ANT 1 FINAL

What is anthropology

present-day human societies, cultures, languages, genetics and past societies, archaeology, extinct hominins, non human primates

what is human evolutionary biology?

study of processes governing human evolution

which species are more closely related?

humans and chimpanzees

phenotype

observable characteristics of an organism

life histories

together, the age, size, or stage specific patterns of development, growth, maturation, reproduction, survival, and lifespan define an organism’s life cycle aka its life history

microevolution includes

inheritance and mating

macroevolution includes

how, when, and why did differences between humans and our common ancestors with chimpanzees/bonobos arise during the past 7 million years

macroevolution includes pt 2

species and speciation, primate diversity, ecology, life history and social systems, human evolution and speciation

how much genetic variation is in humans

87%

how much genetic variation is between chimpanzees?

77%

how much genetic variation is in orgautans?

66%

the terms evolution and natural selection are interchangeable

false

scientists have directly observed natural selection in populations of wild animals

true

evolutionary processes inevitably produce organisms that are more complex than their ancestors

false

natural selection can favor traits or behaviors that make an organism less likely to survive

true

natural selection primarily acts for the good of the social grouo

false

what is evolution visible to the naked eye?

macroscopic, change in heritable phenotypic characteristics over successive generations

what is evolution at a small scale

genetic changes (dna sequence) or cultural changes happening over successive generations

is blending inheritance accurate?

false, 19th century scientists believed that each person was a blend of their offspring but studies show that each generation is not as uniform as the one before as previously thought

who was the founder of genetics, discoverer of principles of inheritance

gregor mendel (1884-1922)

what was mendel’s pea experiment

took seeds with 2 forms, green/yellow seeds, smooth/wrinkled seeds, cultivated true breeding lines, studies results of crosses

what was mendel’s f0 generation and their offspring?

cross green and yellow parents (f0), all offspring were yellow (f1 gen)

what was mendels f2 generation

crossed f1 generation, f2 generation gave a 3:1 ratio of yellow to green. yellow is dominant.

what about mendel’s trait pairs?

mendel’s laws of inheritance

characteristics of organisms are determined jointly by two particles, particles for different traits are independetly inherented (Independent assortment), and some particles are more dominant over other particles (yellow over green)

what are cells?

cell contains a nucleus, nucleus contains chromosomes, chromosomes are paired in our species, 23 pairs in humans

what is mitosis?

when somatic (normal body) cells divide, chromosomes are doubled. each daughter cell has the same paired chromosomes like the original cell

what is meiosis?

gametes (aka ovum and sperm) are formed by meiosis, cell division results in only 1 copy of each chromosome, gametes then fuse (thru sexual reprod.) and create a zygote with a full set of paired chromosomes.

mendel’s law + discoveriies in genetics

Characteristics of organisms determined jointly by 2

“particles”, one inherited from each parent

‣ Mendel’s “particles”

• Carried on chromosomes

• Gametes carry single copies of parental

chromosomes, so only 1 “particle” from each

pareny

what are chromosomes?

chromosomes composed of dna, mendel’s particles are stretches of dna called genes, variants of gene are called alleles

why was mendel lucky?

The traits he studied were determined by a single gene

• But in reality, most traits are produced by many genes

acting together!

• One allele was completely dominant over the other

• But in reality, there is often “codominance” where

heterozygotes have intermediate phenotypes

• Both genes were independent (hence the 9-3-3-1 ratios)

• But in reality, genes are often linked (it happens when

they are on the same chromosome

where are genes located?

genes for a particular trait occurs at the particular site (locus) on the chromosome, loci are lined up like beads on string

what is crossing over (genes and chromosomes)

Chromosomes tangle &

break during meiosis

‣ Bits can be swapped

between paired

chromosomes

• Called crossing over

‣ The closer together two

loci are, the more likely

they are to stay together

hardy-weinberg relationship (1908)

Describes consequences of sexual reproduction &

random mating on allele & genotype frequencies

1. Allele frequencies don’t change between generations

2. After one generation of random mating genotype

frequencies stay constant – an equilibrium value for

genotype frequencies is reached

3. At equilibrium, there is a fixed relationship between

allele & genotype frequencies: p2 + 2pq + q2 = 1

hardy-weinberg relationship equation

p2 + 2pq + q2 = 1

meiosis process (formation of gametes)

1 diploid cells containing pairs of chromsomes (aka 46 chromies in humans) > 4 haploid cells containing a single copy of each chromosome (23 in humans)

what’s crucial and random about meiosis and fertilization?

Thanks to genetic shuffling happening during sexual reproduction, parents with phenotype a can produce offspring with a new phenotype

what is different about meiosis in women>

formation of female gametes start in utero before birth, at birth 400k are arrested in prophase 1, at puberty meiosis resumes for 1 cell every 4 weeks and then stops at metaphase 2, then second division is only then completed if a sperm cells enters this gamete

can we predict someone’s height with their dna?

yes, 12.1k genetic variations are found to be assoc. with height however studies based on correlation between parent/offspring heights tells us that 80% of height variation is due to our genes. more research is needed

what is evolution?

a change in the frequency of a trait through time, can also refer to cultural, technological, etc

what are processes of evolution?

natural selection, mutation, genetic drift, and gene flow

what are some “rules” for evolution

evolution is not progressive (aka complexity does not necessarily increase), evolution can take diff paths, pace and direction and evolution can vary

what are the neutral evolutionary processes?

mutation, genetic drift, and gene flow?

what is mutation?

a change to the dna sequence, can be passed onto offspring if it occurs in a cell on the path to become a gamete, an uncommon but crucial process (it’s the only process that generates new alleles), usually harmful or neutral (neither harmful nor beneficial but sometimes can be beneficial) > reason for variation in genes

genetic drift

random chnages in allele frequencies in a population that is finite in size, genetic drift occurs when gametes happen to combine to form the zygote and some individuals happen to have more offspring than others by chance. happens faster in smaller populations than in larger populations,

what is the founder effect?

strong genetic drift when a group is founded from only a few ancestors

what is the difference between in group vs between group drift?

within a group: decreases variation, between group: increases difference

gene flow

increases within group variation and decrease between group differences

mutation-genetic drift balance

mutation and genetic drift balance each other, balance (equililibrum) is reached between amount of variation lost by genetic drift and amount of variation added by mutation, specific allelles will change but amount of variation will stay the same

what is the result of mutation + gene flow + genetic drift

tends to make nearby groups similiar

who is carl linnaeus?

published systema naturae (1735): HIERArchical classification of plants and animals, every species has a unique name combining two words (genus and species), called bionomial nomenclatture

modern taxonomy includes what?

domian, kingdom, phylum, class, order, family, genus, and species

who is georges cuvier(1769-1832)

studied animal/plant fossils, species appear and disappear (first to establish species extinction as a fact), talked about major extinctions following floods or earthquakes, didn’t think evolution was a gradual process

who was thomas malthus (economists, 1766-1834)

“ the struggle for existence”, wrote about competition and human population growth, humans tend to use availanle resources for growth than for improving standard of living, malthusian trap results the conflict between the interest if the individual and the interest of the group

who was jean-baptise lamarck (177-1829)

argued that species evolve (transformist theory, ridiculed by cuvier but mostly true), hypothesized that species transformation happens thru the use/disue of traits (which is not true), used traits inherted more than disused traits (also not true)

what are three conditions that are necessary for natural selection to occur

within population trait variability, link between trait value and individual reproductive success (ie number of offspring reaching reproductive age), trait value must be inherited

what dpes natural selection produce?

adaptations aka trait(physical structure or behavior) that is well suited to an organism’s circumstances (eg physical, enviroment, predators social group)

what is balancing selection?

natural selection maintains genetic variation by favoring multiple alleles at a locus (polymorphism)

what is stabilizing selection?

natural selection favors the trait average, maintaining the statis quo aka stasis

directional selection

natural selection favors individuals with traits that differ from the average, causing a shift in the average

what are some evolutionary constraints?

natural selection can only act on existing variation

what is reproductive success?

An individual’s number of offspring reaching

reproductive age is called the “reproductive success”,

or “fitness”. Humans reproduce more than one time

during their lifetime, so we often talk about “lifetime

reproductive success”.

what does reproductive success (fitness) depend on

whether a newborn survives until reproductive age

what is sexual selection

Sexual selection is the part of natural selection that focuses on

traits providing benefits in the context of breeding, Sexually-selected traits may be harmful to the individual’s survival

what are bateman’s principles?

which is the ecological sex?

females-their reproductive success limited by access to resources (food, shelter)

which is the mate getting sex?

males, reproductive success limited by access to females?

what is intersexual selection

favors traits that makes males more attractive to females

what is intrasexual selection?

favors traits that make males successful in competition with each other

what are females interested in when it comes to intersexual selection

Phenotypic” benefits – traits affecting female &

offspring survival directly aka resources and protective ability

• “Genotypic” benefits – males with “good” genes to

pass on to the female’s offspring

• Arbitrary traits – female preference can sometimes

develop by chance (outside the scope of ANT 1)

what are genotypic benefits?

some phenotypic traits indicate the overall genetic quality of male, color, age, body condition

intrasexual selection

favors traits that make males successful in competition with each other, largine canine teeth and large body size

kinds of intrasexual selection and competition

scramble competition-males increase their mating success by getting access to females first

contest competition: males increase their mating success by preventing other males from mating with females

what does scramble competition result in?

sperm competition (ie production and quality)

what does contest competition result in

evolution of traits enhancing fighting abilities (large body size, weapons, and aggression)

what does intense intrasexual selection

high sexual dimorphism?

what does pair living groups produce?

low sexual dimorphism, think of female and male gibbons?

what about altruism?

altruism: acts that are costly to self, beneficial to others

how do alarm calls create altruism?

+ reproductive success (RS) of listeners who are more

likely to escape the predator, but

• – RS of caller because it becomes more conspicuous to

the predator

what is the coefficient of relatedness?

is the proportion of alleles an individual shares with

another individual because they inherited it from the

same ancestor (e.g., r between full siblings is 1/2

what is hamilton’s rule?

altruistic acts will be favored by natural selection when:

benefits to recipient x coeffecient of relatedness > cost to actor

b x r > c

what is inclusive fitness?

a more sophisticated way of thinking about reproductive fitness

improved definition of natural selection

Natural selection favors traits that

maximize inclusive fitness

• An individuals’ genes are spread by

both direct and indirect fitness

basics of dna:

dna is a ladder-like molecule with a double stranded structure, has a backbone of sugars and phosphates, a pairing of special bases

what are the dna bases?

special bases are cytosine (c ), guanine ( g), adenine ( a), thymine (t). they match up so that c pairs with g and A pairs with T

what are genes?

series of base pairs, structural (instructions for making proteins) and regulatory (control when structural or other regulatory genes are switched on and off)

ways of measuring genetic variation at a molecular level?

blood groups (classical mark): individuals differ in protein found on the surface of red blood cells, differences determined by only a few genes, blood group is determined by mixing unknown blood with known type anti serum

what are different genetic regions

autosomes (22 pairs in humans), x chromsomes and y (xy male, xx-female) chromosomes, mitochondrial dna

mtDNA (mitochondrial dna)

Short DNA molecule found

outside the cell nucleus

Traces maternal lines of

descent because it is inherited

only from the mother

how can we quantify within species variation?

humans vs great apes human genetic variation>

in comparison with great apes, humans are genetically

homogeneous both in:

•Total variation

•Differentiation

Majority of human genetic variation is found within

major geographic regions

why are humans less genetically diverse than apes?

human population was much smaller fairly recently in the past (think founder effect)

what is race?

Many different definitions

• “Race” has been used to refer to

everything from skin color, to nationality,

to religion

• Confounds cultural, social, and biological

aspects of human variation

what do most people get wrong about race?

Human biological variation can be neatly

categorized into a small number of discrete &

permanent categories

Knowing a person’s race gives you representative

information about his/her genotype or ancestry

why do racial classification fail?

Most variation is found within groups

• Phenotypic variation can be due to

environmental rather than genetic factors

• Boundaries in human variation tend to be

smooth (clinal variation)

Different traits often result in different

classifications

what is unique about racial classifiations in brazil?

People are officially classified as “black”, ”brown”,

“white” by their “color” by the Brazilian Institute of

Geography and Statistics

Color” is assessed by skin color, hair type, eye shape,

…

Racial classification in Brazil

• “White” individuals are assumed to have Portuguese

ancestry

• “Black” individuals are assumed to have West African

ancestry

how does mendel’s discovery explain why racial classifications fail?

Genes for different traits are independently inherited =

independent assortment

• Genes for “color” are inherited independently from

other genes

• “Color” only gives information about genes influencing

skin color, etc., and not about any other genes a person

carries

how does the sun and melanin cause skin color variation?

UV radiation damagesDNA, causes skin cancer

• Destroys vitamin B9 (folate),which is important in preventing birth defects but Sunlight necessary to catalyze

the production of vitamin D Vitamin D necessary for

absorption of calcium Vitamin D deficiencies can

cause rickets

Melanin is a natural sunscreen

•Skin color reflects a balance between the harmful &

beneficial effects of sunlight at different latitudes

what is culture?

nformation that is:

• Capable of affecting behavior

• Acquired from others through teaching,

imitation, observation (social learning)

Type of information: knowledge, beliefs, values, skills

what is cultural evolution?

change through time in cultural variants

(information or its manifestations)