3.6 Human Evolution

Biological evoluation

The changes in genetic informaton through the transfer of DNA from one generation to the next.

Occuts slowly compared to cultural

Scapula

A and H both have scapula on the back and side of the rib cage

H scapula is further back with different angles becuase hanging not required

Allows better throwing power and accuracy, reduces upper body mass, keeps COG over base support

Hunting advantage, more effiect, surival, repro

Rib cage

A barrel shaped extended outward (deeper)

H flatter and broader

Allows skull and upper body mass carried directly above hip joints, COG over base support, balance (bipedalism)

Spine

A c shape

H s shape

Allows skull and upper body mass carried directly above hip joints, COG over base support, balance (bipedalism) and efficicency walking on two legs

Pelvis

A longer narrower

H shorter wider (bowl shape)

Allows better support of mass over COG, balance (bipedalism), support upright structure and leg movement

Femur / legs

Valgus angle

A short femurs, little to no valgus angle

H long femur, increased valgus angle

Increased stride length, brings knee under pelvis, COG support directly above knee, balance (bipedalism)

Arms

A longer arms

H shorter arms

The shift to bipedalism, no longer need long arms for climbing

Tool use

Knee joint

A smaller knee joint, less lateral buttressing

H larger knee joint, more laternal buttressing

Prevents lateral movement of joints when load increases during bipedalism

Feet

Arch

Big toe

A feet on outer side of pelvis, no arch, opposed big toe

H feet directly under pelvis, arch, foward facing big toe

Feet under spine for COG support and balance of weight transfer when walking

Arch acts as shock absorber for weight transfer

Big toe in line improves weight transfer, heel to toe, thrust off big toe

(bipedalism)

Foramen magnum

A towards back of skull

H center of skull

Allows Hs heaveir skull to balance ontop of spine, less muscle and energy required to keep up and face eyes foward

(bipedalism)

Bipedalism

“This resulted in improved efficiency (bipedalism) of walking on two legs, and so able to save energy which can be used for other things such as getting resources, brain growth, reproduction. Therefore, increasing survival chances and reprouctive sucess, allowing the ability to pass on faveourable alleles more often sucessfully and this increasing the sucess of the species”

Bipedalism advantages

LTGHT

• Efficent locomotion - homins can walk further in search for food/water

• Thermoregulate - less exposure of body to sunlight, boday stays cooler in hot African Savannah

• See over gress - upright position spot prey/predators

• Free hands - carry resources/tools/weponds (save energy spent making)

• Tools/weponds - upright stance weilding stick and throwing stones (hunter gatherers)

More likey to survive, life process carried out, reprodue, passing on bipedal alleles to next generation, increases in frequency in population over time

Jaw muscles

A larger

H reduced

A change from tough plant based diet to a softer protien diet with more energy and nutrients meant large jaw muscles were not selected for since forces of chewing now necessary

Energy can be used on other things such as growth, reproduction, gathering resources

Teeth

A larger canines and molars, u-shaped dental arcade, and a diastema (gap)

H smaller teeth, v-shaped dental arcade, no diastema (gap)

A change in diet…… smaller jaw size, selected for smaller teeth and v-shaped dental arcade because helped with processing cooked food.

Large canines not required for threat displays and sexual dimorphism

Smaller jaw = no diastema

Energy can be used on other things such as growth, reproduction, gathering resources

Hand - fingers and tumbs

Occured after bipedalism when hands were free to evolve

A long curved fingers, shorter thumb = POWER GRIP

H shorter straighter fingers, long opposable thumbs = PERCISSION

Power grip

• the abiliy to have a clap-like formation around an object

• the fingers and palm are particularly fixed

• pressure is applied by the thumb

• grip allows more force to grasp bra

  

  ches

Percision grip

• the ability to preform fine manipulative movements

• opposable thumbs and fingers allowed accuracy

• more specilised tools

• greater access to protien rich diet providing energy and nutrients

• brain development (e.g. increased cerebelum for fine motor control)

(e.g. later homins able to develop and use tools becuase has more active strike)

Change in enviroment on bipedalism and hand evoluation

• africa 6mya climate became warmer and dryer

• forests receding to scattered wooded savanah

• more open habbitats, food resources become dispersed

• reduced need for branchiation, selected for locomotion (bipedalism)

• hands no longer needed to support weight, free to make/use tools/weponds

Cerebellum

A small

H highly developed

Change in diet…. energy for brain development, and upright (bipedalism) increased cerebellum size

Fine motor skills, balance, and manipulative momements

Tool development and easier access to food = more brain growth = increased survival

Wernickes area

Developed in H brains

Change in die = energy = brain development AND increased group living selecting for communicaiton

The understanding and comprehension of spoken language

Improved comms, teaching and learning, cooperation, tool development, improved hunter gatherer

survival, repro sucess, passing on fave alleles, species sucess

Brocas area

Developed in H habilis brains

Change in die = energy = brain development AND increased group living selecting for communicaiton

Language processing, speech production, comprehension

Improved comms, teaching and learning, cooperation, tool development, improved hunter gatherer

survival, repro sucess, passing on fave alleles, species sucess

Frontal lobe

Abstract thought, foward planning, imagination, inovation, social control

Cranical capacity / expansion

A 400-500 CC

H 1350 CC

A change in diet = energy for brain development and growth

Free manipulative ability, free hands, social groups, co-op selected for bigger brain with more folding (especially in frontal lobe)

Englarged brain = increased abstract thought, thinking, planning = better resource gathering / tools / hunting = better survival

Multi regional theory

Suggests that H.erectus migrated out of Africa 1.5mya and evolved into H.sapiens simaltaneously in Africa, Europe, Asaia through constant gene flow of neighbouring populations

Multi regional evdience

Fossil

Transitional fossils found outside of Africa represent intermediates between H.erectus, Neanderthals, H.sapien

Suggests the physical diffs between them are due to diff selectiom pressures in diff regional differences

Suggests H.sapien evolved from H.erectus outside of Africa (gene flow occured)

Multi regional evdience

mtDNA

Neanderthals mtDNA is substainaly different from modern H.sapien

Suggests N was a diff subspecies but belonged to the smae species as anatomicaly modern Hominins

Multi regional evdience

Nulear DNA

Some similarities in DNA sequences of Neanderthals, H.sapien, H.donesivans

Suggests interbreeding did occus, supports gene flow occurance between regions

Out Of Africa (OOA)

Suggests that H.sapiens left Africa 65,000ya (having evolved from H.erectus) and replaced early hominins such as H.erectus, Neanderthals, Denoisvans present in other parts of the world.

No gene flow between Afrian, Asain, European populations

OOA evdience

Fossil

The oldest H.sapien fossil in Africa 200,000 - 300,000ya

Found at the same time as H.erectus and Neanderthals

Therefore they existed at different pops

Suggests that evoluation occured in Africa

OOA evdience

mtDNA

• mtDNA is inherrited maternally

• used as molecular clock

• doesnt undergo recombination

• only changed by random mutations that occur at a known constat rate

• able to work out time of divergance

Suggests the oldest living modern human 200,000ya in Africa based on the number of accumunlated mutations that occur at a constant rate in mtDNA

Suggests H.erectus evolved in Africa first

African populations are older than non-African pops

OOA evdience

Nulcear DNA

Nuclear DNA identifies specific genes, simalrites, determine shared traits, lineage connections

The further away non-African pops are from Africa = less GV

African pops = more recent origin = more GV

Older Africa pops = larger GV as more time for mutations

Suggests H.erectus evolved to H.sapein in Africa

Dispersal routes

• EAST - WEST migration, along coast and around equator

• route was faster and favoured

• warmer conditions which hominins were adapted to

• well resourced (seafood, freshwater rivers)

• south - north, through central Asia

• not favoured, slower due to terrain, colder, limmited food supply

• later migration into North America occured following ICE AGES where sea levels lower (glacial), land bridges form (bering straight from Europe to North America)

Cultural evoluation

Involves the transmission of knowledge from within one genetration or across generations

by teaching, learning, or passing on information that is not genetically derived

relatively fast compared to biological, can occur within one generation

Oldawan

• ~2mya

• Africa

• H.habilis

• Pebbles / stones

• Hard hammer percussions, 6 blows

• Large round rock, roughly flaked

• choppers, scrapers, flakes

• cutting, skinning, butchering, crack bones for marrow

• Supported H.habilis as scavenger

• Better process carcasses and access energy dense bone marrow

• Increase energy = fuel brain development

Acheulean

• ~1mya

• Africa and Middle East

• H.erectus

• Stones

• Hard and soft hammer percussions, 50 blows

• Bifacial, teardroped shaped, hand axes

• Butchering, chopping, scraping

• Cleavers, picks, hand axes

• Supported H.erectus shift to HUNTER GATHERER

• Incresed meat intake = brain development

Mousterian

• 200,000 - 40,000ya

• Africa, Middle East, Europe

• Neanderthals

• Flint and stone

• LEVALLOIS METHOD (preparing core, striking off large oval flake) 150 blows

• Tourtise-shell apperance

• SPEAR POINTS, hand axes, scrappers (dressing animal hides for clothing and tempory shelters)

• Supported N hunting capacity via tool making

• Allowed them to survive colder climates (Europe) to avoid

  competition, increase survival

  

Upper paleolithic

• ~50,000ya

• Everywhere

• Neandertals and early H.sapien

• Stone, wood, bone

• Soft hammer percussion, punch blade method, pressure flaking, 250 blows

• Spear throwers (kill prey from afar)

• Bone needles (stitch clothing)

• Fish hooks (costal exploration)

• More varied hunting tools

• Access to costal areas

• Diet variety

• Tailored clothes for cold enviroments

• Increase survival

Neolithic

• ~12,000ya

• Everywhere

• H.sapien

• Stone, bone, antler, flint, wood

• Pressure flaking, pollished stone

• Sickles, curved blades, secreeted edges, mounded handles

• Tools for agriculture (plant cultivation and animal donestication)

• Quern and rubbing stone = processing seeds grains

• Sickles and scythes = harvesting crops, cutting vegitation

• Hunter gatherer to AGRICULTURE FARMING

• Increased productivity, constant food supply, trade, specilised pollished tools

Fire advantages

Remain active at night:

extended hours, continue activity in dark / caves, tool making, communication, teaching of skills = productivity

Warmth:

allowed expannsion into cooler areas during ice age, migration OOA, less energy used for thermoregulation, energy redirected for brain development, teaching, consuming food etc

Protection + prey:

scare / burn / harm predators, defense increasing survival, heard prey

Cooking:

made meat easier to mechanically chew and digest, more nutrients high protien energy diet via improved hunting, energy for brain development, further improves tool making, communitcation

perserve meat via smoking decreasing rick of starvation

kill parasites and toxins (pathogens) reducing disease

Social interaction:

bringing food back to communal fire increased social interaction, further development of tool cultures, social organisation, hunting preparation, shake knowledge, plan, possible language development (in later homins)

Fire disadvantages

• Burning (injury)

• Ecological destruction

• Attract compeditors

• Increased work required

Spirituality

Art

• aligned dead bodies east - west

• legs curled sleeping posture

• head resting on stone

• decorated with red orche and black maganise dioxide flowers

• suggests concept of afterlife rituals spiritually

• development of frontal lobe = abstract thought

• jewlery, cave art