anthropology 1 midterm

anthropology

the study of humans; culture, biology, artifacts, past and present day

Human evolutionary biology (biological anthropology)

Studies the past and present genetic/biological differences in humans and how humans compare to non-human primates

Charles Darwin

Most famous scientist to discuss evolution. He fleshed out the idea of evolution and provided more evidence for it than other contemporizes or older ideas. Looked at evolution by natural selection

Alfred Russel Wallace

Scientist from the same time period as Darwin who independently came up with a similar theory of evolution.

Nasir al-Din al-Tusi

One of the first people to discuss biological evolution in the 1200s.

Ibn Khaldun

Another early thinker who talked about the idea of evolution in the 1300s.

Jean-Baptiste Lamarck

Wrote one of the first books on evolutionary biology in 1809. He believed that evolution was progressive and had a goal of complexity.

Evolution

Change in frequency of traits/alleles through time

Pace

at what rate is evolution occuring

stasis

when evolutionary processes are not acting and traist remain unchanged

gradual

steady evolution over time

punctuated

sharp changes followed by stasis

Branching

evolution can take different paths which can cause the creation of new species or subspecies

Progressive change

the incorrect idea that evolution always has an end goal and will continuously create more complex organisms over time

Darwin’s 1st postulates

Over reproduction: not enough resources for all members of a group

Darwin’s 2nd postulate

Individual variation: members have variation between them and this variation effects their ability to survive/reproduce

Darwin’s 3rd postulate

Variation is inherited: variation can be passed down to offspring, there is a genetic component to the trait.

Natural selection

an evolutionary process which favors traits that maximizes inclusive fitness

Adaptation

a trait (physical or behavioral) that is well-suited to an organisms circumstances (i. e. environment, predators, social group)

Directional selection

a type of natural selection which favors one side of the average, shifting it over time.

Stabilizing selection

a type of natural selection where the average is favored; happens when environment is “stable”

Disruptive selection

a type of natural selection that favors both extremes and not the average; can create speciation.

Complex adaptations

complex adaptations emerges step by step where all steps increase reproductive success.

Variation

a difference between individuals

Blending inheritance

the old and incorrect theory that thought children were a “blend” of their parents characteristics

Mendel’s first law

Law of segregation: characteristics of organisms are determined jointly by two “particles”, one inherited by each parent. “Particles'“ are carried on chromones and are stretches of DNA called genes.

Alleles

variants of genes

Genes

a stretch of DNA on the chromosome

Mendel’s 2nd law

Law of independent assortment: “particles” for different traits are independently inherited (don’t have anything to do with each other)

Chromosomes

long strings of DNA wrapped around proteins to make them compact; they’re a way to organize and store your DNA. They are found in pairs in cells.

mitosis

the process where a cell divides to create two genetically identical daughter cells

meiosis

the process of cell division in sexually reproducing organisms that reduce the number of chromosomes in gametes. In humans, you get one set of chromosomes from each parent.

Phenotype

observable traits of an organism

Genotype

genetic traits of an organism

Dominant trait

the specific version of a gene that hides/over rules the effect of another version. The dominant trait will be reflected in the phenotype.

Codominant

when there is an intermediate expression of two genes.

locus

a spot on a chromosome

Crossing over

when genes on the same chromosome get tangled and break during meiosis

Recombination

genes are on different spots on the chromosome because of crossing over

Linked genes

genes that are close together on the same chromosome and tend to be inherited together

Hardy-Weinberg equilibrium

populations will remain at equilibrium when there are no evolutionary process acting on it and when mating is random with respect to genotype. IRL evolutionary processes are always happening.

Random mating

when an individual is equally likely to mate with another in the population, regardless of genotype

Population genetics

field of biology that uses math models to study evolution

continuous distribution

when there are not hard categories for a trait to fall into

human height is ___ distributed

normally distributed

40% of human height variation can be predicted by….

12,111 genetic loci or knowing parent height

why does knowing parent height allow us to predict 40% of variance in height?

Parents represent all alleles that determine height and are likely in the same environment as their children.

human height is caused by…

many different loci

Reproductive success (fitness)

an organism’s ability to pass on genetics to the next generation through offspring

Reproductive success is based on…

survival, access to at least one mate, how many offspring are produced each mating, and whether the offspring survive to adulthood

Sexual selection

a form of natural selection that favors traits that provide benefits for breeding; can be harmful to individual survival

Sexual dimorphism

phenotypic (e.g. size) and/or genotypic differences between individuals of different sexes of the same species.

Female sex

Big gametes (egg)

Male sex

small gametes (sperm)

Naturalistic fallacy

The incorrect assumption that because something happens in nature it is good or that since something happens it should happen or that describing something is not prescribing something.

Intersexual selection

favors traits that make males more attractive e.g. phenotypic benefits like protectiveness, resources, social support, genotypic benefits like color, display, and condition, and arbitrary traits females prefer.

Intrasexual selection

favors traits that make males successful in competition

Scramble competition

Form of intrasexual selection where males are trying to get access to females first.

Sperm compition

a result of scramble competition that increase sperm production and or sperm quality so a male’s sperm gets to the egg first.

Contest competition

males compete with each other for females, can cause sexual dimorphism where males have larger bodies, weapons, costly signals, and aggressive behavior.

Altruism

Acts that are costly to self but help others

Coefficient of relatedness

proportion of alleles an individual shares with another individual (e.g. full siblings are .5)

Hamilton’s rule formula

B (benefits for recipent) x r (relatedness) > C (cost to indiviual)

Hamilton’s rule words

Altruistic acts will be favored by natural selection (kin selection) when the benefit to recipient and relatedness is greater than the cost to individuals. Cooperation will only evolve in groups which individuals are related to each other.

Inclusive fitness

Fitness is not only determined by how much reproduction an individual does, it is determined by both direct and indirect fitness.

Direct fitness

One part of inclusive fitness that is individual reproductive success

Indirect fitness

One part of inclusive fitness that is the reproductive success of other individuals that share genes with an individual (relatives)

Neutral processes of evolution are…

Mutation, genetic drift, and gene flow.

Mutation

Change to DNA sequence that can be pasted on to offspring if it occurs in a cell on a path to becoming a gamete.

Mutation are usually…

uncommon because they are normally corrected by DNA repair mechanism

Mutation are mostly…

harmful or neutral

Genetic drift

Chance changes in allele frequencies in population that is finite in size because gametes happen to combine to form zygotes and individuals happen to have more offspring.

genetic drift ___ variation

reduces because one allele can reach “fixation” by genetic drift.

Founder effect

Strong genetic drift that occurs when a group is formed from only a few ancestors.

the found effect makes groups more ___

different

Gene flow

Exchanging alleles between and withing groups

Gene flow makes groups more ___

similar

Mutation and genetic drift can ___ if they occur at the same time

balance each other out. Variation is lost by genetic drift but added back by mutation.

Mutation and genetic drift within a group makes…

equilibrium

mutation and genetic drift between groups makes…

increased differences

Constraints on adaptation

correlation, local optimums, and genetic drift

Correlation

one gene affects multiple traits e.g. mammals almost always have 7 neck vertebrae; mammals with more tend to die before birth. 7 vertebrae are correlated with development.

Local optimum

natural selection is “blind” sometimes it reaches a good solution, not the best solution e.g. whales have lungs instead of gills.

Genetic drift constrains adaptation because…

natural selection is constrained by available variation, and genetic drift deceases variation.

Neutral evolutionary process will make those within larger groups more…

different

neutral evolutionary process will make those in smaller groups more…

similar

DNA

a series of base pairs and sugars that carries the genetic instructions for function, growth, and reproduction

DNA base pairs

Cytosine (c), Guanine (g), adenine (a), and thymine (t)

RNA

single-stranded molecule that acts as the in-between for DNA and proteins.

Intron

the part of RNA that is removed during the process of creating proteins

Exon

the part of RNA that is kept during the process of creating proteins

Genetic distance

a measure of how different two groups are

How to measure genetic variation?

“classical” markers and SNPs

“Classical” markers

blood groups, protein polymorphisms, short tandem repeats (STRs)

blood groups

individuals differ in protein found on the surface of red blood cells

protein polymorphism

different DNA bases result in different amino acids, which combine into different proteins; therefore, protein variation reflects underlying DNA variation.

STRs

Short DNA sequence is repeated multiple times; individuals are polymorphic in the number of repeats.

SNPs

position in the genome for which individuals differ in which base is present.

mitochondrial (mt)DNA

short DNA molecules outside of the cell nucleus. Can only trace maternal lines of decent because it is inherited only from the egg.

X chromosome

chromosome inherited from your mother