The Evolution of human sex roles and reproduction

Ethnography is

participating in everyday life with your subject

Anthropology

The study of humankind in all places during all humankind.

4 branches of evolution

Mutation, Gene Drift, Gene Flow and Natural selection

Mutation

Introduction of new genes by chance which are transferred to offspring> This is also when DNA is restructured

Gene flow

When an organism moved to a different population genes are then transferred.

Gene drift

When a gene becomes dominant when the majority of a small population dies (bottleneck example)

Species

A group of organisms that breed

Great chain of being

Species are organized from lowest to highest. It’s in their innate tendency to be moving up in the hierarchy.

Giraffe

They didn’t have long necks because they extended them to reach higher plants. Giraffes who had genes (characteristics) with longer necks could survive longer (Natural selection)

Why doesn’t our populations increase out of control?

Due to limited resources like food water and safe environments our populations are kept in check.

Natural selection

The struggle for existence which depends on biology. (genes) Genes are “filtered out” to fit their environment This process over time leads to evolution

What did the Moths in England prove?

You can see evolution & it can be human made

What does the mutability of species mean?

It means species have the ability to change over time. Species weren’t created by God in a series.

What made people like Lyell believe the earth was actually older than 6,000 years old?

Land masses like Volcanos, canyons and rivers concluded these processes took longer than 6,000 years.

What does common decent/Branding Evolution mean?

All life had a common origin before it branched out into species.

Antibiotic resistance

* Few of our bacteria have abilities to survive antibiotics.
* They can pass those characteristics onto their offspring.
* This is why you must use a different antibiotic each time. So those bacteria don’t have preferred conditions to multiply.
* They can even transfer their characteristics to other bacteria which can cause problems.

Reproductive sucsess

This is a main point in Natural selection. You can live without having offspring but in Natural selection there won’t be as many people in the world with your genes compared to if you have offspring.

Differential Reproductive Success

The reproductive success of different traits (Must be genetically determined & different)

Domesticated Plants/Animals

We have bread animals to create traits that benefit us

Geographical Distribution of plants & animals

Fish have breathing abilities, species in colder climates tend to be bigger.

Comparative anatomy

Our similar limbs told Darwin that these animals shared a common ancestor.

Embryology

We seem to go through the same developmental stages (birthing, embryo, fetus) before our differences are showcased

Vestigial organs-

We have organs left over from our ancestors

Evolution vs Deveopment

Evolution is what happens to a species over time. Development is what happens to an individual over time

Sexual Selection

Male-male competition- males compete with each other for the opportunity to mate (deer’s have rituals or battles)



Females are choosing which male to mate with based on attractive characteristics. (May choose a peacock who has the most feathers)

Why don’t women have as many children as they can?

Resources are limited, you wouldn’t be able pay for all of them (Limited resources keep us in check)

Lack Effect

What’s most successful (reproductively) is the one that’s most common. Selection has acted against laying too few or too many eggs. The maximum isn’t necessary the optimum.

Bad Year

Resources are scare. You’re better off having the optimal amount of offspring

Good Year

more resources means you can make more offspring therefore having more reproductive success.

Differences between males and females in reproductive success

For males the more mates they have the more offspring they have.

For Females adding more mates doesn’t improve their reproductive success. There is a limit is because of her body: 9 month pregnancy

Variation & Reproductive success

Males have much higher variation reproductive success even though the average of the number of offspring is the same. Females have lower because of their bodily limits.

Risky behavior

Behaviors that can lead to an individual’s demise. (Male vs Male competition- Sexual Selection

Why doesn’t Natural selection interfere with male vs male competition if it’s a risky behavior?

It doesn’t interfere because these males will have more mates and become reproductively successful.

Why do males die more frequently than females?

Males participate in Risky behavior such as Male vs Male competition that put them in danger. In the sense of duties, they can typically be more dangerous than female duties. (Hunting, soldiers, etc)

Polygyny threshold

A reason why you might get another mating system

o   Females chose mates on the bases of the men’s “best territory” depending on what gives her the best reproductive success. So instead of taking of the territory of the 2^nd best they choose to be the 2^nd partner of the bird who owns the best territory. Or the 3^rd partner

-Are animals considered human? Do they have culture

o   Chimpanzees use tools. The chimpanzees fished for the termites with a stick.

o   They groom each other – this is mostly a social feature

Why does it take monkey’s longer to learn things

Unlike us, we have language so communication is easier and faster

Social Insects

there is one individual that reproduces at a time and the members of the colony helps the individual reproduce. (Queen bee and worker ant) These worker ants don’t have reproductive success but help the queen bee who is a close relative. They are clones of the queen. So in turn they are spreading their genes.

Eusocial

o   one individual reproduces and the members help the individual reproduce

Territorial aggression-

o   the more related they are the less they’re likely to be chasing out of territory

Sociobiology

study of behavior of evolutionary perspective  

Reproductive success and Rank

The top ranked is mating more often than lower ranked. Having a high rank may have some reproductive success.

Ovulation

 (during a woman’s ovulation the probability of mating increases)

Privative features-

From our ancestors

Derived features

Features that evolved recently

Primate Characteristics

-        Live in tropical regions today

-        Eyes are forward on our head

-        Fingers ending with nails nut not claws, with padded fingertips s

-        Separate radius and ulna

-        Stereoscopic vision & development of the brain related to vision

-        Small or moderate face

-        Multiple forms of locomotion. (walk, leap, climb)

Encephalization Quotient

-        Way to understand how big your brain is relative to your body. 

-        When you look at primates they are all above the line that defines a brain being bigger for their body size.

Mechanisms

Ways evolution happens

What do Humans have but other species do not?

-        Large brain

-        (Bipedalism)- How we walk on two legs

Things we share with some other people (We share the same culture)

-        The way we raise our children.

-        Clothing

-        Food

-        Language

Things we share with no one else?

-        Morals and values

-        What you like, preferences, personalities etc

Who are we closely related to?

to chimpanzees,(Sister) Gorillas,(1^st cousin)  and Orangutans (2^nd cousin)

We are share the same relations between us and a chimpanzee as a gorilla has with a chimpanzees.

True

Sexual dimorphism

Differences on average between male and females that concern secondary characteristics (body size, fat levels, shoulder length) They don’t relate the reproduction

There is a huge overlap in the average in height for males and females. There are some males who are shorter than the average female visa versa.

Life History Theory

Organisms differ in how they develop, the time they take to grow, when they become mature, how many offspring they have at a time, what the fertility and mortality rates are. It tries to explain how natural selection shapes reproductive success and maximizes it.

R selection

Many babies but not investing much in each one, higher mortality rates (Fish, Insects)

K selection

less babies investing more time, lower mortality rates (Humans, Birds, Monkeys & Apes)

Tradeoffs

disadvantages or advantages to reproductive success.

When an animal has bigger body mass it takes longer for gestation.

True

If it’s more beneficial to have children earlier why don’t human do that?

Culture is the way we make our way in the world. Not instinct. We learn those behaviors that takes a lot of time

Growth

increase in size or mass

Development

changes of state. They go from immature to highly organized, speciated and mature state

Maturity

functional capacity- reach the ability to function as an adult

Birth

critical transition between life in utero and life outside the womb

Longitudinal study

Doesn’t decrease only increases, even if it’s slowly. Measure over their lifetime every perhaps 6 months. A harder way to get info.

Cross-sectional

taking a cross section of a population. You’d be using children of different ages and have your graph that way. Easier way to get information. However, if something like a famine happens the data will be impacted.

monogamous

having one partner

polygynous

having several partners

Why isn’t evolution about the origin of life?

Evolution is a biochemical event. It isn’t explianed by evolution.

Why doesn’t evolution result in progress? (great chain of being)

Due to the fact that circumstances change. Big, faster animals aren’t always better for reproductive success.

Do individuals or species change in evolution?

Species

Why isn’t it always true that evolution happens slowly?

The Extinction of the dinosaurs happened very quicky..

Can humans influence evolution

Yes they can, Sickle cell anemia was a direct response to Malaria. (People with sickle cell anemia are “resistant” to Malaria. Humans also have controlled breeding like birth control which effect the population size.

Does genetic drift only happen in small populations?

Genetic drift doesn’t just happen in small populations. It’s just more unlikely to happen in bigger populations.

Are humans still evolving?

Yes, if there wasn’t any evolution, we would be having the same number of offspring, there would be no mutations. There would also be no genetic drift or gene flow.

Does natural selection give species what they need?

No, just because something may be easier doesn’t mean natural selection acts upon it.

Can humans negatively impact ecosystems even though specices will just evolve what they need to survive?

Yes because very rapid environmental changes wouldn’t give species enough time to adapt.

Natrual selection acts for the good of the species

It acts on reproductive success not for the betterment of the species

Are all traits of organism adaptive?

No, for example the bridge of our noses that hold up glasses weren’t formed to hold up glasses.

If differences between males and females are evolutionary or hardwired what would we need to support this theory?

The differences would need to be biological not cultural.

Catch-up growth-

A period of malnutrition and then it’s alleviated.

Why should be critical of graphs?

Take graphs with a grain of salt because data is normally taken from white, middle class populations. Not populations who may be malnourished.

What is one of the parts of the human body that grows the fastest after birth?

The brain tissue (Normally fully grows by 5)

What are some Physical developmental millstones of childhood?

Dental eruption

Completion of brain growth

Other correlates of maturation (Individuals who mature more fast will have other systems grow faster as well same as ones who grow slower

Why is there a significant decrease in the starting age of menarche across the world?

What accounts for this is better nutrition

It’s an environmental cause that impacts this. (Body fat, Nutrition)

Secular trend

a change from one generation to another that’s not evolutionary (not a change with genes)

How does life history impact how mnay children are born?

Cultural practices (How long do they nurse, do they use birth control etc)

Asexual Reproduction

Characteristics are cloned. Better in an unchanging environment The environment won’t need someone to adapt.

Sexual Reproduction

mixture of characteristics

If circumstances change and that type of offspring don’t adapt well then evolution becomes harder.

Is Kissing universal for humans? , Is it natural? (In our genes, something we share with other animals)

We don’t know If the behaviors that look like kissing are actually how we perceive kissing in our culture. Just because something looks like a behavior, we do doesn’t mean it is that behavior.

Why can’t we use hunter gatherers as model of hunter gathers in the past?

They are modern humans.

Different from past hunter gathers.