Copyright © 2013 Pearson Education, Inc. All rights reserved. Exploring Biological Anthropology: The Essentials, 3 rd Edition CRAIG STANFORD JOHN S. ALLEN SUSAN C. ANTÓN

Copyright © 2013 Pearson Education, Inc. All rights reserved. Chapter 10 Early Hominins and Australopithecus

Copyright © 2013 Pearson Education, Inc. All rights reserved. Becoming a Biped Anatomical Changes – balancing the body’s weight over two limbs Constructing the Bipedal Body Plan Why Bipeds?

Copyright © 2013 Pearson Education, Inc. All rights reserved. The Transition to Human Behavior What Made Humans Human? – the anatomical shift from quadrupedalism came after a behavioral shift began – at every stage of the process, natural selection favored the form the evolving protohominin took – at the earliest stages of hominin evolution, brain size and intelligence were quite apelike

Copyright © 2013 Pearson Education, Inc. All rights reserved. Will you Know a Hominin When You See One? Bipedality Dentition – Parabolic arch – Size of anterior and posterior teeth – Prognathism – CP 3 – Enamel Cranial Features

Copyright © 2013 Pearson Education, Inc. All rights reserved. The First Hominins Sahelanthropus tchadensis ( MYA) – Chad – 6-7 mya – Less prognathic face – Large brow-ridge – Smaller canines – Anterior foramen magnum – Small brain – U-shaped arcade – Thin enamel

Copyright © 2013 Pearson Education, Inc. All rights reserved. The First Hominins (cont’d) Orrorin Tugenensis (6.0 MYA) – Kenya – 6 mya – Arm and femoral fragments may suggest bipedalism – Thick enamel – Small teeth – Large upper canines

Copyright © 2013 Pearson Education, Inc. All rights reserved. The First Hominins (cont’d) ramidus 4.4 mya Smaller canine Anterior foramen magnum Apelike molars kadabba mya More apelike dentition Originally considered a variant of ramidus Ardipithecus ramidus (4.4 MYA) and Ardipithecus kadabba ( MYA)

Copyright © 2013 Pearson Education, Inc. All rights reserved. Australopithecus and Kin Australopithecus anamensis ( MYA) – Thickened tibia – Primitive dentition – Lumped with afarensis? – Lived in forested region

Copyright © 2013 Pearson Education, Inc. All rights reserved. Australopithecus and Kin (cont’d) Australopithecus afarensis – mya – Lucy – Short, broad pelvis – Tilted femurs – In-line big toe – Sagittal crest – Small brain – Sexually dimorphic

Copyright © 2013 Pearson Education, Inc. All rights reserved. Australopithecus and Kin (cont’d) Australopithecus bahrelghazali ( MYA) – Western Africa – Mandible fragment with seven teeth – A specimen of afarensis?

Copyright © 2013 Pearson Education, Inc. All rights reserved. Australopithecus and Kin (cont’d) Kenyanthropus platyops (3.5 MYA) – Flat face – Small molar teeth – afarensis?

Copyright © 2013 Pearson Education, Inc. All rights reserved. Australopithecus and Kin (cont’d) Australopithecus garhi (2.5 MYA) – Small brain – Prognathic face – Large canines – Sagittal crest – More human-like postcranial proportions? – Tool use?

Copyright © 2013 Pearson Education, Inc. All rights reserved. Australopithecus and Kin (cont’d) Australopithecus africanus (3.5-<2.0 MYA) – Slight brain increase – Rounded vault – No crests – Less projecting face – Bipedal postcranial anatomy

Copyright © 2013 Pearson Education, Inc. All rights reserved. Australopithecus and Kin (cont’d) Australopithecus sediba ( MYA) – Discovered 2010 in South Africa – Slight brain increase ( cc) – Characteristics similar to Homo dental anatomy derived face features of the pelvis

Copyright © 2013 Pearson Education, Inc. All rights reserved. Australopithecus and Kin (cont’d) 'Robust' Australopithecus (or Paranthropus) – Hard object feeding Sagittal crest Large cheek teeth Flared zygomatic arch Dished face Extreme postorbital construction – Woodland and open woodland habitat

Copyright © 2013 Pearson Education, Inc. All rights reserved. Australopithecus and Kin (cont’d) Robust Australopithecines (cont’d) Australopithecus (p.) aethiopicus – mya Australopithecus (p.) boisei – mya Australopithecus (p.) robustus – mya

Copyright © 2013 Pearson Education, Inc. All rights reserved. Understanding the Australopithecine Radiation Cohabitation Tools and Intelligence Ancestors and Descendants