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

◦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 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 Footprints  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 24 Dated to ~ 1.8mya