Human Origins UNIT 2 JHU

pls help.

viviparity

giving birth to live young

diurnal

active during daylight hours

conspecifics

members of the same species

sexual dimorphism

Differences in physical characteristics between males and females of the same species such as body size

What defines a primate?

--Five digit grasping hands and feet

--Nails instead of claws

--locomotion is hind limb dominated

--olfactory apparatus is decreased in day active primates

--vision is developed

--Relatively large brain

--Slow "life history"

--molars are unspecialized

brachiation

a method of movement that uses the arms to swing from branch to branch

binocular vision

2 eyes overlap so you can get the same image

stereoscopic vision

each eye sends signal to either hemisphere to create image depth

stepsirrhini ( breaks into..)

a semi order- then stepsirrhini sub order- then- leumuriformes (lemurs) and lorisiformes (lorisi)

Stepirrihini describe

nocturnal- they have the tapetum lucidum that helps them see at night,

they have enhanced olfaction, but a relatively small brain,

and tooth combes,

arboreal quadrupeds and female dominated

( wet nose primates)

lorisiformes

Found in Africa and Asia

• nocturnal

• -arboreal

• -enhanced olfaction

• -infants nest while mothers forage

• eat insects fruit and gum

Lemuroidea

Madagascar/ COmoro Islands

-nocturnal

-olfaction

-dental comb

-arboreal quadrupeds

-female dominance

-lemurs evolved in sisolation because of pangea

Haplorrihini Breakdown

into anthropoedia and Tarsiformes (tarsiers)

then Anthropoedia goes into Platyrrhini (new world ) and Catarrihini (old world)

then Catarrihini goes into Cercopithicoidea and homonidea

Homonidae goes into ponginae ( orangutan) and hominia (goriallas, chims, bonobos, and humans)

Cercopithicoidea goes into cercopithicae (baboons, macaques, and vervets) and colobinae

Tarsiformes

Tarsiers 

-nocturnal

• faunivores ( insects)

• grooming claw

• pair bonded families 

• give birth and leave child in nest

• ONLY insects

Platyrrhini

• flat noses

• arboreal

• prehensile tail

• New World Monkeys (Central america and Mexico)

• diurnal

(howler monkeys and spider monkeys)

Catarrihini

• old world monkeys

• monkeys, apes, humans

• larger than platyrrhini

Cercopithicinae

• after catarrhini

• Asia and Northern Africa

• cheek pouches

• ominorous

• arboreal

• strong female bonds

• dominance hierarchies

• leaf monkeys (colobinae)

ie. macaques

Homonidea

After catarrihini too

• Lesser apes, apes, and humans, and monkeys

Homonidea

• humans and great apes

• Ponginae (orangutan- solitary and eat fruit, use tools)

• Hominae (gorillas chims banobos and humans)

  • Gorilla (largest, polygyny, moutain is leaf and lowland is fruit)

  • Chimpanzees ( Pantroglodyte- tool use and male coalition) (chimps and bonobos are polygynandrous) 

  • Bonobos( Panpaniscus- female bonding, peaceful)

  • Humans ( Flexible social structure and culture/ language)

Large brains lead to

increased intelligence characteristics

ie. dolphins

Dentition

• can tell us about age ( wear)

• can help us with phylogenetic relationships

dental formula

2.1.3.3/1.1.33

• top is inciscors, canines, premolars, and then molars ( maxilla)

• bottom is the same but called mandible

gum diet

• large inciscor 

• canine projected forward

• long cecum

Insects/leaves diet

• molars are well developed to chew

• pointed cusps on molars to pierce body

• short and simple guts

• leaf eaters have  enlarged LI and different thingies for cellulos

Frugivore

• flatter cusps to crush fruit

• long small intestine

• large stomachs sometimes to hold more contents of leaves with fruits

hard seeds/ nuts

molars with thick enamel

prehensile

• grasping tails 

Amount of energy used is affected by..

1. basal metabolic rate ( increased body size increased metabolism)

2. Active metabolism ( additional calories needed when active)

3. Growth Rate ( need more energy to grow)

4. Reproductive effort

secondary compounds

toxins to protect yourself from eating

ie. alkaloids which go from stomach directly to cells

carbohydrates

simple sugars in fruits

fats

animal prey

protein

insects/leaves

vitamins/fats/oils

seeds

Size of the Eaters

Insectivores< frugivores< folivores

bigger animals need more quantity than quality

Where do primates live or stay arounnd

their home range and trees

small arboreal monkeys face less risk

ie. gibbons stick to their territories

What are common responses to predators

fleeing and alarm calls

Sociality ( benefits)

Most primate groups stay in groups due to predation

the individual is less likely to be hunted

larger groups can exclude smaller groups from resources

Costs for sociality

more competition for resources in the group→ dominance hierarchies

more time feeding ( having to wait for friends)

more infections

When is an outcome of a fight predictable

if there is stable differences in size/power of opponents

Solitary

males usually are individuals but can overlap w female territories

Polygyny

one male and many females

Pairs

two couples together

polygynandry

alll together (hoes)

Female reproductive success

female RS depends on females themselves- their age, experiences, or resources

strategy

a set of traits used to solve a rpoblem such as finding food

Mating effort

• locating mates and gaining access to them

ie. courtship displays or competition

parenting effort

• activities related to caring for offspring

Males vs. Females on ME and PE

• females invest in PE and males in ME

  • males do not care as much about offspring vitality but female fitness is based on quantity of offspring

Developmental constraint ( ex)

• if males can lay eggs, that could leave them sterile

Females bodies and effort due to pregnancy

• The larger the animal the bigger the pregnancy and lactation

• due to this effort, primates have smaller litters

• females reproduce throughout their lives

Females need..

food to reach maturation

the more food the more babies and the earlier the maturation

interbirth

interval between births

dominance ranks created by..

dominance ranks are created by competition of food

the higher the ranking the more access to resources

cooperative breeding

• everyone helps to take care of the babies, but only one female breeds (dom female)

How does being social help with RS?

• more social people can have better protection from predators or getting food

• you live longer and have less stress when it gets to it

What does sexual selection lead to?

• it leads to more competitive males

• it can also lead to outcomes that are not favored by natural selection

Intersexual selection

• makes males more attractive since they are fighting for female attention 

ie. the peacocks

““

intrasexual selection

• competition among the same sex

• leads to sexual dimorphism

  • such as for mates or for land

ie. this can leads to larger bodies and more aggression in children 

Strength of selection varies with..

• variation, which affects males more strongly

ie. males have a higher potential for variation because they are not limited by biological constraints such as gestation or bodies

If more females than men..

• there is increased competition between males to monopolize them

• this is polygynous groups where a lot of women one man

Sperm Competition when

• in polyandrous groups

this is not important in polygynous or pair bonding because males dont really compete to have sex with women they know who theyre with

estrus

portion of time where females can reproduce

pair bonding (parental investment)

• associated with more parental investment because males are sure those are their children

cooperative bonding

• infants can be sired by different males but there is only one breeding female

• males help with children which increases fertility in women

Polygyny ( PI)

• male RS depends on if they can stay in their social group since they need access to females

• other men can come in to have sex with the girls, and with more females there are more takeovers

• followers can be let in to help protect the females and increase the percentage of kids that the dominant man is going to have

• might let followers sire if they can stay on throne

Males in Polygyny

• males usually invest more time in mating effort

• EXCEPT gorillas - they take care of the babies even if they are not theirs

Polygynandry

• males compete to get access to females that are sexually receptive

• and very successful males sire a large amount of the children

• large reproductive skew

ie. muriquis are an exception because not as much difference

• males sometimes interact with offspring if it is theirs

Sexual Selection Infanticide Hypothesis

• sexually selected males will kill the children of females if it is not theirs so that females will go back into estrus and can have their babies

Counteractions to sexual selection infanticide hypothesis

• females will make friends w males that will protect them

• have sex with too many men to confuse paternity

• abort the child

Altruism

• beneficial to others but costly to yourself 

ie. grooming and alarm calls

Are warning calls a method of NS?

• no, warning calls are only a method of group selection if there is there is increased genetic variation in a group

• however, individuals have more variation which makes individuals the increased force for selection

mutualism

• a cooperative action that helps both people

ie. a coalition where two more sub men work to guard a female

kin selection

• natural selection will favor altruism if they are kin due to the passing on of your own genes

ie. warning calls for siblings

however, if you guys are siblings they is a large chance that they are also alarm callers, increasing the amount of alarm callers in a group which shows how that trait developed

Hamiltons Rule

• rb>C

altruistic behaviors are more favored when the the relatedness of siblings times the benefit is higher than the cost of the behavior

• altruism is limited to kin and the more kin the more costly it is considering you are going to be more altruistic

Kin Recognition

• this can be done by phenotypic matching where you can recognize kin by how much they look like you

• it can also be seen by how familiar and proximal they are to you

• there are contextual cues to meet kin, which is seen by residence or time of conception or even similarity in age

  • paternal siblings can be harder to fin but are seen by age

Kin Biases

• biases include social grooming, where the participant gets cleaned and the doer gets a social relationship

  • cost- exposure to pathogens and excessive time spent doing that

• more w kin than not

• coalitions- grouping together for attacks and support happen more w kin

important in macaques, vervets, and baboons.

• maternal support usually leads to daughters winning and their rank is near their daughters

ie. red howler monkeys form coalitions

matrilineage

• rank of maternal kin group

• daughters and mothers are close since moms help daughters fight

• mothers<older<younger

Kin Selection in cooperative breeding

• all members care for offspring

• males in these situations are more likely to be related because they live together and have kids

Kinship reduces—-

• competition in females since dominant females are more likely to share men with their sisters/ offspring

Parent-Offspring Conflict

• infants will get mad when parents leave them for other infants

• kin selection explains this conflict because mothers are equally related to all infants, but infants are more related to themselves

• mother will take care of the present child until cost of future child is less than benefits of present

Reciprocal Altruism

• altruism is going to evolve if others are likely to help them back in the future

ie. grooming someone because they are likely to groom you

ie. protecting someone because they are willing to fight for you in the future

BUT there are 3 rules

1) the individuals have to interact often

2) they have to keep track of who helps them and who dont

3) they have to provide support to only those who help them

male relationships are based on-

• kinship, not reciprosity

What advantages does having a large brain include?

• overcome social/ ecological challenges

Social Brain Hypothesis

• selection favors larger brains because primates have to deal with high social challenges.

• hypothesizes that brains are going to be correlated with size of groups/ coalitions or the capacity to socially manipulate

Ecological Brain Hypothesis

• ecological challenges lead to larger brains in primates because primates have to use their brains to forage/ find food

• spatial knowledge and challenges while foraging

dyads 

• pairs

Third party relationships

• relationships among other individuals not including yourself

Redirected aggression

• attacking kin of the original attacker

ie. if man attack u, u kill man sister

DO monkeys know about others socially?

yes monkeys know about other monkeys dominance ranks and who they relate with most often

Theory of Mind

• Primates are aware of the mental state of other monkeys

  • ie. chims are more likely to give alarm calls to monkeys they know do not know the predator than monkeys they know that do.

False beliefs- Do primates understand them?

• False beliefs are things that people think are true but are not ( ie. flat earthers)

• Primates understand this 

  • ie. Dr. Krupenye study where man in monkey suit hides in little hut when human is watching and then switches when human is not

  • primates understand that the human wil expect him in the place where they saw him go.

Life History theory

• This theory is about allocating energy and describes how primates have a “slow” life history

• Allocating energy to reproduction means that that there is less for growth and maintenance

Senescence

aging

Why are primate lives not longer if NS acts?

• There is a tradeoff between reproduction and living.

• Characteristics that prolong life are not going to be favored if they mean less reproduction

• aging is selected because traits that increase young reproduction/ fertility are picked.

  • also traits that occur after reproducing are not selected against 

Traits of early reproduction

• smaler body, smaller gestation, increased litter, and increased mortality

ie. think of a fly

also smaller bodies take less to be developed so more of them and younger

elephants take forever

Large animal characteristics (repreoduction)

• large animals have longer juvenile periods that lead to more complex brains

  • they reproduce over linger periods of time

Short/ long continuum

Primates have longer/ slower life history

Ranking Life History

Monkeys have lower life history than stepsirrhines and great apes have slower life history than monkeys

If fast life history?

• monkeys will have faster reproductive system.

If large animals get enough resources?

• They will have longer lives and wait for maturation.

• they need more food/ resources, but if they do then they will wait.

• they optimize lifetime reproductive success