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