hominids and hominins Flashcards
primates
order of humans
evidence: fossils and comparative anatomy
humans:
primates-> haplorrhini->simiiformes->hominoidea-> hominidae-> homininae->homo->sapiens
primate characteristics
body, limbs: unspecialised
hands/feet: pentadactyl, nails, grasping ringers and gripping toes with friction ridges for gripping, first digit opposable
eyes: forward facing for stereoscopic vision, most distinguish colour
smell: poor sense of smell
teeth: 4 incisors in both upper and lower jaw
brain: large and complex, cerebrum size increase and primates evolved
reproduction: not restricted to breeding system, rhythmic sexual cycle, long period of parental care for offspring
hominids
family=hominidae
characteristics:
- larger more complex brain than other primates (increased cognitive ability)
- 5 cusps in molar teeth of lower jaw
- arms that freely rotate at shoulders
- wide, shallow chest cavity
- no external tail
- appendix
- diurnal
cerebral cortex
trend: increased in size
cerebral cortex: deals with vision, memory, reasoning and manipulative ability
arboreal environment led to large brain for body size: environment favours more accurate vision and tactile perception (more reliant on vision than smell)
frontal lobe had greatest enlargement: higher functions (problem solving, thinking, reasoning planning and processing)
strong pattern of convolutions: allow SA of brain to be greatly increased.
increase in cerebral cortex size
enable moving about, locating food, social skills, tool making
tool making (instead of make): requires predetermined image of what tool looks like, requires highly developed brain
greater variety of behavioural responses for variety of environmental problems
eg. grooming: reinforces relationships
large brain requires large cranium
cranial capacity
measuring volume inside the cranium using endocast
determines brain size
mobility of digits
primate limbs unspecialised leads to diversity in use
pentadactyl, very mobile ->arboreal environment
prehensile digits required for tree climbing
trend: increased ability to move digits independently of each other
opposability: (depends on length of 1st digit compared to the other 4)
human toe = not opposable
human have longest thumb
human hand: short, broad, straight fingers w/ long strong thumb
power grip
thumb and finger apply force to palm to transmit force to an object
precision grip
grasping object between thumb tip and fingertip
handling small delicate objects well
shows presence of truly opposable thumb
locomotion
quad->bi
humans: bipedal locomotion with striding gait
foramen magnum
hole where brain joins spinal cord
trend: moved forward to become more central
allows skull to balance
apes need large neck muscles to hold head in position, humans don’t (weight of skull borne by vertebral column)
spinal column curvature
c-> s
allow upright posture
improves balance upright, and allows head to balance
cervical curve in neck brings vertebral column directly under centre of gravity of skull
double curvature: lumbar vertebrae are wedge-shaped from front to back (forms forward jutting curve)
jaw
apes: protruding, humans: flat
reduced prognathism: skull balance
equal weight infant of and behind FM
pelvis
broad, short, bowl-shaped
BS: supports abdominal organs when standing erect
-> better stability for bipedal
broad hip bones: allow space for attachment of large buttock muscles-> move body, keep body erect
carrying angle
human: shape and orientation of pelvis means acetabulum right under trunk and head
- > allows body weight to be transferred to legs from pelvis
acetabulum further apart: femurs converge at knees
carrying angle: arrangement of thigh bones to form angle to vertical
-> ensures weight distribution remains close to central axis of body when walking
human: weight falls through outside of femur
-> enables striding gait: body rotated about lower leg and foot-> footsteps follow a straight line
better stability upright
knee
weight transferred to outside of femur to knee
knee joint: two part hinge joint (condyle)
-> hinge on either side of ligaments in middle of joint
thus: outer hinge larger and stronger since weight is transmitted there
centre of gravity: falls through a line in front of knees
- > thus: force that tries to bend knee backwards exists -> resisted by ligaments making up knee joint
- > natural resistance= joint that requires no energy to support erect posture
foot
weight: knee joint-> tibia -> talus-> tarsal bones-> metatarsals-> then phalanges via foot arches-> big toe
foot lost prehensility to become locomotory organ
big toe: large and aligned alongside other toes
metatarsals from transverse and longitudinal arch-> enables bipedal
centre of gravity
point where gravity is concentrated
human: lower centre of gravity-> have longer legs than arms that increase stride length
lower centre of gravity: stability when walking/standing
muscle tone
partial contraction of skeletal muscles
eg. head erect: back neck muscles are partially contracted
muscles that help with upright position:
- muscles that bring about movement of the spine, hip, knee, ankle
- abdominal muscles
- maintained by nervous system and sense organs
striding gait
walking upright that hip and knee are fully straightened
foot and striding gait
the foot:
- weight transmission: heel->outside of foot-> ball-> crosses ball via transverse arch-> big toe
- thus: final moment of striding: whole weight propelled by big toe
big toe lost opposability to evolve into weight bearing appendage
transverse arch is shock absorber
pelvis and striding gait
trunk rotates around pelvis whilst walking
-> forward swinging of arms compensates for natural rotation of body (right arm when left leg)
arm swinging: keep shoulder 90º to direction of travel and less energy expended. otherwise energy wasted in reversing rotation of body
femur arrangement and striding gait
converge at knee
stability whilst walking
body can be rotated about lower leg and foot
->weight distribution close to central axis
advantage of bipedalism
favours low speed and long distance
- energy efficient way of moving
- hands free (tools/carry items)
- greater height to see further
- less body exposed to sunlight
- increased exposure to breezes and increased cooling mechanisms
dentition
primates have deciduous and permanent teeth
dental formulas: number of teeth and shape
natural selection led to decrease in teeth number
-> reduction in face size and jaw that occurred in primates
OWM, primates, humans: 2:1:2:3
- > OWM have large canines projecting beyond level of teeth
- > diastema: gap between upper canine and incisor to accommodate lower canine so mouth can close
to allow for large upper canine: crown of first lower premolar is slanted back with sharp edge
-> upper canine fits tight and is sharpened by grinding against premolar
4 cusps upper
5 cusps lower
->evolved due to fruit diet of apes
human dentition: canines don’t project/interlock
- > more similar to incisors
- > small teeth take up less jaw space
- > thus: dental arcade evolved from u shape to parabolic
prognathism and brow ridges
non human apes and early homies have increased prognathism and brow ridge
trend: teeth size decreased so face flattened, chin developed and prominent nose
bipedalism: flatter face shirts weight to central position
to allow skull to balance when upright
frontal lobe increased: brain occupies larger volume
->cranium extends forward and brow ridge decreased
flatter face and noticeable forehead
ape like
thicker cranium bones smaller cranial capacity heavy brow ridges no/sloping forehead lower cranium less prominent cheekbones saggital crest FM post central larger prognathic jaw heavy thick mandible no chin larger teeth diastema prominent canine incisor and molar size difference narrow pelvis less wedge shaped LV wide ribcage shorter less mobile thumb long curved fingers parallel femurs arms longer
human like
thinner cranium bones larger cranial capacity reduced brow ridges vertical forehead dome cranium prominent cheekbones no crest central FM flatter face and smaller jaw slender/thinner mandible chin smaller teeth no diastema less prominent canine even teeth broader pelvis wedge shaped LV smaller ribcage longer thumb with increased opposability shorter straight fingers converging femurs arms shorter
australopithecines
from laetoli footprints: bipedal (varying gait to humans) lateral transmission of weight longitudinal arch parallel big toe
canine: short non projecting
no diastema, parabolic shape
low forehead
more projected jaw
femur, pelvis, carrying angle more human like
non opposable robust big toe
rounded skull at the back
s shaped spine= upright stance
thumb shorter and less mobile than humans
->heavier finger-> better adapted to power grip (arboreal?)
afarensis v africanus
afarensis: 430cm^3 2.8-3.9 mya east africa F= 105-110cm, M=150 cm low sloping forehead short sagittal crest for males diastema curved fingers
africanus: 457cm^3 2-3.2 mya south africa F= 110cm, M= 135cm slightly arched forehead smaller brow ridge no diastema some curvature of fingers
Paranthropus robustus
542cm^3
1.2-1.8 mya
not ancestor of humans: part of evolutionary branch with no descendants
robust jaw and skull
F=1m, M= 1.2m
large sagittal crest: for attachment of strong chewing muscles
large molars and premolars, small incisors and canines
less prognathism than australopithecines
wide dish shaped face with zygomatic arch
heavy brow ridges
homo habilis
590cm^3 1.5-2.3 mya east and South Africa compared to australopithecines: larger brain, smaller teeth->meat in diet, taller, more erect F= 110cm M= 130cm rounder skull smaller brow ridge central FM moderate prognathism parabolic jaw shot legs long arms curved finger bones: strong power grip able to form precision grip -> adept at tool making
homo erectus
1004cm^3 first humans to show modern human like body -> life on ground larger brain curve of dental arcade: shorter and rounder at front shorter compact jaw, chin beginning to form modern teeth (similar diet?) use of fire and tools 145-185cm short stocky body with thicker bones low sloping forehead defined brow ridge large thick jaw without chin decrease in molar size
homo neanderthalensis
Europe, Asia, northern Africa
side brach along pathway to modern human
1485cm^3 adapted to colder environments ->big faces - low large skulls - heavy brow ridges - slightly larger brain
back of skull drawn in to bun (occipital bun)
lacked chin
swept back cheeks: streamlined appearance
robust but larger brain
prognathism: accentuated by way nasal bone protrudes
-> larger, wider nose-> adaptation for environment
short (M=150cm) ->limbs shorter heavily jointed with powerful muscles more heavily built than humans barrels shaped chest thick neck muscles
large skull with large brain
-> extra brain capacity for control of extra muscles
Homo sapiens
Cro magnon: first anatomically modern people in Europe 40 000 to 12 000 ya member of our species - shorter skulls and higher - rounded skull - less prominent brow ridge - reduced face projection - smaller jaw - chin developed - broad and short face - eye sockets well separated large brain, hunter gatherers
1350cm^3
neanderthals v sapiens
neanderthals: 28 000 - 300 000 ya shorter more robust wider shoulders F: 156cm, M: 168cm long low brain case occipital bun thick brown ridge receding foreheads elongated skull flared zygomatic arch depression at back of skull for neck muscle attachment shorter thicker limbs with large joints large robust prognathic jaw lacking chin large teeth barrel shaped ribcage
sapiens: 300 000 to present short slender trunks long limbs F: 160 cm, M: 175cm short base high brain case short jaw bony chin Long leg with short arms straight fingers and toes less barrel shaped ribcage
culture
anything that is learnt
cultural development is important to overcome environmental challenges
cultural evolution: gradual improvement in culture, overcoming environmental and other challenges
australopithecines tools
OLDOWAN
HOME bases
no fire use evidence
pebble tools (choppers, scrapers, flakes, chisels) required precision grip 2.5mya tools marked start of cultural evolution -> allowed them to exploit more habitats
homo habilis
OLDOWAN
used oldowan tools
-> sharpened by striking one rock to another
(skinning animals, chopping meat, breaking open bones, crushing plants, digging edible plant roots)
hunter gatherers: diet consisted of plant materials, supplementing meat -> provided complex fats for brain growth
-> worked in groups with specific roles: food brought back was shared
bulge of Broca (speech production area): pressure to speak spoken language. rudimentary speech
-> larynx not capable of making complex sounds
both hunter and scavenger: shown by recovered bones with cuts made by stone tools
homo erectus
ACHEULIAN
trend: becoming more independent of environment
tools: tear drop shaped. flaked around edges to forms bi faced lumps: used as hand axes
found in France (stone and bone)
organised: logical thought and working together
more systematic tool use: increased commitment to meat eating
FIRE
mutual cooperation needed to create complex society
FIRE
kept predators away at night
warmth
light at night
used to stampede animals
important for migration during ice age
enabled cooking of food: increased food range by improving flavour and digestibility
-> made food safe to eat (destroyed parasites)
Homo neanderthalensis
MOUSTERIAN
trend: becoming more independent of environment
MOUSTERIAN: production of stone flakes trimmed to form various cutting, scraping, piercing and gouging tools
- LEVALLOIS technique: piece of stone trimmed to disc shape, struck by another stone to produce flakes that were flat on one side and had sharp edges
- > slow labour intensive, required planning and foresight (significant development of foresight)
flake tools joined to handle/spear/arrow by hafting
increased brain capacity due to increased importance of meat
flake tools enabled those living in colder climates to become good clothe makers
buried their dead: ceremonial burial, spirituality
Homo sapien
AURIGNACIAN
SOLUTREAN
MAGDALENIAN
finer baldes, projectile weapons
~40 000 modern humans moved to Europe
-> brought clothes and shelter -> helped survive winter
AURIGNACIAN: blades made by removing long, flat rectangles from the core stone, easy to handles, effective in cutting
SOLUTREAN: willow leaf, laurel leaf points.
- > made by carefully retouching blades produced from original stone core by pressure flaking
- > for aesthetics
MAGDALENIAN: bone and antler > flint and stone for tools and art
- > made by using a burin, chisel like cutter (tool used for making other tools)
- > burin: blade shaped so it had a sharp cutting point
- bone and antler and ivory cut to make orange of tools from fine needles to barbed spear points and spear throwers
trends in tool use
- increased manipulation of materials
- increased complexity of tools
- greater variety of materials being used to make tools
- improved workmanship and development of equipment needed to make tools
- increased specialisation of tools
OLDOWAN ACHEULIAN MOUSTERIAN AURIGNACIAN SOLUTREAN MAGDALENIAN
olduvai Africa. 2.6-1.7 mya.
st acheul France, 1.7-200 000
Le moustier France. 200 000- 40 000
Aurignac France. 43 000-26 000
Solutre France. 22 000- 19000
Le madeleine France. 18000-12000
