u4 vce bio ch11 human change over time

mammals, primates, hominoids, hominins, trends in hominin evolution, important hominins, cognitive change in human, important examples of homo, fossil record and human migration

mammals

• fur, exocrine glands secrete fluid (mammary, sebaceous, sweat glands), endothermic (regulate body temp), 4 chambers in heart, diaphragm, single bone lower jaw, teeth (incisors, canines, molars), 3 bones in middle ear

viviparous

• marsupials → embryo nourished by yolk placenta and born at early development stage

• placental mammal → placenta connect nutrients and born with developed org

oviparous

• monotremes → lay eggs and feed off skin fold with milk.

primates

humans, apes, monkeys

• 5 digits & grasp objects

• opposable thumbs

• flat nails

• stereoscopic 3d vision & see in colour

• large craniums and large brains relative to body size (on graph we above the line meaning big brain small body)

• rotate arm shoulder socket

• sexual dimorphism

hominoids

humans, gorilla, chimp, orangutans

• hominoid brain large & complex

• long limbs compared to legs

• DONT HAVE A TAIL

• 5 cusp molar teeth

hominins

human or any ancestor that can walk on two legs

• bipedalism 

trends in hominin evolution

• brain larger, face short & flat, teeth & jaw smaller, legs longer compared to arm, feet longer & arches, being bipedal became more upright overtime and not hunched

foramen magnum & pelvis & femur & spine & foot

foreman magnum

opening on underside of cranium where spinal cord enters. The position determines how org walks.

• more towards front = upright

• gorilla → more at the back

• the trend is it became more central

pelvis

more short & wide bowl shaped. Allows for balancing on one leg when walking.

• distributes body mass

• allows for more attachment sites for butt muscles

• long narrow pelvis = no balancing

femur

• become more angled so knees & feet more under body centre of gravity, giving balance when walking

spine

• becomes s shaped, head balances on spien and allows even distribution of weight & flexibility. Apes have c shaped spine

foot

• lost prehensile capacity (grasp), human foot has heel as shcok absorber, arches to reduce energy needed to walk and transfers weight across foot via arch to big toe that pushes off 

advantage of bipedalism

• easier to view objects at distance

• reduced absorption of heat from sun bc smaller sa exposed

• walk greater distances & less energy used

• posture free up hands to carry objects

ardipithecus (genus)

ardipithecus 4.4mya

• very early hominin

• teeth are ape-like → omnivore eat on hard stuff = big teeth

• arm ape like bc its long but human like bc has thumb to pick up things easily

• live in shady forest so long arm to swing

australopithecus genus

• 4-2mya

• primitive hominins, we descend from this.

• bipedal but not upright

• small brain, large teeth, wider pelvis, long arm to leg ratio

australopithecus afarensis LUCY (this sis as lucy girl)

• 3.9-2.9 mya

• slender build

• in africa and direct ancestor of homosapiens

• bipedal, climb trees, grasp due to their curved toes & fingers

• reduced canines & molar teeth but larger than humans

• small brain, projecting face

• pelvis more human like

• femur angled 

• large sagittal crest for powerful jaw muscles

australopithecus africanus

tuang child

• slender build

• human like cranium for bigger brain, and foramen magnum more towards middle

• rounded jaw

sexual dimorphism, diet

sexual dimorphism

• females smaller compared to males

diet

• australopithecines ate vegetable stuff which is hard so had larger jaw muscles (ZYGOMATIC ARCH & SAGITTAL CREST ALLOWED FOR MORE MUSCLES TO ATTACH)

• large digestive tract = larger waist & rib cage to fit larger gut

genus paranthropus

p robustus and p boisei (nut cracker)

• large jaw, ate nuts

• pelvis similar to australopithecus = bipedal 

africa and fossils found

cradle of humanity

• oldest prehuman hominin fossil found in africa and any other fossil found outside of africa is not as old as it meaning we all from africa.

hominin and genus homo evolution

Evolution of genus homo is linked to structural and cultural changes. Starting from 2.8mya after appearance of first homo species.

• complex cognitive skills

• use of fire, group activities, caring for old, burying, art & music, symbols, inc use of tech using tools by homo habilis

human hands

being bipedal (came first) allowed hands to be free to carry and we didnt use body weight

• hands adapt for manipulation

• hands became wide and short compared to primate its long to grasp branches

• human hands have precision grip to manoeuvre small objects compared to power grip it cant

biological evolution

changes in humans due to natural selection and inheriting phenotypes

early homo species were diff from australopithecus showing:

• inc brain size, inc cranium size

• dec size of teeth & jaw muscles due to food is cooked & softer = chew less (small zygomatic arches)

• dec in eyebrow ridges to accomodate inc size of brain

• flat & short of face making it vertical → didnt need large face to digest food cause it was cooked

• parabolic jaw shape

• leg longer compared to arms bc walking not climbing

younger = larger cranium

expansion of cranium

led to inc cognitive capacity and cerebral cortex, outer most region of brain → inc folding (convolutions)

prefrontal cortex is larger for cognitive capacity to inc

cognitive capacity → org innate ability to learn, play, evaluate, make new knowledge and apply new knowledge

large cognitive capacity allowed us to learn language to communicate, work in groups, make jewelries.

non-structural evolution of hominins

eating meat in fire gave protein & energy for brain growth.

brain capacity inc → cognitive abilities inc

made it a strong selection pressure in problem solving and planning, better survival advantage

can hunt for survival, inc brain capacity separates genus homo from australopithecus

larger brain led to cultural and technological evolution

cultural evolution & tech evolution

culture → any form of learned behaviour overtime. Make tool, social rules, play, through imitation or teaching.

enhanced through tech.

cultural evolution → changes in human societies overtime, changes are socially transmitted not genetically transmitted

tech evolution

• change in what tools we used and how its made

greater reliance on meat = teeth smaller bc meat less chewed.

cooking/grinding/cutting food dec canine sizes and molar for tearing.

canines can be used for aggression by other apes

eating meat = more free time = socialise, learn skills, energy for brains

homo habilis (handy man)

2.4mya

• first to use tools

• transitional fossil of australopithecus and genus homo

• found in africa

• large brain, smaller teeth than australopithecus

• shorter arms, bowl shaped pelvis

homo erectus (upright man)

2mya-300k ya 

• outside of africa

• used fire → warmth, fook meat

• better tools, made noise no speech

• protuding jaw and marked brow ridges

• buried the dead = cultural evolution 

• foramen magnum more centrered bc hes upright posture 

homo floresiensis (the hobbit)

100k-18k ya

• overlapped with homo sapiens

• used tools & fire

• small brain and evolved from homo erectus on small island

• doesnt follow the trend of bigger brain

homo heidelbergensis

400k-40k ya

• intermediate between homo erectus and homo sapiens

• larger brain than homo erectus, fossils found outside of africa

homo neanderthalensis

150k-35k ya

• not ancestors of homo sapiens but cousins and lived same time

• larger brains, slope forehead brow ridges

• fine tools, clothing

• 1-4% of dna of all non african modern humans come from neanderthal = human interbred with them

• native africans dont have neanderthal dna

• died out due to competition or disease 

homo denisovans

40k ya

• only bone fragments 

• mtdna extracted and closely related to neanderthal but make them diff species

• human interbred w homo denisovans bc dna found in papua new guinea and interbred when migrating to south east asia

homo sapiens (knowing man)

• larger cranium

• flatter face

• lighter & parabolic jaw

• smaller teeth

• anterior foramen magnum

• larger heel bone

the fossil record for humans

its incomplete bc:

• fossilisation rare event, hominins didnt live near water for fossilisation and we buried away from water. We havent been around for long

complete fossils of an incomplete specimen due to washed away before fossilisation happened → skull no body incomplete bc rest of the bones r missing

OR incomplete fossil of a complete specimen where whole thing fossilised but earth movements happened → parts of a bone but u have most of the specimen.

Record is bad bc:

• scavengers break specimens before its fossilised.

• lack fossils to complete human evolution story, some havent been found yet

• early human way of life is inferred by surroundings around fossil

• diff scientists and paleontologists interpret the record & evidence differently 

• dna hybridisation cant always be used esp on old fossils bc dna is decayed (cant compare the dna)

always changing

• bc new fossil found it changes where other fossils sit, can discover if there was interbreeding eg human & neanderthals

• comparitve genomics help give evidence of denisovans and interbreeding between other hominins.

h floresiensis issues around its fossil

• the fossil remains are dated thousands ya but surrounding deposits show its older so its age is interpreted diff

• h floresiensis evolved from h erectus due to skull similarities and brow ridges but it evolved to be smaller after ancestors on an island so its origin is unknown

• dwarfism made them short bc of restricted food supply on island and limited predators, making brain small. 

out of africa theory - migration

• homosapiens evolved in africa and then spread out

• isolated populations out of africa had no gene flow, hence natural selection and diff races

• homosapiens replaced h.erectus or interbred w them

• h.erectus led to neanderthalensis and then bred w homosapien in europe

• neanderthal dna is from ppl outside of africa and africa has most variation due to longest time being there for mutations to occur

haplotypes and haplogroups

mtDNA used to look at evolutionary lineage bc its interrupted inherence and constant rate of change.

haplotype→group of alleles org inherited togerht from single parent

haplogroup → population group of ppl who share similar haplotype inherited from a common ancestor

• all haplogroups start as og haplogroup in africa and mutations caused new haplogroup
  - lots of variation in africa bc longest time for mutation to occur compared to countries outside of africa less diversity

genomic evidence 

nuclear genomic sequences show humans outside africa share common ancestry. 

migration of australia

low sea levels connected it to new guinea and tasmania so it had genetic variation bc of gene flow at north and south australia

can also look at indigenous languages diff languages bc sea levels rose and diff populations occurred and archaelogical evidence shows remained in contact w the diff areas

indigenous farming

to manage land for sustainable food supply

fire stick farming to stabilise landscape, control local food supply of plants & animals

change composition of plant & animal species, weed control and inc biodiversity

water channels connected to ponds to trap eel at diff stages of growth

went from hunting to farming showing cognitive capacity inc.