attributes:
- Openly defined
- Transparent
- Repeatable
- Based on concrete units of measure

Elements:
- Theory — The broad principles by which an explanation is achieved

- Hypothesis — A proposed explanation for the existence of a specific set of things and/or events

- Method — The way in which a hypothesis/theory is tested

- Conclusions — An interpretation as to whether the data support the hypothesis/theory

Philosophy & The Scientific Method

Philosophy: Science is a way of viewing existence where conclusions must follow logically from relevant and appropriately obtained data

Method: A logical system of results in the intellectual ordering of phenomena

Karl Popper

Pointed out that science cannot prove anything — it can only disprove

ALL scientific knowledge is provisional

New data always has the potential to alter a conclusion

A Priori Conclusions

- Conceived before a study is conducted

- Science is data driven and therefore rejects a priori conclusions

- Most (and arguably all) previous/other comprehensive explanatory systems have been/are based on a priori conclusions

- Science is therefore unique in human history

Aristotle

- Was among the first t posit serious explanations regarding the relationships between living creatures

- Proposed the Great Chain of Being: a ranking of organisms according to their supposed complexity, intelligence, and importance

- Influenced future biological thought whether directly or indirectly

Other Influential Thinkers

Linnaeus: Developed the hierarchal classification system known as taxonomy which classified species based on their physical characteristics — influenced by the "Great Chain" and Christian thought and viewed species as being immutable

Comte de Buffon: Enlightenment thinker that was one of the first serious researchers to propose that species evolved but offered no workable theory as to how this might occur. Also believed that there was a dynamic relationship between organisms and their environments. As well as that Biblical creation was the start of life but that forms evolved after this time — did not believe that species could change into another but that forms degrade. Seemingly non-functional aspects for evolutionary change. Earth was older than Biblical estimates (160k years)

Erasmus Darwin: Grandfather of Charles Darwin. Proposed one of the first structured theories of biological evolution in Zoonomia. Believed that all life had arisen from an original filament and in evolution but offered no specific mechanisms explaining how evolution change comes about.

Georges Cuvier: Opposed the idea of evolutionary change. Proposed the theory of Catastrophism which viewed earlier animal species as being wiped out by a series of natural disasters — these animals were then replaced by stronger, more intelligent, invading species

Jamed Hutton: Geologist that proposed that the "operations of nature are equitable and steady" in Theory of Earth. Refuted catastrophism.

Jean-Baptiste Lamarck: Proposed the Theory of Inheritence of Acquired Characteristics/Lamarckianism. Stated that evolution occurs during the lifetime of a natural organism and did not believe that species went extinct. Was ultimately wrong but arguably the first biologist to understand the profound role of environments in evolutionary processes. Also arguably developed the first coherent theory of biological evolution. Coined the term "biology"

Charles Lyell: Geologist that developed and promoted the principle of uniformitarianism in Principles of Geology. Stated that the same geological processes have occurred throughout all time. Proposed the earth to be much older than dates obtained form Biblical sources (hundreds of million year at least). His ideas set the stage for the emergence of modern evolutionary thought in that the provide an enormously long, time frame in which evolution can occur

Charles Darwin: Sailed the Galapagos Islands on the Beagle. This voyage provided the raw material for Darwin's evolutionary ideas. Developed the concept of Adaptive Radiation which refers to how all Galapagos finch and tortoise species (among others) descended form one single mainland species. They diverged into multiple lineages to meet new local environments. In essence, Darwin believed that species evolved and that given enough time, they could change radically. Natural conditions could produce all the world's organisms. All organisms can trace their ancestry to a single ancestor. Understood that organisms within a species were all slightly different.

Thomas Malthus: Economist that pointed out that organisms can reproduce exponentially, in numbers that are ecologically unsustainable — therefore, not all organisms born can live to reproduce

Alfred Russell Wallace: Independently developed the idea of natural selection.

Binomial Nomenclature

When organisms are referred to simply by their genus and species name (such as Homo sapiens)

Essentialist Thoughs & Populational Thinking

Essentialist Thought: A concept proposed by Plato. Essentialists believe that each organism has a fundamental, unchanging "essence" at its core. Variation within a population is seen as deviations from the perfect essence

Populational Thinking: Rejects essentialist thought. There is no unchanging essence among species. Species are defined primarily by reproductive isolation

Genotype & Phenotype

Genotype: The genetic make-up of an individual organism

Phenotype: An observable or measurable feature of an organism — often used to describe an organism in its entirety, beyond its DNA

Darwin's Dilemmas

Understood the importance of variation between individuals but did not know how this variation was created. Also did not understand the mechanics as to how traits passed from one generation to the next. However, did know that offspring CANNOT simply be a blending of all their parent's traits.

- During his lifetime, some of these issues were resolved by Gregor Mendel, a researcher whose work Darwin was apparently not familiar with

Gregor Mendel

- Worked out the basic laws of heredity by observing the passing on of traits across generations of plants and animals
- Obtained his most useful data through experiments with pea plants

"Mendels Postulates:"
1. Hereditary characteristics (traits) are controlled by particulate unit factors that exist in pairs in universal organisms — offspring get one of these factors from each parent
2. When an individual has two different unit factors only one is expressed and is said to be dominant
3. During the formation of gametes (sex cells), the paired unit factors segregate randomly meaning that each sex cells receives one or the other with equal likelihood
4. During gamete formation, segregating pairs of units assort independently of each other. This is now known as Mendel's Law of Segregation

- Worked the basics of what is known today as genetics solely through observation of phenotypes through generations

Punnett Squares: Demonstrate recessive and dominant genes a.k.a. Incomplete and Co-Dominance — Bb bb Bb bb / PP Pp Pp pp

Mendel's Limitations:
- With pea plants, Mendel chose plants where the traits he was following were controlled by only one gene a.k.a. simple inheritance
- Most traits in complex organisms re controlled by multiple genes making the study of genotype-to-phenotype expression much more complicated than he envisioned
-Genes do not always segregate independently
- In some cases, both traits (alleles) can be expressed — Co-Dominances
- Incomplete Dominance is also possible — the dominant gene does not fully mask the recessive gene's traits, creating an intermediate trait
- Mendel's work does not explain how new genetic variation is created

Polygenic Traits & Pleiotropy

Polygenic Traits — Phenotypic traits that are governed by more than one gene

Pleiotropy — One gene effecting multiple phenotypic traits

Mutations & Events

- Mutation is an "error" (a chemical substitution) that occurs in the replication of Genetic material (DNA)

- Typically neutral to an organism, either because they are not expressed in the phenotype or because the expressed trait neither helps nor hinders the organism's survival though some are detrimental.

- Create new genetic variation

Events:
Random Mutations — Occur through chemical substitution as DNA recreates itself. These have no patterns to them and seem to be a bi-product of the DNA replication process and do not seem to be influenced by outside factors

Induced Mutations — Occur due to the influence of toxins, other chemicals, and radiation. These can cause developmental issues in the phenotype (can occur in gametes and can cause diseases such as cancer when occurring in somatic cells)

Evolutionary Synthesis

Mendel's research was published in an obscure journal and had little impact in his lifetime but was later rediscovered and has been combined with the ideas of Charles Darwin.

This evolutionary synthesis forms the baseline of modern biology

Watson & Crick

Genetics stalled for decades after Mendel's era but major breakthroughs came from geneticist James Watson and biophysicist Francis Crick whom discovered the basic structure of DNA. This worked is viewed as the beginning of modern genetics

Cells & Complex Organisms

Definition: A microscopic entity in which genetic material and other structures are separated from the environment by a semi-permeable membrane.

- Can exist as a single organism or with other cells as part of a complex organism

Types of Cells:
- Prokaryotes — Single-celled organisms without a nucleus (bacteria) — first appeared on earth roughly about 3.5 billion yrs. ago

- Eukaryotes — Cells where genetic material is separated from the rest of the cell by a structure known as a nucleus — First appeared on earth roughly 1.2 billion yrs. ago

All multi-cell life forms are eukaryote based.

Complex organisms are multicellular and sexually reproducing and feature two basic types of cells:

- Gametes — Cells that are directly involved in reproduction

- Somatic Cells — Cells that are not Gametes (all other cells that make up an organism) — Derived from soma which si Greek for body

Mitochondria

Capsule-shaped organelles where metabolic reactions take place resulting in the production of energy-rich molecule (ATP — adenosine triphosphate) that fuels the cell

- Have their own DNA that is not contained in the nucleus and its different from the DNA found in the cell's nucleus

- Were potentially separate prokaryotic cells at some time in their evolutionary history

- Human mitochondria each feature 37 genes

- Hundreds to thousands can be found in a cells (depending on the type of cell)

Endoplasmic Reticulum (ER) & Ribosomes

A complex organelle in the cytoplasm that has a "folded sheet" appearance

- Provides increased surface area for various metabolic reactions to take place

- Rough Endoplasmic Reticulum — An area of the Er with "knobs" called ribosomes

Ribosomes:
- RNA forms a large percentage of the ribosomes

- They serve as sites where protein synthesis takes place

- The information to create proteins (ribosomes) exist in a cell's nuclear DNA

- The synthesis begins in the nucleus but must be completed in the cytoplasm

- Completed ribosomes cannot pass thru the nuclear membrane

DNA — Deoxyribonucleic Acid

- A complex protein that codes for the development of the phenotype — aspects of an organism beyond its DNA

- Contains the information in your body needs to create amino acids (which are combined to make proteins — does this in conjunction with RNA)

- Can replicate itself

DNA Structure:
- The DNA molecule is a double helix

Three major units of DNA (and RNA) are:
- (Nitrogenous) Nucleotide bases (made up of carbon and nitrogen atoms)
- Sugars (deoxyribose in DNA and ribose in RNA
- Phosphates

Nucleotide Units and Bases:
- The DNA molecule has four different nucleotide units featuring different bases — humans have around 3 billion nucleotides

There are two classes of bases:
- Purines: Adenine (A) and Guanine (G)

- Pyrimidines: Cytosine (C) and Thymine (T)

A purine always bonds with pyrimidine and vice-versa

- Adenine always bonds with Thymine (AT)

- Cytosine always bonds with Guanine (CG)

They are held together by weak hydrogen bonds which can be easily broken

DNA is unusual in that it is stable in all potential forms which is not the case with many other molecules

NO possible base sequence is unstable
- This also makes it an excellent vehicle for transferring genetic information between generations

DNA Replication:
- Mitosis — Somatic cell division in which a single cell divides to produce two daughter cells

- Meiosis — Cell division that only occurs in the testes and ovaries that leads to the formation fo sperm and ova, which combine to create gametes

DNA replication can only affect heredity if it occurs in the gametes

Genetic Code

The information to make proteins (amino acids) is contained in the sequence bases of the DNA molecules

- The part of DNA molecule that contains for one polypeptide chain (a protein) is called a gene

- One gene can feature hundreds of thousands of bases and humans have between 20,000-25,000 genes (there can be more in some cases)

Codons

Nucleotide bases code for proteins in groups of three. These three-base sequences form a single amino acid.

- There are 64 possible codons and only 20 amino acids

- Most amino acids are represented by more than one codon

Termination codons do not code for an amino acid but instead signal that a protein chain has come to an end where as Initiation codons signal the beginning of a polypeptide chain (also represents the amino acid methionine)

Transcription & Translation

The information is "transcribed" from the DNA to the RNA

The mRNA then separates (upon which the DNA molecule closes) and carries the information from the nucleus to the cytoplasm, where protein synthesis (translation) eventually occurs.

- Protein synthesis occurs at the ribosomes (on the Rough ER, in the cytoplasm)

Note: A single mRNA molecule can be read by several ribosomes at the same time which means several copies of a protein can be made from one transcription/translation

Exons & Introns

When the mRNA returns to the cytoplasm it is subject to Post-Transcriptional Processing through bonding with transfer RNA (tRNA)

Sequences of the mRNA are spliced out and the molecule is reassembled

Introns are NOT expressed in a protein whereas Exons are

Coding and Non-Coding DNA

In humans, only 3% is coded for protein synthesis

- Most human DNA is non-coding DNA

- Roughly 80% of non-coding DNA serves in gene regulation

Gene Types

Structural Genes — Determine physical characteristics (of the phenotype)

Regulatory Genes — Regulate the effects of other genes

Chromosomes

Most of the time, DNA exists in uncoiled strands, a state called chromatins

- During mitosis or meiosis, the DNA tightly coils itself into structures called chromosomes.

(Each somatic cell in a person's body has the same number of chromosomes)

Most organisms have two copies of each chromosomes in each cells (one from each parent)

- The total number of chromosomes in a cell is called the diploid number

- Gametes have only half the number of chromosomes, which is known as the haploid number

- In a diploid cell, the members of each pair of chromosomes are known as homologous chromosomes

- Genes are distributed across the chromosomes — A gene is also known as locus (plural loci)

- Somatic cells also have two copies of each gene which are called alleles.

When a person has the same allele (trait) at each locus on each chromosomes they are called homozygous for that gene

- If there are different alleles at each locus of each chromosomes a person is called heterozygous for that gene

Humans have 23 chromosomes (haploid — 45 diploid)

In mammals, sex chromosomes are labeled as X (female) and Y (male)

- Females = XX
- Males = YX

Mitosis & Meiosis

Mitosis is the basis of cell creation
- it occurs during the growth of an organism, during healing, or other times when cells need to be creates

Meiosis occurs in the tests and ovaries
- leads to the formation of gametes, which have a haploid number of chromosomes

When sperm and egg unite to create a zygote (fertilized egg), the diploid number of chromosomes is established

Crossing Over:
- double-stranded homologous chromosomes team up, forming units made up of four chromatids (threadlike strands)
- The strands then send genetic material across to the other strand, creating new DNA combinations

(does NOT create new genetic material — any mutation would have had to occur prior to this point)

Epigenetics

Refers to the environmental factors creating an inheritable trait with no change in DNA structure

- Occurs through methylation — the attachment of a methyl group to an area of the DNA molecule

(Methyl is a simple chemical that had many functions in the human body, including the regulation of gene expression)

- This can cause changes in the way genes are expressed or cease their expression in the phenotype

- Factors causing these processes are chemical exposure, radiation, nutrition, and even stress

- This field of study is in its infancy and many of the specific cues and outcomes of methylation are not yet well understood

Race & Subspecies

Race: Refers to the division of humans into groups based on biological characteristics; the human equivalent of the subspecies concept developed by biologists mainly to classify non-human life

Subspecies: Refers to local populations that share part of the geographic range of a species and can be differentiated from other subspecies by one or more phenotypic traits

The "Naked Ape"

Humans have become largely hairless (compared to other primates) in part response to heat dissipation needs — shoutout to sweat lol (it's efficient)

Melanin

The relative lightness or darkness of the skin is largely determined by the amount of melanin, (polymer pigments derived from amino acids)

- Melanin protects the skin from the sun in proportion to its abundance so the more melanin one's skin contains, the darker one's skin

However, melanin also reduces the photochemical reactions that lead to the creation of vitamin D

Environments & Skin Color

The more humans are exposed to the sun the greater the opportunity their bodies have to synthesize vitamin D

- Humans with higher degrees of sun exposure can afford to have relatively dark skin because there is so much potential for vitamin D synthesis

They also need dark skin to be protected from the sun's damaging effects

- Selective advantages in these environments would go to those with relatively dark skin

In colder, darker environments, there is less potential for vitamin D synthesis because there is less sunlight. Therefore the skin needs to do more work and melanin hinders this process. This environment also created a lesser need for melanin because the skin is less subject to damage because of the relative weakness of the sun.

- Selective advantage in these environments would go to individuals with relatively fair skin

Diet also plays a part in skin color.
- Human groups with regular access to vitamin D-rich food sources often have dark skin than would be predicted by their latitude
- Coastal people often fall into this category because of seafood resources are generally rich in vitamin D

Sun Exposure

Lack of body hair exposes skin to damage by the sun, through ultraviolet radiation (folate breakdown)

- The loss of vitamin B folates can create problems in humans in many areas, such as reproduction

Genetic Drift — Continued

Early in human history, populations in many parts of the globe were very small in numbers and for long periods of time (relatively) isolated from other human groups. This means that genetic drift has likely played a significant role in the way humans appear today

Founder(s) Affect:
- Founder populations would not have carried the full genetic compliment of the groups off of which they had split and because of this, certain traits would have been over or under-represented

- Traits with (little or) no selective value would have proliferated, creating relatively minor differences in appearance between the descendants of the founder population and their descendants of the original population

Cultural Attributes

Can affect biological evolutions

- For example, the wearing of clothes (and spending a lot of time indoors) means less skin is exposed to the sun

- In cold climates, humans tend to wear more clothing and spend more time indoors, leaving less of their skin exposed to the sun

This means exposed skin must be able to take in even more vitamin D, prompting the selection for even fairer skin (e.g. Fennoscandia)

Bergmann's Rule

- Large (more stout and round) body sizes should evolve in colder climates to conserve body heat

- Limbs will be shorter

- Relatively short bodies are favored

- Bodies also evolve to store more subcutaneous fat in these climates

Allen's Rule

- In warmer climates the limbs are longer relative to body size (this helps dissipate heat)

- Peoples in these climates are often very tall and thin with very long arms and legs

- Feature relatively little subcutaneous fat

Ethnicity

This term has been developed in recent decades and is largely replacing "race" (at least in the sciences and humanities)

- Refers mostly to culture, while acknowledging biological differences between groups

Hypoxia

Hypoxia:
Oxygen content in the atmosphere lessoning with altitude

- Populations living for long periods in high altitudes have evolved in ways in which their body can circulate blood and oxygen through their systems more efficiently than other humans

- People from the Himalayas and to a lesser extent, those from the high Andes have evolved such traits

- Those without such traits living in such environments for sustained periods can develop hypoxia, a condition where the body cannot take in enough oxygen to function properly.

Short term symptoms include: headaches, dizziness, and nausea.

Long-term hypoxia can lead to severe damage to the heart, lungs, and brain

Sickle-Cell

A trait that occurs through the expression of a recessive gene, leading to sickle-cell anemia

- Changes the shape of red blood cells in a manner that makes it difficult to impossible for them to circulate through the body

It can lead to severe health problems and even daht

- It is very common in Africa (where at least the modern strains of malaria seem to have developed) and much less so in parts of Asia

Sickle-Cell Traits & Malaria
The recessive gene that leads to sickle-cell anemia is maintained in human populations because it is favored as a (balanced) polymorphism

- Individuals who inherit this trait from only one parent are resistant to malaria and these individuals have slightly smaller red blood cells, which are less optimal hosts for the mosquito-spread parasite that causes the diseases

Today, malaria is most common in tropical and subtropical zones however, the sickle-cell trait is generally common in sub-Saharan Africa and in populations who trace their (relatively recent) ancestry to this part of the world

African-American communities have a higher percentage of sickle cell anemia than most sub-Saharan African groups. This is because of their smaller populations, which means this recessive trait is more likely to be expressed.

- Has been greatly amplified due to racism and white ethnocentrism

- Has kept their gene pools from blending these continent's populations to the same degree as other groups

Lactose Intolerance

Milk products contain a sugar called lactose and in order to digest this, mammals need a protein called lactase. Most mammal's bodies produce this protein when they are young so they can digest their mother's milk and as they are weaned, their bodies cease production to lactase.

- Humans follow this pattern, generally. However, groups that evolved in pastoralist or sedentary agricultural societies that emphasized milk-producing animals have evolved to produce lactase into adulthood.

- Most adult humans today are lactose intolerant to some degree

TEXTBOOK — Terms

Heteroplasmic — Refers to a mixture of more than one type of organellar DNA, such as mitochondrial DNA, within a cell or a single organism’s body, usually due to the mutation of the DNA in some organelles but not in others.

Karyotype — The characteristics of the chromosomes for an individual organism or a species, such as a number, size, and type. The karyotype is typically presented as a photograph of a person’s chromosomes that have been arranged in homologous pairs and put in numerical order by size.

Patriline — DNA whose inheritance can be traced from father to son via the Y chromosome

Matriline — DNA, such as mitochondrial DNA, whose inheritance can be traced from mother to daughter or to son

Haplotypes — A group of alleles that tend to be inherited as a unit due to their closely spaced loci on a single chromosome

Haplogroups — A large set of haplotypes, such as the Y chromosome or mitochondrial DNA. that may be used to define a population

Translocation — Rearrangements of chromosomes due to the insertion of genetic material from one chromosome to another

Nondisjunctions — Refers to the failure of the chromosomes to properly segregate during meiosis, creating some gametes with abnormal numbers of chromosomes

Monosomy — Refers to the condition in which only one of a specific pair of chromosomes is present in a cell's nucleus

Trisomy — Refers to the condition in which an additional chromosome exists within the homologous pair

Microevolution — Small-scale evolution, such as changes in allele frequency, that occurs from one generation to the next

Macroevolution — Large-scale evolution, such as a speciation event, that occurs after hundreds or thousands of generations

Spontaneous Mutations — Random changes in DNA that occur during cell division

Induced Mutations — Refers to those mutations in the DNA resulting from exposure to toxic chemicals or to radiation

Mutagens — Substances, such as toxins, chemicals, or radiation, that may induce genetic mutations

Antigens — Specific proteins, on the surface of cells, that stimulate the immune system's antibody production

Antibodies — Molecules that form as part of the primary immune response to the presence of foreign substances, they attach to the foreign antigens

Cline — A gradual change in some phenotypic characteristic from one population to the next

Balanced Polymorphism — A situation in which selection maintains two or more phenotypes for a specific gene in a population

Functional Adaptions — Biological changes that occur during an individual's lifetime, increasing the individual's fitness in the given environment

TEXTBOOK — People

Robert Hooke — Scientist that studied the microscopic structure of fossil wood. After observing that the tissue structure of the fossil wood was identical to the same tissue structure of living trees, Hooke concluded that the fossil wood derived from once-living trees; pioneered microscopy.

- Proved that fossils are organisms' remains and revealed that fossils would provide the history of past life


Thomas Henry Huxley — A biologist that was known as "Darwin's Bulldog" for forcefully promoting Darwin's theory of evolution by natural selection. Among Huxley's contributions was the concept that humans evolved from apelike animals.


Hardy—Weinberg — Godfrey Hardy, a mathemetician, and Wilhelm Weinberg, an obstetrician independently recognized that some alleles are in a state of equilibrium. Simply, a single locus has A (dominant) and a (recessive) alleles, with respective frequencies of p and q. In assessing the population as a whole, it is assumed that males and females have both alleles.

- The Hardy-Weinburg law predicts the genotype of frequencies for the next generation after one mating where p2 is the genotype frequency for the AA homozygous alleles, 2pq is the genotype frequency for the Aa (heterozygous) alleles, and q2 is the genotype frequency for the aa homozygous alleles.

(The total population (100%) should be the sum of the frequencies of three genotypes expressed by the simple mathematical equations p2 + 1pq + q2 = 1. If a hypothetical population where 60% A (p = .6) and 40% a (q =A), then the genotype frequencies in the next generation would work out to AA = .36, Aa = .48, and aa = .16.

In essence, the Hardy-Weinberg equilibrium hypothesizes that gene frequencies remain the same because no evolutionary change takes place. The Hardy–Weinberg equation establishes expectations as to whether evolution is operating on a particular gene. If the genotype frequencies change from one generation to the next, the population is not in equilibrium—it is evolving. If frequencies remain the same, the population is in equilibrium and is not evolving, at least with respect to the locus being studied.