Define classification, taxonomy and taxa:
Classification: arranging organisms into groups based on relatedness
taxonomy: the science of classification
taxa: groups of organisms with shared characteristics
taxonomic hierarchy / classification: (for humans)
domain- eukarya
kingdom- animalia
phylum- chordata
subphylum- vertebrata
class- mammalia
order- primates
superfamily- hominoidea (hominoids)
family- hominidae
tribe- hominini
genus- homo
species- H. Sapiens
Shared features of mammals (class):
- fur or hair
- milk-producing mammary glands
- give birth to live young
- teeth comprising of: incisors, molars, premolars, canines
- lower jaw made of a single bone
- three bones in the middle ear
- diaphragm separating chest cavity from abdomen
Shared features of primates (order)
- no dingle characteristic means that it is a primate but together the following features can help identify one
hands and feet have:
- five digits that can grasp objects
- opposable thumbs (allows grasping of objects)
- sometimes opposable large toe
- flat nails on digits
binocular vision:
- large, forward facing eyes that give stereostopic (3D) vision
- colour vision (3 types of cone in retina of eyes)
- large brains relative to body
- long gestational period
- social animals, live in groups
hominoidea: superfamily
- members of the superfamily hominoidea: hominoids
- include great apes (orangutans, chimpanzees, bonobos, gorillas) and hominins (humans)
- include lesser apes (gibbons, siamangs)
shared features of hominoids: (superfamily- hominodea)
- absence of tail
- larger, more complex brains
- molar teeth in lower jaw with five cusps
- long upper limbs
- wider chest
- shoulder joints- allow arm to rotate
Define hominins and shared features: 1 skull, pelvis, spine
- members of tribe hominini
- modern human species and extinct close relatives that could walk with bipedal locomotion
main feature: bipedal locomotion (can walk erect on two hind legs in a sustained way)
feautres that allow bipedalism:
- foramen magnum: hole at the base of the skull has become more central and more forward (allows for vertical alignment of head and neck)
- the slope of the forehead became more vertical
- shape of pelvis: more bowl shaped, shorter hip bone
- shape of spine: S shape- provides flexibility, acts as spring, spine acts as shock absorber and helps with weight distrubtion (other hominoids have C shaped spine)
Define hominins and shared features: carrying angle, legs, feet
- arrangement of femur and tibia: angled
- carrying angle of femurs are more angled compared to other great apes (helps align the knee and maintain balance)
- greater leg: arm ratio- allows humans to remain erect and upright
feet: better support weight
- larger heel bone and heel arch
- hallux (big toe) in line with other toes, not opposable
hominin evolution trends
- larger, more complex brain
- reduced teeth size, teeth have more uniform shape
- more parabolic, rounded shaped dental arch
- flatter face
smaller zygomatic arch (cheek bone)
less prominent brow ridge
(reflect change in diet to softer, cooked foods)
why is there uncertainty concerning the timeline of human evolution?
- fossil record is incomplete
- fossils may be incomplete or only small fragments found
- as new discoveries of fossils are made this can alter previous views
- uncertainty as to whether individual fossils are from a different species, or due to variation within a species
- several species may have co-existed and interbred
Evidence for hominin interbreeding, what it challenges
- DNA analysis indicates interbreeding happened between hominin species
- challenges understanding that different species could produce fertile and viable offspring
Neanderthals:
- share 99.7% of DNA
- Europeans and Asians share 1-4% of mtDNA while Africans share 0%
Denisovans:
- share 17% mtDNA with neanderthals, indicating they interbred
- share 4-6% of nuclear DNA with Melanesians and Indigenous people of Australia
Out of Africa theory vs multiregional theory
Homo Sapiens evolved in Africa, then moved out of Africa to other continents in two waves at different times
Key evidence: current humans have very little genetic diversity
- greatest diversity in Africa, as more time for mutations to accumulate
- Homo Sapiens evolved from Homo Erectus IN Africa.
- evolution occured IN africa, not in mutliple regions worldwide
multiregional theory: Homo Erectus migrated out of Africa and evolved in different locations.
Ancestral hominin migration
2-1.75 mya:
- Homo erectus (or possible an unknown Homo species) were the first homins to leave Africa.
- they had larger brains, made tools, had diet that included meat
1 mya:
- Other hominins moved from Africa into Asia
- may have been movement back into Africa
900 000 ya:
- Homo heidelbergensis (ancestors of neanderthals) moved out of Africa to Europe
- with different environents / natural selection, evolved into neanderthals (300 000 ya)
Evidence for where early hominins evolved
- mtDNA evidence suggests hominins evolved in Africa
e.g. - Australopithecus genus and early members of Homo genus (homo habilis) existed only in Africa (as their fossils were only found in Africa?)
1st wave of migration:
- 160 000 - 100 000 ya
- homo sapiens migrated from north-east Africa to middle east
- two way migration may have occurred (back to Africa)
2nd wave of migration:
- 60 000 - 40 000 ya
2 hypotheses:
1. After first wave, modern humans migrated further north west (FROM middle east into Europe) and further south east (into asia)
evidence: - stone tools found and dated (UAE, Yemen, India)
- no hominin remains have been found
- second group of hominins moved FROM Africa into Europe and Asia
evidence:
- fossils of hominins (cro magnons) found in French cave
- comparison of skeletal structure: more similar to modern Africans than modern europeans
- led to arrival of Indigenous populations to Oceania
- includes ancestors of Aboriginal Australians
evidence for 2nd wave:
- art and culture: carvings, cave art dating back to 2nd wave
- shows the evolution of the way homo sapiens lived and of their social interactions with others and the environment
when did Aboriginal populations migrate to Australia
- new evidence suggests arrival of the ancestors of Aboriginal Australians happened 65 000 years ago
Aboriginal viewpoint on migration: THe Dreaming
- a system of belief of many Indigenous Australians of their origin
- Before the dreaming, the land was flat
- in the Dreaming, all-powerful beings moved across the land, shaped the natural world (e.g. mountains, rivers). gave rise to the “first people” and established moral laws and customs
- Aboriginal people have been present in Australia since the time of creation
- knowledge of their history is ingrained in their blood and Country
- westernised view that they arrived 65 000 ya diminshes their Connection to Country
Ancestors of Aboriginal Australians: lake mungo
- oldest human remains found in Australia (42 000 - 40 000 ya)
- it is believed they arrived at the lake around 42 000 ya, found diversity of plant and animal life
- evidence indicates they built fires, painted their bodies, developed tools in this area
evidence of cultural practice:
- most famous body uncovered: Mungo Lady- ritualistically buried
- next body: Mungo Man: ritualistically buried
- these remains were returned to Aboriginal communities- important for their Connection to Country and their history
evidence of cultural practices: devil’s lair
- artefacts including bone points, beads and plant remains
- indicates cultural evolution of Noongar people living in region 40 000 ya
hominin timeline
- australopithecus
- homo habilis (first used stone tools)
- homo rudolfensis
- Homo erectus (first used fire)
- homo floresiensis
- homo hiedelbergensis
- H. naledi
- homo neanderthalensis
- denisovans
- homo sapiens
