Towards Man (Hominins)



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Towards Man (Hominins)





  • Sahelanthropus tchadensis 6 to 7 m.y.a.

    • brain & skull chimp-like but thicker brow ridges and face flatter

    • Smaller canine teeth than chimp

    • Neck muscle attachment and foramen magnum position hint upright walking

  • Orrorin tugenensis 6 m.y.a. Very few fossils, may be bipedal related to Ardipithecus

  • Ardipithecus ramidus In the Afar language Ardi means "ground". 'Ramid' means 'root‘. Pithecus = ape

  • 4 – 6 m.y.a. (“Ardi” 4.4 m.y.a.)

  • About 120 cm tall and 50 kg.

  • Ape-like upright walker – suggested by toe structure.

  • Feet well adapted to grasping, (big toe not in line with others) and able to climb trees. The structure of Ardi's feet, pelvis, legs and hands suggest that she was a biped on the ground, but a quadruped in the trees. Did NOT knuckle walk.

  • Chimp sized brain.

  • Teeth resemble modern human teeth more closely than they do those of a chimpanzee.

  • Lived in woodland conditions.

  • Australopithecines (“southern ape”)

Appeared over 4 m.y.a.

Fully bipedal, short broad hip, valgus angle of knee, arched foot, forward-directed big toe. Foramen magnum nearly central.

Hip girdle not as advanced as modern human – gait not as efficient.

Shoulder ape-like, finger & toe bones curved as in apes, long arms – probably arboreal?



  • Australopithecus anamensis 4 m.y.a.
Gracile Australopthecines (Small – bodied)



Australopithecus afarensis
Australopithecus africanus

Age m.y.a.

Distribution

Cranial Capacity

Height


Mass

Build
Skull


Teeth & Jaw

4.0 – 3.0

East Africa

380 – 450 cubic centimetres (cc)

1.1 – 1.7 m

33 – 68 kg

Light, some ape-like features. Sexual dimorphism

Ape-like face, low forehead, brow ridge, flat nose.

Human-like teeth, canines bigger – diastema. Thick enamel, Jaw shape horse shoe shaped



3.0 – 2.5

South Africa

430 – 520 cc

1.1 – 1.4 m

30 – 60 kg

Light, less sexual dimorphism.


Less brow ridge, higher forehead, shorter face

Teeth & jaw larger than human but canines small. Jaw more human shaped (parabola)





Robust “Australopthecines” (larger solid – bodied)

Paranthropus aethiopicus 2.5 m.y.a. – like P. boisei (below)






Paranthropus robustus
Paranthropus boisei

Age m.y.a.

Distribution

Cranial Capacity

Height


Mass

Build
Skull


Teeth & Jaw

2 – 3

South Africa

450 – 550 cc

1.1 – 1.3 m

40 – 80 kg

Heavy, long arms, moderate sexual dimorphism

Long, broad, flat face. Sagittal crest brow ridges

Very thick jaw. Small incisors & canines. Large molar – like premolars, very large molars.



2.4 –1.2

East Africa

500 – 530 cc

1.2 – 1.4 m

40 – 80 kg

Very heavy, long arms, marked sexual dimorphism



Similar but more robust
Similar.

Homo rudolfensis & H. habilis (Handy man)


Period:

H.r. (2.5 –1.6 m.y.a.). H.h. (2.1-1.5 m.y.a.)

Brain size:

550 – 750 cc ( H.r. Higher end of the range)

Tool Culture:

Oldowan (“pebble tools”)

Distribution:

East & South Africa

Skull:

More rounded, bigger brain, smaller, narrower, longer face, narrower back teeth than A. afarensis (H.r.’s bigger). Thinner skull than later hominids. Brain may have been adapted for speech but throat not.

Post Cranial skeleton:

  • Similar to A. afarensis – long arms, curved hand bones (partly arboreal?)

  • Height 1 – 1.5 m range from small to robust.

  • Sexual dimorphism?

  • Pelvis better adapted to bipedalism.

Culture:

  • Hunter/gatherer/scavenger

  • Ate a range of animals, fish , plants (H.r. More vegetarian. H.h. omnivore. )

  • Oldowan tools made from round lava rocks, one end chipped. Flakes also used.

  • Lived in bands, had home base.

Selection Pressures

Grew bigger brains, better communication, more cooperation. Young born immature to solve problem of smaller pelvis.


Homo erectus/ergaster (Erectus is Asian = Java man & Peking man)


Period:

1.7million to 200 000 years ago Early & African, type = H. ergaster 1.8 m.y.a.

Brain size:

850 – 1250 cc (average 900 cc)

Tool Culture:

Acheulian

Distribution:

Asia, Java, Europe, Middle East

Skull:

  • Flat, thick. Sagittal keel and large brow ridge.

  • Protruding (prognathic) jaw. No chin.

  • Speech areas present in brain.

  • Teeth smaller than habilis.

Post Cranial skeleton:

  • Very like modern human but more heavily built

  • Height 1.5 – 1.8 m

Culture:

  • Acheulian stone tools. E.g. large, teardrop shaped axe. Struck from a boulder then reworked all over.

  • Scalped skulls found suggest cannibalism.

  • First to use fire – advantages: warmth, extends day for toolmaking, scares away animals at night or drives them into bogs or over cliffs for hunting, hardens points of wooden spears, improves taste, digestion and hygiene when used to cook food, promotes socialisation.

  • Made stick and stone shelters.

  • First hominid to leave Africa.

Selection Pressures

  • Bigger brain – language?

  • Manual dexterity

  • Better bipedalism

  • More cooperation.


Speech in Humans
Speech is possible in humans because of adaptations to the throat and brain. Between 18 months to 14 years of age the human pharynx grows longer than in other mammals. Its muscles are able to vary its diameter to produce a greater range of sounds. Our tongue is thicker and goes further back and allows more vowel sounds to be made.
In the brain, Broca’s area helps string sounds into words. Wernike’s area analyses incoming sounds. Some researchers believe they can detect impressions of these areas in early hominid craniums

Broca’s area Wernike’s area




Homo floresiensis (95 000 – 13 000 years ago)

Discovered recently on Indonesian island of Flores. Have been nick-named “Hobbits”



  • Small (I m, 25 kg), brain 380cc (chimp size). More like H. erectus than us – thick brow ridges, sloping forehead, no chin. Used fire and complex stone tools


Archaic Homo sapiens = H. heidelbergensis


Period:

400 000 – 100 000 years ago

Brain size:

1100 – 1430 cc

Tool Culture:

Acheulian

Distribution:

Africa, Asia, Europe, Middle East

Skull:

  • Heavy,

  • big brow ridges,

  • sloping forehead,

  • powerful jaws,

  • face less protruding.

  • Teeth similar to modern man but arcade horseshoe shaped.

Post Cranial skeleton:

  • Human – robust

Culture:

  • Similar to H erectus

Selection Pressures


Homo neanderthalensis (Neanderthal man)


Period:

200 000 – 30 000 years ago

Brain size:

1200 – 1750 cc (average 1500 cc)

Tool Culture:

Mousterian

Distribution:

Europe to Western Asia

Skull:

  • Long and low,

  • heavy brow ridges,

  • large cranial capacity,

  • large face & nose, no chin,

  • “occipital bun” at rear.

  • Teeth smaller than H. erectus.

Post Cranial skeleton:

  • Stocky and robust.

  • Strong bones, short, heavy limbs.

  • Femur curved.

  • Heavily muscled.

  • 1.5 – 1.7 m tall.

  • Body like Eskimo to conserve heat.

Culture:

  • Lived through ice ages. Often found in South-facing caves or shelters built of wood, tusks or skins. Used fur clothing.

  • Wide range of stone tools including spear points (spears were for thrusting not throwing) and bolas.

  • Good hunters – drove herds of animals off cliffs.

  • May have buried dead in foetal position, on side, knees up to chest, placed ochre, flowers and bones (food?) and horns in graves.

  • Took care of aged and crippled individuals.

  • Cannibalism evident at some sites.

  • Had vocal mechanism like ours – communicated well?

Selection Pressures

  • Related to ice age climate – became adapted to extreme environment.

What became of them?

  • Several theories exist.

  • Killed by modern humans

  • Interbred with humans (recent research shows all modern humans except Africans have a small % of Neanderthal DNA)

  • Lost competition with modern humans.



Homo sapiens (modern man)


Period:

100 000 years ago until present

Brain size:

Wide range. Average 1350 cc

Tool Culture:

Upper Paleolithic – flint tools

Distribution:

Global

Skull:

  • Bones lighter

  • Higher forehead

  • Brow ridges much reduced or absent

  • No occipital bun

  • Prominent chin

  • Jaws and teeth smaller

  • Face smaller and flatter

Post Cranial skeleton:

  • Taller but less robust than Neanderthals

Culture:

  • Stone tools finely made became more sophisticated and took longer to make using more blows.

  • Used more materials, stone, bone, antler, ivory, wood

  • Leather thongs, glues of gum and resin were used to make composite tools

  • Needles and hooks


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