Table Of ContentContributors
DICK M. BADOUX
JOHN V. BASMAJIAN
MATT CARTMILL
RICHARD LEE DECKER
J. P. GASC
FARISH A. JENKINS, JR.
F. K. JOUFFROY
O. J. LEWIS
DAVID ROBERTS
M. D. ROSE
FREDERICK S. SZALAY
RUSSELL H. TUTTLE
ALAN WALKER
PRIMATE LOCOMOTION
Edited by
FARISH A. JENKINS, JR.
Department of Biology and
The Museum of Comparative Zoology
Harvard University
Cambridge, Massachusetts
A C A D E M IC PRESS New York and London 1974
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list of Contributors
Numbers in parentheses indicate the pages on which the authors' contributions begin.
DICK M. BADOUX (1), Institute of Veterinary Anatomy, State University
of Utrecht, Utrecht, Holland
JOHN V. BASMAJIAN (293), Departments of Anatomy, Physical Medicine,
and Psychiatry, Emory University, Atlanta, Georgia
MATT CARTMILL (45), Departments of Anatomy and Anthropology, Duke
University, Durham, North Carolina
RICHARD LEE DECKER (223, 261), Department of Anthropology, Hunter
College, New York, New York
J. P. GASC (117), Laboratoire de Biologie-Vertébré, Université Paris XI,
Paris, France
FARISH A. JENKINS, JR. (85), Department of Biology and The Museum of
Comparative Zoology, Harvard University, Cambridge, Massachusetts
F. K. JOUFFROY (117), Centre National de la Recherche Scientifique,
Paris, France
O. J. LEWIS (143), Department of Anatomy, St. Bartholomew's Hospital
Medical College, Charterhouse Square, London, England
DAVID ROBERTS* (171), Peabody Museum of Natural History, Yale Uni
versity, New Haven, Connecticut
M. D. ROSE (201), Department of Human Anatomy, University of Nai
robi, Nairobi, Kenya
* Present address: The School of Medicine and The School of Dental Medicine,
University of Pennsylvania, Philadelphia, Pennsylvania.
ix
χ LIST OF CONTRIBUTORS
FREDERICK S. SZALAY (223, 261), Department of Anthropology, Hunter
College, and Department of Vertebrate Paleontology, The American
Museum of Natural History, New York, New York
RUSSELL H. TUTTLE (293), Department of Anthropology and Committee
on Evolutionary Biology, and the Biology Collegiate Division, Univer
sity of Chicago, Chicago, Illinois; and Yerkes Regional Primate Re
search Center, Emory University, Atlanta, Georgia
ALAN WALKER (349), Department of Human Anatomy, University of
Nairobi, Nairobi, Kenya
Preface
This book reviews aspects of current work on primate locomotion, and
was assembled in an attempt to bring together selected approaches and
topics in this field of study which are highly diverse but which at the same
time offer important insights into traditional disciplines—anatomy, an
thropology, paleontology, and zoology. Therefore, the book is intended
not only for researchers dealing with primate locomotion, but equally for
students and others who share an interest in mammals and locomotor
adaptations.
The first major studies of primate locomotion were based on field ob
servations and emphasized classifications, or so-called locomotor cate
gories, which grouped primate species according to major behavioral and
anatomic similarities. However, the concept of "primate locomotion" as a
subject of study is now rapidly changing. Although locomotor classifica
tions are still useful as a conceptual framework, current workers are ex
ploring new techniques and concepts that distinguish behavioral and
anatomic differences among primate species that traditionally have been
assigned to the same locomotor category. The contributors to this book
describe in detail some of these new trends as well as provide guidance
to areas in which further investigation might be particularly productive.
Biomechanical principles, which are at the foundation of our understand
ing of locomotor adaptations, are outlined by Badoux in the first chapter.
The critical importance of understanding primate locomotion in terms of
habitat and naturalistic behavior is emphasized in papers by Rose and
Walker, whereas the chapters by Tuttle and Basmajian, Jenkins, and
Jouffroy and Gasc discuss data from instrumentation presently restricted
to laboratory settings. Paleontology brings an increasingly greater perspec
tive to our view of primate adaptations as the chapters by Szalay, Decker,
and Walker show. Furthermore, the degree to which paleontological and
neontological interpretations may be closely interrelated is repeatedly
demonstrated in discussions by Cartmill, Lewis, Tuttle and Basmajian,
and others. The anatomy of various aspects of the appendicular musculo-
xi
xii PREFACE
skeletal system, still a major basis for comparative study of primate
locomotion, is the subject of different styles of functional analysis in
reviews by Cartmill, Lewis, and Roberts.
If a single conclusion may be drawn on the basis of these diverse
studies, it is that different approaches and techniques are essential to
understand the complex phenomena of primate locomotion. Furthermore,
the need for further field studies is clearly presaged; the wealth of
detailed information derived from captive specimens and experimental
situations must be reexamined in the context of each species' natural
habitat and behavior. Thus, primate locomotion continues to offer a
spectrum of biological problems to challenge both field and laboratory
research.
To the staff of Academic Press I am grateful for assistance in every
phase of this undertaking. Special recognition is due Professor Charles R.
Noback, my friend and former colleague in The Department of Anatomy
at The College of Physicians and Surgeons of Columbia University, with
whom the concept of this book was initially conceived.
FARISH A. JENKINS, JR.
1
An Introduction to Biomechanical
Principles in Primate Locomotion and Structure
DICK M. BADOUX
General Principles
At the present time, a detailed survey of primate biomechanics cannot
be made since not enough is known about the various forms of locomotion
in primates, in general, and their joint movements, in particular; detailed
biomechanical information on specific parts of the locomotor apparatus of
nonhuman primates is scarce. However, the present contribution is based
upon the supposition that biomechanical principles based on mammalian
morphology and locomotion in general apply also to primates. Since my
principal field of interest lies in the analysis of parallels and analogs
between mammalian and mechanical structures, some of the ideas ex
pressed in this chapter will be personal and perhaps provocative.
Biomechanics is an old science and its practical implications date as far
back as man's dawn as a toolmaker; however, it obtained its firm theoret
ical basis from technical advances made principally in the last three
decades. Generally speaking, biomechanics deals with forces, accelera
tions, and movements acting in and on living bodies, the analysis of which
is made possible by a wide variety of specialized and sophisticated tech
niques. Since living matter is subjected to the same physical laws and
rules as inanimate bodies, the subdivision of biomechanics is analogous
to that in physical mechanics and distinguishes two subdisciplines:
"biodynamics" and "biostatics." Biodynamics is subdivided into "kine
matics" and "kinetics." Kinematics analyzes motion in space and time
1
2 Dick M. Badoux
without taking into consideration the forces which cause these motions.
Kinetics studies changes in motion caused by an unbalanced system of
forces and determines the force required to produce any desired change
of motion.
Despite the great variation in primate conformation and the versatility
of their movements, the basic mechanical principles underlying primate
locomotion are relatively limited and derive from Newton's three laws of
motion. The first law states that a body continues in its state of rest or
uniform motion in a straight line except insofar as it is compelled by
applied forces to change that state. Although the first part of the law with
regard to bodies at rest is self-evident, the second part needs further con
sideration. Consider a monkey jumping from one branch to another. The
body leaves the branch with a velocity of V m/sec and would perpetually
continue its course in a straight line if there were no gravitation and air
resistance. Under the influence of gravitation and air resistance it follows
a parabolic curve and comes to rest on the "target" branch. The second
law states that change of momentum per unit time is proportional to the
applied force and takes place in the direction of the force. The biological
implication is that when an animal exerts a propulsive force F ( expressed
in newtons), the velocity V (in meters) imparted to the animal is
proportional to the magnitude of the force and the period of time Τ (in
seconds) during which it acts and is inversely proportional to the mass
M (in kilograms) of the body: hence
V = FT/M (1)
The velocity of the body is increased by the amount F/M for every second
for which the force is applied so that the acceleration A (in meters per
second per second ) is :
A = F/M (2)
If an animal suddenly comes to rest under the influence of a constant
restraining force F ( friction between the ground and the soles of the hands
and feet of the fixed legs), the whole of the animal's kinetic energy is
dissipated when the force moves the animal distance S ( in meters ) so that
FS = \ MW2 (3)
or
S = MV2/2F (4)
The negative acceleration follows from Eqs. (2) and (4) :
F = MA
1. INTRODUCTION ΤΟ BIOMECHANICAL PRINCIPLES 3
hence
S = MV2/2MA = V2/2A
thus
A = V2/2S (5)
The third law states that forces always occur in pairs, each pair consist
ing of two equal opposites; in other words, for every action there must be
a reaction. The implication of this well-known principle is the most
important concept in the analysis of animal locomotion: when an animal
subjects its body to a forward propulsive force, the environment exerts an
equal but opposite background force against the animal. The animal
moves forward because the environment resists the movements of the
limbs relative to the body.
"Biostatics" deals with forces and their equilibrium acting upon animals
and their organs in a state of rest or in motion at uniform velocity in a
straight line; it draws upon analogies between the components of the
locomotor apparatus—bones, cartilage, muscles, ligaments—and mechan
ical structures. Furthermore, biostatics includes the study of load effects
on locomotor organs and their individual members and is closely related
to the subject of "material strength." Biostatic investigations therefore
cover such subjects as strength of bone and cartilage, shape and position
of trabeculae in spongy bone, lubrication and wear in joints, and many
others. The most common concepts in this type of biomechanical research
are "stress" and "strain." A stress is constituted by the equal and opposite
action and reaction which take place between two bodies or two parts of
the same body transmitting forces. A simple example of material subjected
to stress is that of a tendon attached to a bone (Fig. 1). Let the force
exerted by the muscle be F kg. Consider a planar section XX through the
tendon perpendicular to its axis, with an area measuring Ρ cm2 and divid
ing the tendon into the portions A and B. The portion A exerts a longi
tudinal pull on Β and vice versa. The average force per cm2 at the section
XX is
cr = F/P (6)
t
and this is the mean intensity of "tensile stress" at the section. If the angle
of insertion of the tendon be a, then Fi = F cos a is the component of F
acting perpendicularly to the axis of the bone. At the point of insertion of
the tendon, consider a planar section YY of Ρ cm2 perpendicular to the
long axis of the bone, and dividing the bone into the portions C and D.
The force Fi has the tendency to slide C to the right side relative to Ό
