hominin evolution
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Hominin Evolution
Pre-dating Australopithecus Hominins discovered in north-central and eastern Africa
Bipedal – debatable in some species
We will focus on the species for which there is ‘stronger’ evidence of bipedalism
Ardipithecus ramidus Middle Awash area of Ethiopia Approximately 4.4mya
Found: ◦ Dental◦ Cranial◦ Post-cranial remains
Ardipithecus ramidus
Indicators of Bipedalism◦ Foramen magnum location
◦ Femur and pelvis
◦ Humerus – chimp features, but not weight bearing
◦ Foot Phalanges – curved like apes
Ardipithecus ramidus
Ardipithecus ramidus
◦Ardi = “facultative” biped◦ What do you think this term mean?
Living in both worlds: up in the trees at times while also on the ground
Australopithecus afarensis
East Africa◦ Hadar, Ethiopia◦ Laetoli, Tanzania
3.6-3.0 mya
Forest, woodland, grassland
A. afarensis – Traits
Bipedal◦ Vertical foramen magnum◦ Heel-knee joint human-like
Some Arboreal Abilities Retained◦ Curved phalanges◦ Long arms for body size
Type Fossil – “Lucy” Found: 1974, Hadar, Ethiopia
40% complete skeleton◦ Both arms◦ Much of the pelvis◦ Left femur, right tibia◦ Hand and Foot bones
Adult (based on 3rd molar)◦ Female?
Type Site: Laetoli Type Site: Laetoli FootprintsFootprints
Tanzania
3.6 mya
75 feet long preserved Walked over volcanic
ash, rained, hardened
3 hominins: 2 adults, 1 child
A New Hominin Australopithecus sediba
◦ Discovered in 2008; located in South Africa
◦ Proposed by some to be the best candidate ancestor for the genus Homo
A New Hominin◦ Features:
◦ Small brain◦ Pelvis – mixture of
Australopithecus-like and Homo-like features
◦ Hand – combination of ape- & human-like
◦ Foot & ankle shape – combination of ape- & human-like
The Genus Homo – Overall Trends
Characterized by:◦ Increased brain size◦ Increased body size◦ Diet expands
◦ Meat incorporation◦ Reliance on material culture:
◦ Stone tool use◦ Fire and cooking
Introduction To Homo habilis
Contemporaneous with australopithecine remains
Anatomically different than specimens assigned to the genus Australopithecus
Distinguishing feature – cranial size◦ H. habilis shows an increase in cranial size as compared to
Australopithecines
Homo habilis – OH 24
Location: Olduvia Gorge
Comparison to Australopithecines:◦ Larger brain ◦ Less protruding face
“Twiggy” or OH 24Dated to ~ 1.8mya
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