Human Evolution: A Neuropsychological Perspective

248 Pages·1997·4.077 MB·English

by  John L Bradshaw

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Sketches from a sample ofthe Gona artefacts, the oldest known tools from anywhere in
the world: a, flaked pieces; b, discoid; c, unifacial side chopper; d-f, detached pieces.
Reprinted with permission from Semaw, S., Renne, P., Harris, J.W.K. et aI., 2.S-million
year-old stone tools from Gona, Ethiopia, Nature, 1997,385,333-336. Copyright © 1997
Macmillan Magazines Ltd.
View of Jinmium rock-shelter (Northern Territory, Australia) and engraved pits
(cupules) dated to older than 58,000 years and perhaps the world's oldest parietal (rock)
art. Courtesy of Paul S.C. Ta!;on, Australian Museum.
Human Evolution
A Neuropsychological Perspective
John L. Bradshaw
Neuropsychology Research Unit, Department of Psychology,
Monash University, Clayton, Australia
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~;I~~~~~i?G~XP Press
HOVE AND NEW YORK
First published 1997 by Psychology Press Ltd
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Psychology Press is an imprint o/the Taylor & Francis Group, an informa business
© 1997 by Psychology Press Ltd
All rights reserved. No part of this book may be reprinted or reproduced
or utilized in any form or by any electronic, mechanical, or other means,
now known or hereafter invented, including photocopying and recording,
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British Library Cataloguing in Publication Data
A catalogue record for this book is available from the British Library
ISBN 13: 978-0-86377-504-8 (hbk)
ISBN 13: 978-0-86377-505-5 (Pbk)
ISBN 10: 0--86377-504-7 (hbk)
ISBN 10: 0--86377-505-5 (Pbk)
Typeset by DP Photosetting, Aylesbury, Bucks
Contents
Preface viii
Preamble x
1. Evolution to the advent of the mammals 1
Formation of the Universe and the Earth 1
Appearance of life 2
The Cambrian explosion of diverse life forms 9
The first chordates and vertebrates 10
The first tetrapods 13
The earliest mammals 15
Summary and conclusions 19
Further readings 19
2. Primates to hominids and the advent of bipedalism 21
The Primates 21
The hominoids 22
The hominid lineage 24
The advent of bipedalism 26
Obstetrics and the pelvis 32
Summary and conclusions 34
Further readings 35
3. Evolution of the genus Homo 37
Homo habilis 37
Homo erectus 40
v
vi BRADSHAW
Archaic Homo sapiens and the Neanderthals 44
The morphology and origin of anatomically modem
Homo sapiens sapiens 48
Evidence from molecular biology 50
Migration and expansion 56
Summary and conclusions 56
Further readings 57
4. Art, culture, and prehistory 59
The art and culture of the Mousterian and Acheulian 59
The art of the European Upper Palaeolithic 66
The psychology of art, ancient and recent 71
Summary and conclusions 74
Further readings 75
5. Language and communication 77
The coevolution of genotype and language 77
The prehistory of spoken language 79
Language, speech, and communication 81
(How) did language evolve? 83
Critical periods and speech perception 87
Categorical perception 89
Categorization in nonhuman communication 91
Language mediation by a distributed network 91
Apes and language 93
A view of language evolution 99
Gesture and language 101
Summary and conclusions 102
Further readings 103
6. The central and peripheral realization of speech 105
Speech and articulation 105
The supralaryngeal vocal tract in apes and humans 107
The supralaryngeal tract in apes and neanderthals 109
Did Homo habilis possess speech-related areas in the brain? III
Speech-related areas and aphasia in Homo sapiens sapiens 111
Category specificity and semantic representation 117
Neuroimaging and speech localization 118
Summary and conclusions 119
Further readings 120
7. Tool use and praxis 123
Hands and tools 123
Nonhuman tool use 125
Hominid tool use 129
Movement, the frontal-basal ganglia circuits, and praxis 133
1. CONTENTS vii
Apraxia: the loss of the ability to use tools 138
Praxis, tool use, and language evolution: is a synthesis possible? 140
Summary and conclusions 142
Further readings 143
8. Encephalization and the growth of the brain 145
The allometric ratio 145
The growth of encephalization in the fossil record 146
Laminar and columnar organization in the cortex 147
Neurogenesis and brain-body growth and development 147
Plastic reorganization in the adult brain 151
Whole-object recognition and "binding" 152
Brain size and intellectual capacity 153
Summary and conclusions 154
Further readings 155
9. Intelligence, social intelligence, consciousness, and self-awareness 157
The evolution of intelligence 157
The theory of Machiavellian intelligence 163
Self-recognition in mirrors and self-awareness 170
Consciousness 173
Summary and conclusions 178
Further readings 179
10. An overview 181
Postscript 197
References 199
Author index 221
Subject index 232
Preface
Like many children, I was fascinated by fossils. In my case it stemmed from
a holiday, when 11 years of age, on a coastline (why are all childhood
vacations spent by the sea?) where there were dramatic exposures of the
Jurassic Blue Lias (dialect for "layers", but now a geological division
recognized world-wide and corresponding to the apogee, if that term is
appropriate, of the dinosaurs). I never found a dinosaur, though I did
eventually discover a "worteberry" (vertebra), and many pretty and
aesthetically appealing ammonites and other fossils. I still have them.
At school, and for a while at university, I studied the classical languages,
Latin and Greek, with a little Sanskrit (the Indo-side ofIndo-European, the
putative and reconstructed ancestor of many of the languages of Europe and
parts of Asia). Languages do not strictly fossilize, but we can find something
akin to a fossil in many everyday words. For instance, the words for "dog"
(hound in English, hund in German, can- in Latin gwn in Welsh, kun- in
Greek) can take us on a fascinating journey through place and time. It is a
game anyone who knows the elements of a few reasonably disparate
languages can play.
As a university student I spent exciting weeks, with wonderful Welsh
characters who possessed such evocative names as Mervyn Bevan-Evans
and Trevor Pennant-Williams, scientifically excavating Iron-Age hillforts
and Bronze-Age burials. We did not find (nor were we looking for) gold,
and the work was often hard and uncomfortable. The rewards were the open
moorland air and a few more pebbles in the mosaic of archaeological
viii
PREFACE ix
knowledge. I have since enjoyed amateur participation in "digs" in the
Middle East and Oceania, to say nothing about photographing the mag
nificent aboriginal Rock Art, including the Kimberley "Bradshaw paint
ings", of Australia.
As a neuroscientist with a number of dedicated graduate students and
colleagues, I have spent a fulfilling career studying the mechanisms, and
clinical breakdown, of attention, movement, language, motor skill and
praxis, object and pattern recognition. We have been fortunate in our access
to many otherwise unfortunate but generous individuals with such disorders
as focal brain lesions, Parkinson's, Huntington's, and Alzheimer's disease,
Tourette's syndrome, schizophrenia, autism, and so on. From controlled
experiments and the willing participation of such individuals we have
learned much about how the brain mediates speech, language, thought,
praxis, and conscious self-awareness.
In recent years there have been a number of books about human evo
lution. These have tended either to view it from the author's own personal
experiences in often ground-breaking archaeological exploration and dis
covery, or to concentrate upon a particular aspect (the evolution of lan
guage, or of social intelligence, or of consciousness), or to elaborate a
particular theoretical viewpoint. In the last respect, this book certainly
subscribes to the view that all our cherished human attributes, so far from
being unique, are grounded in our primate evolutionary history. Otherwise,
however, it seeks to provide a comprehensive and fully referenced account,
from the neuropsychological, molecular, anthropological, primatological,
archaeological and palaeontological evidence, of what we are and how we
have got here. Of course, it cannot be the last word on the matter; weekly,
new finds in all these fields require reassessment and modification of the
current picture. Unfortunately, in such a domain of interest, a book can
never be wholly up to date. However, I hope my professional knowledge of
one relevant area, and an amateur (and I hope not too uninformed)
understanding of the others, will permit the painting of a picture not too
unrepresentative of what may have happened.
I would like to express my profound gratitude to everyone who provided
me so readily with illustrative material, often of their very latest finds, to
Rosemary Williams, who provided the artwork often at short notice, and
finally to my wife and colleague Judy, who typed and produced the
manuscript.