Primates, hominins and bipedalism

what is biological evolution

the transmission of genetic material from parents to offspring from generation to generation

what are examples of genetic material

• DNA

• genes

• alleles

• chromosomes

where do new alleles result from

gene mutations and the alleles that enter the gene pool are subject to natural selection

how is the rate of biological evolution determined and what is the rate

• it’s random and tends to be slow

• rate determined by mutation, natural selection and environmental changes

important trends in the biological evolution of humans

1. skeletal changes linked to bipedalism

2. changes in the skull and endocranial features

3. changes in the manipulative ability of the hand (manufacture/use of tools)

what does endocranial features refer to

the volume of the cranium → indicator of the size of the brain

what is cultural evolution

the transmission of learning knowledge between and within generations

what does knowledge result from/ stored in

• results in a higher level of thinking

• stored as memory, written form

• can be transmitted by language which is both spoken and written

what does knowledge include

• ideas

• beliefs

• customs and values

what are examples of cultural evolution in form of human lifestyle

1. tool technology

2. controlled use of fire

3. food-gathering techniques

4. settlements and farming

5. language and communication

6. art and music

what is the rate of cultural evolution

it is directional and tends to be rapid

what are important trends in the cultural evolution of humans

1. manufacture and use of tools eg. stone, wood and bone

2. (controlled) use of fire

3. clothing

4. abstract thought → communication, language and art

5. food gathering → hunter-gathering, domestication and farming of animals

6. shelter → caves (temporary/ permanent settlements)

when does cultural evolution accelerate

with the development of a complex brain and an ability to communicate

what does race refer too

the physical characteristics of a person eg. skin colour, body build, hair colour etc.

result of biological evolution

what does ethnicity refer too

factors such as language, lifestyle, beliefs

all learnt + result of cultural evolution

what are primates

a group of mammals in which humans, the great apes, monkeys and some other families eg. lemurs belong

characteristics of primates

• have a large brain relative to body size

• strong binocular vision

• forward facing enclosed eye sockets

• colour vision

• mobile fingers and toes

• sensitive finger pads

• reduced sense of smell

what are hominids

the family of primates that include the great apes and humans

characteristics of great apes

• large tailless primates

• males are usually larger and stronger than females

• mainly quadrupedal

what is quadrupedal

habitually walk on four limbs

what is anthropoid

resembling a human

what are hominins

a subfamily of the hominids that includes all living and fossil species belonging to the human lineage

what are the three genera of hominins

1. ardipthecus

2. australopithecus

3. homo

how has the biological evolution of humans occurred

through natural selection:

• the best-adapted individuals surviving and passing on their successful alleles to their offspring

• these alleles subsequently increase in frequency in the gene pool (microevolution)

what was the starting selection pressures 5 mya (million years ago)

African climate changed:

• became cooler and drier

• dense forest gave way to open savannah (grassland + scattered trees)

• seasonally dry and hot conditions

what did the change in African climate cause

• selection pressures for changes in climate and habitat resulted in different adaptations being selected for

• early hominin populations began to diverge from ape-like, arboreal ancestors

what does arboreal mean

tree dwellers (inhabiting trees)

what is the defining characteristic of hominins

bipedalism

what does bipedalism mean

a form of terrestrial locomotion where an organism moves by means of its two rear limbs or legs

• habitually walking on two legs

how is bipedalism significant in human evolution

it’s likely that it was the main driving force for subsequent hominin evolution

how are humans described vs apes

• humans: gracile, slender and lightly built

• apes: robust, stocky and heavily built