Evolution yr2 sem1

what are analogies

traits that have evolved independently in different species but look the same - for example birds and bats have both evolved wings

convergent evolution

the type of evolution that produces analogies - two species evolving separately to have the same/similar trait

what are homologies

traits that are similar by evolutionary descent - they can look very different

i.e. humans, cats and whales have the same body plan for arms but they all look completely different

what is adaptive radiation

when an ancestral species rapidly diversifies into new species - occupying different ecological niches

how can we tell which traits are homologies and which are analogies

the comparative method

checks their phylogenetic history and ecological pressures

what is a vestigial trait

traits that have lost their function through evolution

used to be useful and adaptive, not aren’t useful i.e. tail bones

what are behavioural vestigial characteristics

behaviours that used to be adaptive but are less so now

i.e. phobias - we have fears of snakes eventhough we have likely never come across a poisonous one before

explain ‘just so stories’ - Kipling

not plausible origin stories

stories made for children explaining where they got their traits from

i.e. elephants got their trunks because crocodiles pulled their noses

exaptations

traits that evolved to solve one problem, but then play a new adaptive role i.e. feathers evolving for warmth but now being adaptive for flight

explain how traits can be a developmental byproduct

traits can arise as a byproduct of another trait being selected for

i.e. men have nipples because women have nipples and there is no pressure/reason for them to get rid of theirs

explain how traits can be maladaptive

they used to be adaptive, but are now harmful

i.e. our preference for sugary and fatty foods used to be adaptive when it was scarce, but now it is abundant it is making us obese

explain what phylogenetic inertia is

limits on what can evolve due to previous adaptations

i.e. flying pigs

not all traits can evolve because of physical constraints and our evolutionary history

what is Orgel’s second rule

Evolution is more clever than us as it can come up with unusual solutions to problems

i.e. platypus’ having a beak that can detect electrical signals in the water to locate prey

what does it mean for evolution to be ‘for the good of the species’

natural selection doesn’t favour species who kill themselves ‘for the good of the group’

it takes a gene’s eye view - killing yourself to relieve pressure for the rest of the group you don’t pass on your genes

explain the is-ought fallacy aka Hume’s Law

just because something did evolve, doesn’t mean we ought to act that way i.e. just because men evolved to be more aggressive than women doesn’t mean they ought to be

explain the naturalistic fallacy

just because something feels good doesn’t mean it is

‘goodness (morality) cannot be reduced to natural properties’

explain biological determinism

there is no biological determinism - our genes and evolution do not determine our fate

i.e. just because men are evolved to be more aggressive doesn’t mean they WILL be

explain the nature vs nurture debate

genes vs environment

they both influence traits so the argument is a false dichotomy and too reductionist

what is social spencerism

discusses societal evolution

economies and societies follow the same principles of natural selection - like survival of the fittest

name one way darwin’s idea has been misused

eugenics i.e. nazis

what is the EEA

Environment of evolutionary adaptedness

the EEA is the environment we have evolved in - specifically the african savanna (as we did 99% of our evolution here)

who coined the term EEA

Bowlby

What is adaptive lag

when adaptions can’t keep up with the changing environment - leading to traits that used to be adaptive, but now aren’t i.e. phobias

what are 4 core principles of evolution by natural selection

1. heritability

2. variability

3. surplus offspring

4. nonrandom survival and reproduction

give examples of evolution not due to natural selection

mutations

genetic drift

founder effect

mutual selection

criticisms of evolutionary psychology:

not very different from sociobiology

out of date understanding of evolution

give some key features of the behavioural ecology approach

ecology - how the immediate environment impacts us

optimality - the best possible solution given the environment

not interested in cognition

what is the goal of the behavioural ecology approach

to determine how differences between individuals can be explained due to optimality and fitness explanations

who studies the !Kung

DeVore

!kung is a tribe in tanzania who DeVore studied to see how ecology impacted their behaviour

how does the behavioural ecology approach use historical data

looks at birth records and birth rates

links with environmental information i.e. wars at the time to see how these impacted population levels

define adaptability

the degree to which a species can survive and reproduce in different environments

define niche

a niche is the environment and way of life of a species

greater overlap in niches leads to greater competition

what is optimal foraging theory

links to niches - considers the best strategy to survive i.e. if there are lots of animals in overlapping niches, maybe it is better to evolve to occupy a different niche.

examples of humans adapting to niches

1. sickle cell anaemia - developed as a resistance to malaria

2. the carpentered niche - humans living in a world of corners has lead us to develop an illusion where different lines represent inwards or outwards facing corners

explain what ultimate causation and proximate causation are

ultimate causation = evolutionary levels of explanation - explaining why a phenomenon exists

proximate causation = explains how a phenomenon works using immediate circumstances i.e. our genes or environment

what are Tinbergen’s 4 questions regarding how traits arise

ultimate (why questions)

1. function?

2. evolution?

proximate (how questions)

3. development?

4. causation?

1. function

what the purpose of the trait is

2. evolution question

phylogeny (the study of our evolution to see connections amongst ancestors)

looking at the evolutionary history of a trait

3. development question

looking at the ontogeny (development) of a species to see where traits vary throughout development

4. causation question

looking at the immediate circumstances that tigger a behaviour

i.e. stimuli that elicit a response

what kind of traits can convergent evolution produce

analogous traits

what traits does adaptive radiation produce

homologous traits

what is the founder effect

it is when a new smaller population (coming from a larger one) has heightened levels of certain traits due to it’s lack of genetic diversity

what causes traits to appear blended

pleiotropy

codominance

incomplete dominance

what is pleiotropic vs polygenetic

pleiotropic = one gene influences multiple traits

polygenetic = multiple genes influence one trait

why should we study non-human primates

we share 98% of our dna with chimps and bonobos

and since we are both in the primate order, we can look back at their traits to see which of our traits could be homologies

why should we not compare humans with non-human primates

huxley vs wilberforce:

debate in victorian england - people were concerned with the idea that we could be related to another species

scopes monkey trial:

teacher on trial for teaching evolution when it was illegal to do so

when did dinos go extinct and primates formed

65 mill years ago

when did homo sapiens develop

300 k years ago

what is adaptive radiation and what did it produce

when a species branches off and starts rapidly differentiating

it caused the development of loads of new animals including primates!

name the main epochs (geological periods of time) relating to primate development

1. eocene

2. oligocene

3. miocene - 23-5 million yrs ago - monkeys and apes flourished

4. pleiocene - 5 million yrs ago - monkeys have now overtaken apes in numbers

what is taxonomy

defining and organising organisms in hierarchal structures

what are some defining characteristics of a primate

opposable thumbs and big toes

flat nails - no claws

locomotion is hind limb dominant

dry nose

forward facing eyes

binocular vision

what are some flaws in the primate taxonomy

aye-ayes have claws but are primates

pandas have opposable thumbs but are not primates

not all primates have dry noses

cats have forward facing eyes

what are the key features of binomial nomenclatures (Carl Von Linne) plus name for humans and chimps

genus (family) is uppercase and comes first

species (smaller category) is lowercase and last

italicised if typed

underlined if written

i.e. Homo sapiens, Pan troglodyte

name the class, order, family, genus then species of humans and chimps

class - mammals

order - primate

family - hominids

genus - human = homo, chimp = pan

species - human = sapien, chimp = troglodyte

name the primate order

1. hominoidea - superfamily, lesser and great apes

2. hominidae - family, great apes

3. homininae - subfamily, homo, pan, gorilla

4. hominini - tribe, homo, pan

5. hominina - subtribe

name all 5 great apes

1. humans

2. chimpanzees

3. gorillas

4. orangutans

5. bonobos

what does arboreal mean

living in trees - most primates are arboreal

give reasons why primates could be considered ‘slower’ than other animals

they have smaller litters (of 1)

longer pregnancies

longer childhoods

longer lifespans

name and define 4 different social structures primates live in

1. solitary - orangutan. males live alone, females live alone with infants

2. monogamy - one male and one female

3. polygyny - gorillas. one male, many females and infants

4. polyandry - bonobos. everyone mates with everyone

name and explain the two types of competition

1. contest competition

• caused by clumped resources

• more dominant = more resources

2. scramble competition

• caused by dispersed resources

• primates run around to find resources

draw a diagram of how socioecology can influence social systems

describe how chimps and bonobos differ in behaviour

chimps:

• resolve conflict through aggression

• won’t share food

bonobos:

• resolve conflict through sex

• happily share food

describe how chimps and human children differ

chimps and humans (2-3 yrs) have the same physical learning skills i.e. tool use

chimps have worse social learning skills - i.e. won’t take cues from others

there is some evidence to suggest they do have some kind of implicit theory of mind - experiment where gorilla hides and they look to where the gorilla used to be

name 4 key characteristics of humans

1. bipedal locomotion

2. larger brain:body ratio

3. slower development - longer childhoods

4. language and culture

when and why did bipedal locomotion evolve (give 4 reasons)

evolved 6-7 million years ago in the australopithecines

made ground movement easier - more efficient

good for long distance

helps keep us cool (wind exposure, less solar radiation, further from hot ground)

keeps hands free for carrying and foraging

state when australopithecines were around

developed in the pliocene epoch 4.2 million years ago, around during the pleistocene epoch (2.6 mya - 12 ka)

what are key features of australopithecines + lucy

bipedal

sexually dimorphic

smaller brains (400 cubic cm)

used oldowan stone tools (mode 1)

lucy is the most famous australopithecine fossil, proof of her bipedal nature is found in footprints in volcanic ash

name the epochs

eocene

oligocene

miocene

pliocene

pleistocene

anthropocene

when was the genus homo around

2.8 mya

homo erectus

early form of homo

pleistocene had a variable environment, which favoured larger brains (800 cubic cm)

brain size doubled from australopithecines

body grew from 5ft - 6ft

shorter childhoods (more similar to apes)

tools become more complex - acheulean (mode 2) i.e. hand axes

homo heidelbergensis

around 1.3 mya - 600 ka

bigger brains - 1200 cc

more complex tools - levellois technique (mode 3)

detail brain sizes of all homo

homo floresiensis - 370 cc

australopithecines - 400 cc

homo erectus - 800 cc

homo heidelbergensis - 1200 cc

homo sapiens - 1450 cc

homo neanderthalensis - 1520 cc

homo neanderthalensis

600-33 ka

adapted to colder climates (europe)

shorter and stockier than modern humans

even bigger brains than us - 1520 cc

developmental patterns similar to us (length of childhood)

language - fox b2 gene and hyoid bone present, both linked to flexible vocals and language

complex tools to hunt large prey

care for sick

bury dead

homo sapiens

physically developing in africa at the same time as homo neanderthalensis (300 ka)

mentally human around 40-50 ka with art and jewellery appearing (some jewellery evidence from 130 ka)

mode 4 tools used

shelters built

dogs domesticated

ritual burials

arts and crafts

neanderthals and homo sapiens interbred - what are neanderthal genes associated with

schizophrenia, more belly fat, risk of sunburn,

homo floresiensis

found on island flores in indonesia 18-14ka

brain is 370 cubic cm

3 ft tall

more 4 tools used

denisovians

found from one pinky bone discovered in a cave

not neanderthal nor homo sapien so must be another ?

dated to 41 ka

draw and explain the multiregional hypothesis

humans evolved from homo erectus in one location 2 million years ago

they moved to different parts of the world forming different groups (europeans, asians, africans, australasians)

suggests our groups are more distinct

draw and explain the out of africa hypothesis

modern humans evolved around 200 ka

multiple waves of migration with lots of mixing genes

suggests different ethnicities are more similar because the evolutionary branch isn’t as long ago

explain how differing levels of genetic diversity relates to the out of africa/african origins hypothesis

great apes all have more genetic variation than we do, and there is more genetic variation within africa - supporting the african origins hypothesis (because as we migrate from one place we go through population bottlenecks - reducing variation)

name 3 ways of gaining food

1. collected food - i.e. fruit picking

2. extracted food - i.e. termites from ground

3. hunted foods

why do humans hunt more than chimps

1. hunting is more cognitively challenging than collecting

2. expensive tissue hypothesis - meat requires a smaller gut to digest, meaning we have more space in our bodies for brain matter.

• brains are also expensive tissue - they require lots of energy, meat gives us this energy easily

how does age relate to hunting

men reach peak hunting efficiency at 50

however they reach peak strength at 30

suggests knowledge plays a key role i.e. being able to detect tracks

why do we hunt in groups

hunters have a far higher chance of success if they hunt in groups, so less chance of starving

we often hunt prey larger than we can eat alone before it would go bad

so we hunt in groups and share to allow us to eat meat

what has complexity of foraging tasks favoured

larger brains and slower development (so we have time to learn the skills)

what has food sharing and division of labour favoured

reduced sexual dimorphism

give evidence for sex differences in toys

female monkeys preferred to play with dolls

male monkeys preferred to play with trucks

state differences in male and female chimp behaviours

males:

• better at mental rotation tasks (turning an object around to see it from another angle)

• engage in more rough and tumble play

females:

• more attentive social learners

• carry sticks around like dolls

issues with having sex

meiosis has a cost - only half your genes get passed on

courtship has a cost - you have to find and court a mate before you can mate

explain fisher’s principle on keeping the ratio 1:1

a sexual population should produce an equal number of male and female offspring

this means the rarer sex is at an advantage - ensuring the ratio is kept at 1:1

explain the red queen hypothesis on why we have sex

parasites can evolve quickly, so we need to adapt just as fast to keep up resistance to them

sexually reproducing populations are better at overcoming bacteria and parasites because it changes the host and keeps high host variation

increases our genetic variability

explain muller’s ratchet

we have sex because asexual populations are at risk of developing harmful mutations

explain sexual selection

the differences in individuals in mating success

runs against natural selection because sexually selective d

features aren’t always cost effective for SURVIVAL i.e. male peacocks having huge flamboyant tails

what is sexual asymmetry

the differences between males and females in reproduction

females have large gametes, that are expensive. so they are choosier since their investments are higher

males have smaller and multiple sperm, so they are cheap

what is anisogamy

the differences between male and female gametes

sperm vs egg

intrasexual selection

competition within a sex

males competing with other males for access to females

intersexual selection

mate choice

females choosing a mate based on desirable traits

runaway selection

mothers choose a mate based on desirable traits

daughters are more likely to choose these traits too

sons are more likely to display these traits so they get chosen