Chp 13 Hominin Evolution - Human Bio

What are the two different types of Australopithecines (southern apes) ?

1. Gracile

→ A afarensis, A. Africanus

2. Robust

→ A. robustus, A. boisei

What are the anatomical features in the cranial capacity of Australopithecines?

Cranial Capacity:

• 450-550 cc, average 480cc (similar to gorilla)

• Brain more like humans relative size to body between chimps & modern humans

What are the anatomical features in the brow ridge of Australopithecines?

• brow ridge present

What are the anatomical features in the foramen magnum of Australopithecines?

• more forward than apes, mid/rear

What are the anatomical features in the skull of Australopithecines?

• rounded @ back

What are the anatomical features in the teeth of Australopithecines?

• canines short & non-projecting= resemble incisors

• → tgt make cutting teeth

• Diastema present in some

• Parabolic shape

What are the anatomical features in the foot of Australopithecines?

• non-opposable thumb

• Strongly built big toe

What are the anatomical features in the Hand of Australopithecines?

• thumb shorter & less mobile than humans

• Heavily built fingers

• Features adapted for precision & power grip

What are the anatomical features in the vertebral column of Australopithecines?

• curved

What are the anatomical features in the femur of Australopithecines?

• angled

• → so foot under centre of gravity

What are the anatomical features in the height of Australopithecines?

• 100-150cm

Compare Gracile Australopithecus against RObust Australopithecus

Height:

• Gracile: 120-140cm

• Robust: ~30cm taller

Weight:

• Gracile; 25-30kg

• Robust: ~40kg heavier

Teeth:

• Gracile: teeth more in proportion

• Robust: large broad molars & small sharp incisors & canines

Jaw

• Gracile: smaller jaw muscles

• Robust: powerful chewing muscles

What is the Australopithecus afarensis primate?

• small, gracile, small-brained, bipedal

• Skull similar to chimpanzee

• More human-like teeth

• Human0like pelvis

• Leg bones confirm bipedal

What are some features of the Australopithecus afarensis?

• Important specimen: Lucy?

• Known date: 3,9-2.9 mya

• Brain size: 430cc

• Height: 105-110cm (f) ~150cm (m)

• Physique: light build, relatively long arms, curved inters & toes, sexual dimorphism

• Skull shape: ape like face, low-sloping forehead, prominent brow ridge, flat nose, no chin, little skull behind foramen magnum, large dish-shape face

• Teeth & jaws: human-like teeth, canines smaller than apes (larger than humans), diastema present, Jae shape ½ human & ape

What were the Australopithecus Africanus primates?

• also small, gracile, bipedal, but slightly larger than afarensis

• Generally considered to be specific to South Africa

• Differs from early Australopithecines in East Africa by having larger back teeth & smaller Cannes

• Jae shape fully human-like

What are some features of the Australopithecus Africanus?

• Important specimens: Taung child?

• Known date: ~3.3-2.1 mya

• Brain size: 480cc

• Physique: light build, prob? Long arms, more ‘human’ features, less sexual dimorphism than A.afarensis

• Skull shape: brow ridge less prominent, higher forehead, shorter face, no sagital crest, low facial angle

• Teeth & jaws: much larger than humans, shape of jaw fully parabolic as humans, canine teeth further reduced

What are some general features of Paranthropus robustus (besides humans) ?

• Time: ~1.8-1.2 Mya

• Height: 1.2m (M) 1m (F)

• Weight: 54kg (M) 40kg (F)

• Cranial capacity: ~520cm³

What other more distinctive features do Paranthropus robustus (besides humans) have?

Tough grases needed adaptations

• vv large megadont cheek teeth w thick enamel

• Large flared zygomatic arches allowed for large chewing muscles

• Large Sagittarius crest = provide large area to anchor chewing muscles to skull

What is the timeline of the genus Homo?

What are some of the features of the skull, teeth & jaw of Homo habilis?

• bigger brain (610cc)

• Rounded cranium w no sagital crest

• Bulge in Broca’s area of brain for speech production

• Prominent brow ridge

• Smaller, narrower face than Australopithecines

• Flat nose

• Projecting jaw (prognathism_

• More skull behind for men magnum

• Jaw less massive compare w Australopithecines

• Tooth raw display modern curve w narrow molars

What are some General features of Homo erectus?

Live: 1.89 - 110,000 Mya

• originate in Africa (first human to venture out to Africa??)

• Species dispersed quickly, moving through African tropics, Europe, South Asia, Southeast Asia

Cranial Capacity: ~1050cm³

• forehead vvv receded

• Vv prominent eyebrow ridges

• Vv flat, broad nose

• Legs longer than arms

Height: 145-185cm

Weight: 40-68kg

What are some more specialised features of Homo erectus?

• Curve of dental arcade shorter & more rounded in front

• Jaw shorter & more compact

• Chin beginning to form

• Teeth larger than modern humans but smaller than earlier species

  • → Particularly Smaller molars = indicate change in diet to softe food, greater amt of meat, & eventually cooked food

• Occipital lobe = enlarge cerebellum (visual processing center)

• Big toe parallel to other toes & other toes short

• Footprints show pronounced human-like arch

• Long, flattened cranium

• Shelving forehead

• Flat face

• Projecting jaw (prognathism)

What are some general features of Homo Neanderthalensis?

• Exist 400,000 - 40,000 years ago

• Average cranial capacity: 1500cc, additional capacity required for control of extra muscles

• Male 78kg, female 66kg

• Short cold-adapted bodies (1.5-1.7m), w thick & heavy bones

• Large skulls & heavy brow ridges

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What are some key distinctive features of Homo neanderthalensis?

• larger wider nose (adaptation for life in cold dry environments)

• → humidifying & warming cold air

• Back of skull had bum shape (house larger cerebellum for control of large skeletal muscles)

• Chin appearing, more prognathism, nasal bones project forward

• Barrel shape chest

• Tick neck muscles

• Bodies short & stockier than unmans

• Heavy joints in limbs to support weight

• Create small SA:VOL adaptation to living in cold enviro