Anthro Term 1

What makes us human as primates

We don’t have tails which change locomotion

• Monkeys walk among branches

• Apes(hominids) swing below branches

Why don’t we have body hair

• Unusual among primates

• Thought to be associated with moving into the open/dry savannah environments

• Thermoregulation(evolution of sweating)

• Associated with evolution of dark skin pigmentation

Pediculus Humanus

Human head and body lice

• 3 main types; head, body, pubic(separate species)

• Human lice split from chimpanzee lice around 6 mil years ago

• Leaves the idea that body lice emerged after we invented clothing

Tools humans use: Fire

• How far back in the fossil record do we see evidence for fire?

• Fire for cooking(increases nutrients), warmth, deterring predators, managing landscapes, hunting, etc

• Burned animal bone

• heat treated stone tools

• hearths

Why do humans live everywhere?

Humans occupy an incredible range of environments

• rainforests, tundra, islands, deserts, savannah, high-altitude, woodlands

Most do not involve biological adaptions but cultural ones

• culture can evolve more rapidly than genetic adaptations

Facilitates rapid expansion into novel environments

• clothing, habitation, tools for plant use and processing, tools for hunting, knowledge of environment

Evolution

Change through time

• morphological change in the human body(ex: skull size)

Change in frequency of a trait over time

Traits

genotype or phenotype

Genotype

An organism’s unique set of genes, representing a specific genetic makeup (genetic code/DNA)

Phenotype

Set of observable traits (eye color, height, behavior) that is a result of genetic code (genotype) interacting with the environment

Evolution doesn’t only refer to genetic evolution

Morphological change of ipod to iphones

• Even when looking at our species we can talk about genetic evolution, cultural evolution, technological evolution, etc

Traits are;

An expression of an allele(alternate form of a gene)

What is evolution??

Evolution is the change in frequency of the alleles through time

Types of evolution

• Microevolution

• Macroevolution

Microevolution

The change in allele frequencies within a population over short time scales

(dogs/dog breeds)

Macroevolution

Large-scale/long-term evolutionary changes above the species level resulting in the formation of new species, genera, families, or higher taxonomic groups

• adding up microevolution events

Stasis Evolution Pace

• Stays the same, little to no morphological change

• living fossils (EX; Coelacanths)

• linked to punctuated equilibrium theory

Gradual Change Evolution Pace

• Evolving slowly and steadily throughout time

• EX: human brain slowly changing in the last 500,000 years

Punctuated Change Evolution Pace

• An explosion of evolutionary change after a stasis

• EX: human body changing about 1.8 mil years ago

Lots of Evolution adaptations

Evolution is not (linear) complexity does not necessarily increase

Divergent evolution

When related species from a common ancestor evolve different traits 9homogous structure) to adopt to different niches

• wolfs evolving also into foxes, coyotes, and different dog breeds

Convergent evolution

Unrelated species develop similar traits (analogous structures) due to similar environments

• Birds and bats

Mechanisms of evolution

• Mutation

• Gene flow

• Genetic drift

• Natural selection

Neutral evolution

Evolutionary forces that act with random chance on a population

• Mutation

• Genetic flow

• Genetic drift

Charles Darwin Works

Published his work when he was older but did his fieldwork in his 20s

Aristotle (Ideas before Darwin)

Notes an animal’s structure suited to its function

• linked the idea of structure and function of the body

Al-Jahiz (Ideas before Darwin)

• Wrote a book about animals

• Was close to proposing natural selection idea before Darwin

Jean-Baptiste Lamarck (Ideas before Darwin)

• Idea of organisms passing on physical traits to their offspring

• Lamarckian inheritance of Acquired Traits (Giraffe’s necks evolving to reach leaves on trees)

• Base idea of Darwin’s thinking with natural selection

Charles Lyell

• Geologist, Darwin’s bestie

Believed in uniformitarianism

• slow changes we can observe that accumulate over deep time, given that the Earth is old

Alfred Russel Wallace

• Independently though of the theory of natural selection from his fieldwork in the Amazon

• Worked with Darwin about natural selection later and published together since they both worked the idea independently

Darwin’s Theory of Adaption

• Voyaged on the HMA Beagle in his 20s for 5 years

• Was hired as a geologist then promoted to naturalist

• Produced a simple mechanistic explanation for how species change through time (Was drawing phenotypic trees in his notes)

Darwin’s Postulates

• Struggle for existence

• Variation in features

• Variation is passed from generation to generation

Make evolution by means of natural selection inevitable(ok Thanos)

Struggle for existence

1st Darwin’s postulate

• Hungry/fighting to survive

• Limiting resources/ predation/ finding mates

Variation in features

2nd Darwin’s postulate

• Coat color/ teeth/ patterns

• Adaptations

Variation is passed from generation to generation

3rd Darwin’s postulate

• Adding up to evolution

Did Darwin’s postulates work?

Biologists Peter and Rosemary Grant collected finches to study to make sure Darwin’s postulates worked

-was in Galapagos Islands, Ecuador

Darwin’s Finches

• Drought hit and population went from 1200 to 180 (1st postulate)

• These finches had variation in beaks, short vs. longer/deeper beak. Deeper beaks can break the seeds easier, more access to food, Beak depth varied; affected survival (2nd postulate)

• Beck depth passed from parent to offspring (3rd postulate)

Selection does NOT have an end goal

Types of Selection

• Disruptive selection

• Stabilizing selection

• Directional Selection

Disruptive selection

Variation spread out, environ is targeting (selected against) a certain phenotype variations

Climate change can disrupt the selection pressures on populations

Causing the population to split into distinct groups, increasing genetic diversity, and potentially leading to new species

• EX: a tri-colored population can show selection pressure that favor only 2 phenotypes (rabbit example)

Stabilizing Selection

• Will maintain status quo as long as the environment is constant

The average trait is favored, while extreme variations (both high and low) are selected against, leading to reduced genetic diversity and a population that stabilizes around the average trait

EX: Darwin’s Finches

Directional selection

• Where one phenotype(trait) is favored, causing the population’s average trait to shift in that trait over generations

Driven by environmental changes or pressures favoring certain adaptations for better survival or reproduction

EX: Peppered moths

Artificial selection (Domestication)

Humans have domesticated and selectively bred plants and animals

• Rapid changes have been achieved in few generations

EX: Dog breeds

Se*ual Selection (Have to misspell it due to restrictions)

Not really mentioned with traditional mechanisms but plays a BIG part in evolution

• Stronger and faster than natural selection

Se*ual dimorphism

• Trait changes in one se* of an animal

• Size + dichromatism(changes in skin/fur/scale color)

How id Se*ual Selection different than NS?

Selects for traits that increase the relative fitness of an individual by allowing them to secure greater mating success

• Se*ual selection can work in opposition to Natural selection by selecting for traits that compromise survival

Intrase*ual Selection

Intra= within(se*es)

• Male to male competition

• Dominant males gain access to females

• Males are bigger than females

Interse*ual Selection

Inter= between(se*es)

• Females choice

• Females selects most attractive male(boys are prettier lol)

• Females are bigger than males

Mating systems

• Monogamy

• Polygamy

• Polygyny

• Polyandry

• Promiscuity

Monogamy

Individuals mate exclusively with each other

keep in mind that extra-pair copulations, EPCs do occur frequently

• Sequential monogamy is the type of monogamy seen in primates

Polygamy

Individuals mate with more than one partner

Polygyny

Males mating with more than one female

Polyandry

Females mate with more than one male

Promiscuity

Individuals mate indiscriminately with multiple partners

Pair bonds w/se*ual dimorphism

Have little male-male competition: little dimorphism

One-male, multi-female w/se*ual dimorphism

• polygyny

Huge body and canine dimorphism

Multi-male, multi-female w/se*ual dimorphism

• polygamy of promiscuity

Large dimorphism

Intrase*ual: Multi-male/multi-female

Sperm Competition

• Males with larger sperm volume have greater chance of fathering offspring

• Evolution selects for t*stes size

• There is evolutionary trade-off between t*stes size and hyoid bones in howler monkeys (louder they yell=more likely of finding mates)

Interse*ual: Female preference

• Colorful traits

Mandrills (EX: Rhesus Macaque (Rafiki) gets more red in the face during mating season)

• Grooming

• Access to Resources

• Protection (for them and their babies)

Se*ual Selection in Humans

Low se*ual dimorphism

Possible se*ually selected traits:

• lack of baculum(pen*s bone)

• Permanent br*asts in females

Mate culture can be affected by culture

Constraints on Natural Selection

Natural selection can only act on variation in the population

• new variation comes from mutation which is random chance

May be a slow process and takes lots of steps to get to a phenotype that is adaptive

• EX: whales from land animals (convujent evolution)

• Can see slow changes add up to modern phenotype traits through fossil records

Global optimum

Natural selection is “blind” so a population doesn’t always reach the best solution

Local optimum

Sometimes a population gets stuck at just a good solution and does not reach the best solution

The dynamics of the developmental mechanisms serve to constrain which phenotypes are biologically realizable

• Developmental constraints

• Mechanical constraints

Developmental constraints

The heart

• different sizes for different species (EX: Humans vs. fish)

Mechanical constraints

All mammals have 7 vertebrae

(Giraffe’s vertebrae are much bigger(like a foot) compared to humans)

If the number of vertebrae changes it would change the developmental forces to help support neck/life

Some traits are correlated to others;

this can occur phenotypically (length and width) or genetically (location on the allele)

EX: beak depth and width are correlated in Darwin’s finches

Some natural populations may now be imperfectly adapted because accidents of history pointed their ancestors in what would later become the wrong direction

EX: Giant pandas- vegetarians with false thumbs

Due to moving to a vegetarian lifestyle from meat, their gut had to evolve and evolved a false thumb to help hold and eat the bamboo better

Genetic constraints on adaption occur when the heterozygote at a locus has a higher fitness than either homozygote

EX: Sickle cell

No protection from malaria for normal (AA) where they don’t have it

But Aa and aa gets protection/less sick from malaria due to proteins not forming/destroying blood cells in malaria

Neutral forces of evolution can influence an evolutionary path, constraining natural selection

Bottleneck and Founder’s effect

Genetic drift constrains adaptations

How have humans affected the evolution of ourselves/other species?

• Over exploitation of resources

• Habitat destruction

• Invasive species

• Pollution and rapid environmental change

• Artificial selection

• Cultural and technological buffering

DNA

Discrete unit of inheritance which contains the recipe for creating cells and differentiating those cells into a whole organism

• 4 nucleotide bases; Adenine, Guanine, Cytosine, Thymine

• Nucleotides are paired in a double stranded matter (double helix)

• very stable formation, degrades less quickly

Chromosomes

Humans have 22 autosomal chromosomes plus the sex chromosome (23 pairs of chromosome in total)

Amount of chromosomes are different for every species

Mitochondrial DNA

Available in every cell

• a short chromosome

• maternally inherited

• multiple copies

Diploid

Humans have diploid autosomes (2 copies)

• Females are diploid for XX

• Males are haploid for XY

They receive 1 copy of each chromosome from each parent (called a gamete) and are 50% identical to either parent (except for mutation)

Somatic cells (clones)

are diploid

S*x cells/Gametes

All 4 cells are different

Haploid

2 ways Meiosis creates new genetic variation

1. 50% chance that a parent will pass on either chromosome of a given homologous pair

2. Genetic recombination ensures that even offspring with the same parental chromosomes will have different genetic makeups

Mutations and DNA replication

• Replication is when most mutations are introduced

DNA must unravel to allow cellular mechanisms to attach

SNPs

Single nucleotide polymorphisms

• most are neutral

• few are deleterious or beneficial

Synonymous mutations

Code for the same protein

Nonsynonymous mutations

Code for different protein

Natural selection can act on this

Gregor Mendel

Discovered laws of inheritance

Bred garden pea plants (1856-1863)

Worked with traits of two variants

• Color: yellow or green

• Texture: wrinkled or smooth

Mendel’s Crossbreeding Experiment

• F generations

• Genes inherited; 1 from the mother, 1 from the father

• Independent assortment

These are discrete traits, not continuous

Law of Segregation

Characteristics of organisms are determined jointly by two “particles”(alleles), one inherited from each parent

-offspring get one allele from each parent

Law of Independent Assortment

Alleles for different traits are inherited independently of one another

Genes do not influence each other with regard to the sorting of the alleles into gametes

Law of Dominance and Uniformity

Some alleles are dominant over other particles (for example yellow is dominant over green in Mendel’s pea experiment)

Hardy-Weinberg Principle

States that allele and genotype frequencies in a population remain constant from generation to generation in the absence of evolutionary influences

-Genotype frequencies in the Hardy-Weinberg principle are inherited by maintaining constant frequencies across generations due to random mating, no selection, and no mutation or migration.

Hardy Weinberg Equilibrium

• Population is infinitely large

• No mutation

• No genetic drift

• No gene flow

• Natural selection is not operating

• Mating is random

• All members produce same number of offspring

Hardy Weinberg Equation

Predicts genotype frequencies for the next generation after one mating

Determines if evolutionary change is taking place or if the population is in equilibrium

• If it is not in equilibrium, the population is still evolving

Non-Mendelian Inheritance

• Polygenic traits

• Pleiotropic traits

• Incomplete dominance

• Codominance

Polygenic traits

Involves multiple genes influencing one trait (height/skin color) leading to continuous variation

Pleiotropic traits

Occurs when a single gene affects multiple, seemingly unrelated traits

Incomplete dominance

Where traits blend (pink flowers from red & white)

Codominance

Where both traits appear (AB blood type)

Environment Inheritance (Non-Mendel)

• Phenotypic plasticity

• Heritability

Phenotypic plasticity

The ability of a single genotype (organism) to produce different, observable, or measurable trait (morphology, physiology, or behavior) in response to varying environmental conditions

• The property of organisms to produce distinct phenotypes in response to environmental variation

Heritability

Trait is how much is genetic and how much is something else (environment)

Mutation

Change in an organism's DNA sequence, caused by replication errors or environmental factors, which can be harmful, beneficial, or neutral, and can be passed to offspring if it occurs in reproductive cells (gametes)

• A spontaneous change in the chemical structure of DNA

Beneficial Mutation

Lactase persistence

• Stop production of lactase enzyme between ages 2 -12

• A genetic trait allowing adults to digest lactose, the sugar in milk, due to the continued production of the enzyme lactase

Harmful Mutation

Cystic Fibrosis

• F508 mutation

• Deletes 3 DNA bases

• Seen in populations all over the world

• Smaller populations are more affected (genetic drift)

• Recessive gene = parents are heterozygous carriers