Bio-Anthro196 Midterm

Four Fields of Anthropology

Cultural anthropology, biological/physical anthropology, archaeology, and linguistic anthropology

Fixity of Species

Species as immutable and never changing

The Great Chain of Being

A ladder system from Aristotle in 4th cent. bce that says the bottom is the least complex and the top is most (humans only outranked by angels/deity)

Archbishop James Ussher 1625-56

Idea of a grand design and “full earth” ; discovered that earth was created in 4004 bce (theory made sense at time b/c of little evidence)

1500s-1700s as an Era

Investigation of natural world with new discoveries

1500-1700s New Discoveries

Circumnavigation (slight differences found), fossil finds (of animals they know don’t exist), and discovery of the new world (people live there already)

Culture

Set of learned behaviors shared by a group of people defined by their common past

Evolution 

Biological = change in genetic structure of a population over time / change in allele frequency from one generation to the next

Main Steps to Humanness

• Bipedalism (walking on two feet)

• Non-honing canine (change in teeth)

• Material culture/tools (reliance on culture)

• Hunting (social/brain development)

• Speech (communicating)

• Dependence on domesticated food

Early Evolution Theory Natural Scientists

Carolus Linnaeus, Erasmus Darwin, Jean-Baptiste Lamarck, Georges Cuvier, Charles Lyell

Carolus Linnaeus (1707-78)

Binomial nomenclature : genus species (2 name system of naming) with an inclusion of homo sapiens

Taxonomy

System of classification of biological world

Taxonomy Today

• Gives science a common language 

• Illustrates relationships

Taxonomy of Humans

Kingdom - Animalia

Phylum - Chordata (spinal cords)

Class - Mammalia

Order - Primates

Family - Hominidae

Genus - Homo

Species - Sapiens 

Biocultural Approach

The holistic framework in anthropology that emphasizes the interconnectedness of biology and culture 

Erasmus Darwin

The grandfather of Charles Darwin who wrote prose about evolution : everything evolved from microscopic organisms in the sea

Jean Baptiste Lamarck

Gave us the term biology and attempted to explain evolution ; body must sense a “need” or “want” that directs “fluids” or “forces”

Lamarckism

Inheritance of acquired traits / use-disuse theory

Example of Lamarckism

A giraffe using neck to reach for food causes it to increase in size that’s then passed onto offspring (wrong)

Georges Cuvier

Opposed Lamarck and believed in catastrophism (biblical flood) that lead to extinction (fixity of species)

Charles Lyell

Father of modern geology that believed  in uniformitarianism (from Hutton) and deep time (long time scale for his processes)

Charles Darwin

Interested in natural world as a child and studied such topics in adulthood and who began ideas of natural selection on his voyage of the beagle

The Voyage of the Beagle

Journey Darwin went on after flunking out of college and becoming a priest; he became ship’s naturalist; studied Lyell’s “principles of geology” and looked at galapagos finches as an example of uniformitarianism (beak formation connected to food eaten)

Adaptive Radiation (Darwin)

Radiating outwards with adaptations 

Artificial Selection to Darwin

Humans = selecting agents (domesticated animals)

Who was Darwin Influenced by?

Malthus (father of demography) who said populations are limited by their food supply

AR Wallace

Published a paper in 1855 about transmutation with a change of one species to another (natural selection) and sent the paper to Darwin (20 years after Beagle voyage)

Darwin’s “On the Origin of Species” + Natural Selection

• Variation

• More individuals are produced than can survive; competition

• Environment decides what’s favorable : selective pressure

• Individuals with favorable traits survive and reproduce (reproductive success and fitness)

Difference Between Natural Selection and Evolution

Natural selection operates on individuals while evolution occurs in populations

Fitness

Differential Reproductive Success

Key Points of Natural Selection

• Trait must be inherited if natural selection works on it

• There must be a variation in inherited traits (selection only works on traits that already exist)

Darwin’s Mode of Inheritance

Gemmules - invisible particles

Blending inheritance - offspring will be a blend of parents

Gregor Mendel’s Mode of Inheritance

Unit of heredity: genes

Alternate forms: alleles - comes in pairs ; one from dad and one from mom

Genotype: genetic makeup of individual - genetic code

Phenotype: Actual observable trait - physical

Dominant: alle that masks expression of other allele vs recessive

Mendel’s Experiment 

What hybrids would result from breeding two purebred plants?

Mendel’s Principles

Principle of segregation and of independent assortment

What does Mendel’s Work do for Evolutionary Synthesis

Forms the basis of genetics - unified theory that combines genetics with natural selection

Prokaryotes

Usually single celled and no nucleus (single strand chromosome)

Eukaryote

Single or multi-celled with nucleus; structurally more complex 

Two types of eukaryote cells

• Somatic cells : cellular components of body tissues

• Gametes : sex cells involved in reproduction - sperm and ova (haploid) that fuse to form a zygote

mtDNA

DNA found in mitochondria and only from mother

DNA

Responsible for genetically inherited traits (genome = genetic makeup), cellular functions, and protein synthesis

Nucleotide

Sugar, phosphate, and nitrogenous base - purine (adenine, guanine) and pyrimidine (thymine, cytosine)

Complementary Base Pairing

Nitrogenous bases pair predictably (A to T and G to C)

Protein Synthesis

• DNA codes for proteins 

• Proteins are made up of amino acids

• 3 base pairs (codons) for 1 amino acid

• 20 amino acids 

• Protein examples: hemoglobin and enzyme

Genes

Sequence of DNA that codes for a specific protein - not all segments of DNA are expressed

Transcription

Occurs in nucleus, DNA strand unravels, mRNA - one stranded complement of DNA (messenger)

Difference Between mRNA and DNA

• single stranded

• different type of sugar

• contains base uracil (no thymine)

Translation

mRNA travels to ribosome after transcription (translated) and tRNA attaches proper amino acids, creating a polypeptide chain (chain of amino acids)

Structural Genes

Produce proteins responsible for morphology

Regulatory Genes 

Produce proteins that control timing of processes and development 

Chromosomes

• How DNA is packaged

• Occurs in pairs : homologues chromosomes

• Location of a gene: locus

Alleles

Alternate forms of gene: homo and heterozygous

Autosomes 

Determine all morphology, except sex determination: 44 in humans and 22 pairs 

Sex Chromosomes

Determine sex = 1 pair in humans ; XX in females and XY in males

Somatic Cells

46 total chromosomes; 23 pairs; 44 autosomes and 2 sex cells (half from mom half from dad)

Diploid Cell

2 sets of chromosomes (pairs

Gamete Cells

23 total chromosomes no pairs (22 autosomes and 1 sex chromosome)

Haploid Cell

1 set of chromosome (no pairs)

Mitosis

Somatic cells where 1 cell divides into 2 cells with 46 chromosomes each

Result: 2 identical diploid daughter cells 

Meiosis

Gametes with two cell divisions

1st division: 1 cell divides into 2 diploid cells

2nd division: 2 resulting cells divide into 2 haploid cells each

Result: 4 nonidentical haploid cells

Crossing Over in Meiosis

Homologous chromosomes overkao and exchange genetic material (recombination) and redistribute variation but don’t create new alleles

Problem with meiosis

Nondisjunction: failure of homologous chromosomes to separate (ex: down syndrome)

Polymorphisms

The presence of 2 or more phenotypes for a certain gene (frequencies greater than 1%)

Simple (Mendelian) Traits

Only two alleles (recessive/dominant) and discrete (presence/absence)

Examples: albinism and PTC tasting

Complex Traits

Continuous distribution, not completely recessive/dominant, and influenced by the environment

Example: Height, eye color, hair color, etc.

Polygenic 

Single trait controlled by two or more genes 

Pleiotropy

Single gene influences multiple traits

Heritability

Proportion of total phenotypic variability observed for a given trait that can be ascribed to genetic factors

Deme

Small, localized population of interbreeding individuals that forma distinct unit within a larger species

Gene Pool

Genetic information in reproductive populations

Species

All populations that can be interbred and make fertile, viable offspring

Reproductive Isolation

Prevents 2 populations from interbreeding and can lead to speciation (creation of new species)

Microevolution

Occurs within a species

Macroevolution

Occurs between species (speciation) 

Example: emus and ostrich’s becoming genetically distinct

Natural Selection with Simple Traits

• Two phenotypes (dom/recess and discrete)

• Three genotypes (homozygous dom = TT ; heterozygous = Tt ; homozygous recessive = tt)

• Acts on the phenotype (either against dom or recessive)

Balancing Selection

The heterozygous condition is favored as homozygotes are selected agains

Ex: Sickle cell anemia w/ HbS or HbA : HbS x 2 is sickle cell anemia ; HbA x2 is normal red blood cells ; HbS and HbA is sickle cell trait with some effect

Natural Selection + Complex Traits: Stabilizing

Selection for the mean (ex: birth weight and clutch size of robin’s and eggs)

Natural Selection + Complex Traits: Directional

Selection against one extreme (ex: finch beak size and peppered moths)

Natural Selection + Complex Traits: Disruptive

Selection against the mean ; very rare and may result in speciation (ex: hypothetical rabbit coat color)

Sexual Selection

A type of natural selection where females choose males with preferred traits (ex: peacocks + peahens)

Genetic Drift

A random change in allele frequencies with a greater effect on smaller populations ; can cause an allele to become fixed

Founder Effect

Type of genetic drift with a mother population going to a new population (ex: amish babies having six fingers)

Mutation

Changes in base pair sequence of genetic material (DNA or RNA) that can change an amino acid and protein

• Can be rare/random and good/bad/neutral

• The ONLY new source of genetic material

Point Mutation

Replacement (synonymous point mutation doesn’t change the amino acid)

Frameshift Mutation

Can be insertion or deletion that shifts the rest of the code and changes the amino acid/protein

Spontaneous Mutation

Copying errors during cell division

Induced Mutation

Radiation, chemical mutagens, and viruses

Heritability of Mutation

Must be present in the gametes

Gene Flow

Movement of alleles from one population to another where new genes are introduced but not created (opposite = inbreeding with too little gene flow)

Gene Flow Cline

Gradient in allele or trait frequency across a geographic area, shaped by the balance between gene flow, (which tends to homogenize populations) and other forces like natural selection (which promote differentiation)

Hardy Weinberg

A theory of genetic equilibrium with a mathematical model that assumes evolution isn’t occurring (null hypothesis compared to others)

Assumptions of Hardy Weinberg

• Population is infinitely long

• No mutation is occurring

• No gene flow

• No natural selection

• Mating needs to be random with an equal number of males and females for breeding

Hardy Weinberg Formulae

p2 + 2pq + q2 and allele frequencies: p + q = 1

Blumenbach’s 5 Races

Mongoloid (yellow), american (red), caucasian (white), malayan (brown), and african (black)

Eugenics in Early 1900s America

USA legalized forced sterilization that targeted disabled and marginalized populations

Franz Boas

Debunked race concept with anthropometric data from 18000 immigrants and their kids shows skull and body shape/size are plastic

Modern Racial Concepts

Based on few physical characteristics (biological determinism) and are mostly social/cultural and fluid ; Human variation as clines - not distinct

Richard Lewontin on Race

Not a biological reality as there’s more variation within groups than between them

Genetic Diversity Statistic

Fst

Fst of 0

Two populations consist of individuals who share exactly the same alleles at the same frequencies