Bipedalism: are we humans meant to walk?
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Transcript of Bipedalism: are we humans meant to walk?
BIPEDALISM: ARE WE HUMANS MEANT TO WALK?
A study of our evolutionary journey to bipedalism and the
consequences
Research Project Author: Beni Trainor
Tutor: Núria Batlle Class: 2n.1
Institut Montserrat de Barcelona
Abstract
Back pain is one of the principal ailments in our modern urban societies, which has
huge economic costs. The aim of this project is to consider the possible relationship
between back pain issues and the way we move. The project analyses, in a very basic
way, the evolution of movement and then focuses on bipedalism, which is the form of
locomotion of the human race. As a result of the study of fossils, hypothesis and a
professional opinion of paleoanthropology this project concludes where, why and how
our ancestors adopted bipedalism as their principal form of locomotion. Bipedalism
offered a great advantage for many reasons; however, there are also negative
consequences for walking as we do. With this said, the project analyses the various
anatomical changes that the body needed to adopt in order to support this form of
movement and, with the help of two professionals from the healthcare world, the work
concludes that back problems are strictly related to lifestyle and longevity. Humans
aren’t supposed to walk upright, or at least, not at the moment. Nevertheless, bipedalism
has provided humans with great evolutionary advantages, which have made us the way
we are today.
Resum
El mal d’esquena és un dels principals problemes de salut a la nostra societat actual que
provoca grans gastos econòmics. En aquest treball em proposo demostrar la possible
relació que existeix entre els mals d’esquena i la nostra manera de caminar. El treball
analitza, de forma bàsica, la evolució del moviment i seguidament es centra en el
bipedisme que és la principal forma de locomoció de l’ésser humà. El treball tracte de
demostrar quan, com i per què es va adoptar la posició bípeda amb l’ajuda d’estudis
fòssils, algunes hipòtesis i la opinió d’un expert en paleoantropologia. El pas al
bipedisme, tot i que ofería molts avantatges, també comportava algunes conseqüències
negatives. El treball analitza, tantmateix, els diferents cambis anatòmics que el cos va
haver d’incorporar per desenvolupar aquesta forma de locomoció. Aquesta part del
treball està recolzada en l’ajuda de dos professionals que treballen en el món de la salut.
La conclusió d’aquest treball és que els problemes d’esquena estan directament
relacionats a l’estil de vida y a la longevitat. L’ésser humà no està disenyat per a
caminar en posició erecta, almenys, no fins al moment. No obstant, no hi ha cap dubte
de que el bipedisme ha proporcionat als humans grans avantatges evolutius sense els
quals no seriem com som a l’actualitat.
Resumen
El dolor de espalda es uno de los principales problemas de salud de la sociedad actual,
que acarrea un gran gasto económico. En este proyecto, me propongo demostrar la
posible relación que existe entre los problemas de espalda y nuestra manera de caminar.
El proyecto analiza, de forma básica, la evolución del movimiento y luego se centra en
el bipedismo que es la principal forma de locomoción del ser humano. El trabajo trata
de demostrar cuándo, cómo y por qué se adoptó la posición bípeda con la ayuda de
estudios fósiles, algunas hipótesis y la opinión de un experto en paleoantropología. El
paso al bipedismo, aunque ofrecía muchas ventajas, también conllevaba algunas
consecuencias negativas. El proyecto analiza, así mismo, los diferentes cambios
anatómicos que el cuerpo tuvo que incorporar para desarrollar esta nueva forma de
locomoción. Esta fase del trabajo se apoya en la ayuda de dos profesionales que
trabajan en el campo de la salud. La conclusión de este trabajo es que los problemas de
espalda están directamente asociados al estilo de vida y a la longevidad. El ser humano
no está diseñado para andar en posición erecta, al menos, no hasta el momento. No
obstante, no cabe duda de que el bipedismo ha proporcionado a los humanos grandes
ventajas evolutivas sin los cuales no seríamos como somos en la actualidad.
Acknowledgments
In this section I wish to express my sincere gratitude to the people who have helped and
supported me while I was working on the project.
I want to give a special thanks to my parents who have helped me day and night since I
started the project until it was finished. I really appreciate all their comments, input and
support.
I also want to thanks to my tutor Núria Batlle for all her patience and support that she
has given me during the entire project and her help in correcting the work.
I want to offer my sincere gratitude and appreciation to Ester Sánchez González, to my
uncle Dr. Erich Koller and Alfonso Par for all their time and effort in answering my
questions and resolving my doubts.
Finally I want thank all the other people that have supported me and helped me to
complete this project and whom I haven’t mentioned specifically.
Table of contents
Introduction……………………………………………………………………………1
1. What is animal locomotion?………………………………………………………..2
2. What is terrestrial locomotion?……………………………………………………3
2.1. Limbless locomotion………………………….………….……………….4
2.2. Rolling locomotion……………………………….……………………….4
2.3. Legged locomotion……………………………….……………………….4
2.3.1. Types of posture…………………….…….………….…………5
2.3.2. Number of legs involved in locomotion…………….………….6
2.3.3. The function and structure of the leg and foot……….……….7
2.3.4. The order in which the limbs move……….….…….……….…8
3. Bipedalism………………………………………………………………..………..10
3.1. The Laetoli Footprints……………………………………………….…10
3.2. Lucy, the Australopithecus afarensis………………….…...……….….11
3.3. Ardi, the Ardipithecus ramidus……………………….……….……….12
3.4. Bone fragments from the Orrorin tugenensis…………………………13
4. Hypotheses……………………………………………………………………..…14
4.1. The Postural Feeding Hypothesis……………………………….....…16
4.2. The Squat Feeding Hypothesis……………………………………….16
4.3. The Savannah Hypothesis…………………………………………….17
4.4. The Energetic Efficiency Hypothesis…………………………………17
4.5. The Meat-eating Hypothesis………………………………………….18
4.6. The Carrying Hypothesis…………………….………………………18
4.7. The Heat Hypothesis………………………………………………….19
4.8. The Threat Display Hypothesis……………………………………..20
4.9. The Aquatic Ape Hypothesis……………………………………..21
4.10. Professional opinion…………………………………………..…22
5. Anatomical changes due to Bipedalism……………………………………24
5.1. The skull…………………………………………………………...25
5.2. The spinal column………………………………………………...25
5.3. The arms…………………………………………………………..27
5.4. The pelvis………………………………………………………….27
5.5. The Legs…………………………………………………………...29
5.5.1. The hip joint………………………………………..…...29
5.5.2. The femur……………………………………………….30
5.5.3. The knee joint…………………………………………..31
5.6. The feet……………………………………………………………32
5.7. Muscular changes………………………………………………..33
6. The consequences of upright posture…………………….……………....34
6.1. Facts and Statistics………………………….…………………..34
6.2. Healthcare professional’s opinions…………………………….36
6.2.1. Postural re-education specialist……………………...37
6.2.2. Orthopaedic doctor…………………………………..39
7. Conclusions……………………………………………………………….41
8. Annexes…………………………………………………………………...43
8.1. Annex 1…………………………………………………………43
8.2. Annex 2……………………………………………………….…47
9. Bibliography………………………………………………………………50
1
Introduction
Have you ever wondered why we have so many back problems? Has it ever occurred to
you that they may be related to evolution? I was watching a documentary recently
when, at some point in the program, someone said: “Back problems are caused because
we aren’t really supposed to walk upright”. That statement kept me thinking for a while,
as it had never really occurred to me before.
With this in mind I considered that this would be an interesting topic for my research
project. The objective of this work is to establish a relationship between back pain
ailments and the way we walk. However, the purpose of this project is not to find a
solution but to identify the problem and offer some practical recommendations.
I began by studying the basic mechanisms of how animals started to move and little by
little I have come to understand how our ancestors managed to stand up and walk on
two legs. The truth is there are no definitive answers as to where, when and why this
happened. However, Palaeoanthropologists agree that bipedalism started in Africa 5 to
6, or even 7 million years ago and that it was almost certainly as a consequence of
climatic change. There are several hypotheses trying to solve this puzzle, but to date
nothing is conclusive. Scientific researchers have all come to the same conclusion
which is that walking on two legs is known to have developed much earlier among our
ancestors than our other important attributes which make us the humans we are today.
When our ancestors adopted bipedalism as the principal form of locomotion a set of
skeletal and muscular changes needed to adapt the body to support this new form of
movement. I have studied what theses changes were and how they affected the body.
Finally I compared current facts and statistics related to back pain issues. In considering
the United States, Europe and Catalunya the figures are astounding. Experts in the field
have concluded that back pain, especially lumbar pain, will effect half the adult
population, cause major suffering and will result in huge economic costs to society.
2
1. What is animal locomotion?
Animal locomotion is the way living organisms self-propel themselves for survival. It is
the vital factor that makes the difference between living and dying. It is crucial to be
able to move for other reasons, such as finding food, a suitable habitat and to escape
from predators.
Energy efficiency is a very important factor that has to be considered in the movement
of a living organism. For example migratory animals that need to travel vast distances
using repetitive movement need a more efficient body structure to save energy. Other
animals that don’t migrate also need energy to produce bursts of speed and power.
Therefore efficiency is one of the most important factors that determines an animal’s
muscular and skeletal structure. Throughout centuries animals have evolved and
perfected their bodies to make them more efficient and we human beings are no
exception.
Animals have adapted themselves to move in almost all environments, from water and
air to underground caves. Since energy is the vital source for life it is important not to
waste it. Moving in an environment can present contradictions. If the environment in
which an animal is moving is fluid, air or water, energy will be used in maintaining its
balance. In terrestrial environments gravity presents a difficulty that may have to be
overcome.
Eadweard Muybridge
Animal Locomotion, Plate 700, 1887
Collotype
3
2. What is terrestrial locomotion? What types are there?
Terrestrial locomotion is the ability to move in a terrestrial environment, in other words,
movement on land. Scientific studies have proved that life began in the sea. The ability
to move in water made the effect of gravity irrelevant, but other problems arose from
the fact that swimming in water creates friction and therefore wastes energy.
When living creatures began to move from the sea to the land the friction produced by
water disappeared but the effect of gravity became more important. This originated in
the need to develop a propulsive mechanism for movement on land.
For this mechanism to be efficient and effective there are a few common requirements
that need to be present. The body of an animal would have to be sized and shaped
properly in order to provide for proper weight distribution throughout. These limbs
make up the supporting structure, which provides stability for the animal, and also
needs to be strong enough to exert sufficient force to make the animal move in reaction.
It is also important that animals can control the magnitude and direction of these
locomotive forces in order to accelerate, turn and stop without sacrificing excessive
stability. There are three main forms of locomotion common to terrestrial animals:
Legged, Limbless and Rolling.
This project will focus entirely on legged locomotion. I will present briefly what the
limbless and rolling forms of locomotion are and why they are important. Then, I will
concentrate on legged locomotion and bipedalism in particular.
4
2.1. Limbless locomotion
There are many terrestrial limbless vertebrate and invertebrate animals. These animals
may seem immobile due to their lack of legs, but they can achieve movement with the
underside of their bodies. All limbless animals have evolved from cold-blooded
relatives.
In the case of these animals the limbs are replaced by the underside of the body, in some
cases it can be dry and smooth like a snake or in others the body itself creates mucus
that helps move the animal. Other limbless species, such as worms and leeches, employ
different techniques to transport themselves through the environment they live in. For
example, leeches that anchor themselves with suction cups to move and snakes that
move the body sideways.
2.2. Rolling locomotion
A small number of animals use rolling as a means of movement
and sometimes use other forms as well.
Rolling animals can be divided into those that roll under the
force of gravity or wind and those that roll using their own power.
The animals that roll by the force of gravity normally use their own
bodies to form a ball, which they then roll when under threat. Other rolling animals not
only use this method for escaping from danger but also as a means of propulsion.
2.3. Legged locomotion
Moving with the help of limbs is the most common form of terrestrial locomotion. It is
the basic locomotion system for vertebrate animals and arthropods (insects). Not all
legged animals are the same. There are some differences. Important factors, which
differentiate animals with limbs, are their posture or way their body is supported by
their limbs, the number of limbs, and the functional structure of their legs and feet.
There are also differences in how animals move their legs when they are in motion, such
as walking, running or jumping. These forms of movement are called gaits and they are
energy efficient.
5
2.3.1. Types of posture
Terrestrial animals also need a solid structure to be able to support their body weight. In
order to achieve movement it is important that their limbs are well fitted to the body.
There are three ways these animals support their bodies, they are known as postures: the
sprawling posture, the semi erect posture and the fully erect posture.
Occasionally, depending on the circumstances, animals may use different postures to
give them an advantage. Take for example the situation where rabbits stop hopping
around and stand up, this allows them to increase their visual field.
It is important and interesting to know that, so far, no detectable waste of energy has
been discovered when there is a transition from one posture to another.
A) The sprawling posture
This posture is the first limb posture to have evolved and it
is from this one that the other erect postures originated. In
this posture normally the lower limb is held vertical and the
upper limb horizontal. If the animal is too large the upper
limbs may increase their angle allowing the body to move
without touching the ground but normally the body is
dragged along the ground. Examples of this case are
salamanders and lizards.
B) The semi-erect posture
This posture is interpreted as an extremely elevated
sprawling posture. Since sprawling was the first posture
to appear, the semi-erect posture very likely evolved from
it. Large lizards and giant turtles use this form of posture
to move.
6
C) The fully erect posture
This last posture is a typical characteristic found in
warm-blooded creatures such as birds and mammals. In
each case, however, the posture developed
independently. In this case the limbs support the body
weight vertically.
This posture is normally related to the fact that these types of animals, that is to say
warm-blooded, produce and maintain their own heat internally through the consumption
of calories (endothermy) and not externally by absorbing heat from the sun’s rays, as is
the case for cold-blooded creatures. This endothermic process results from a number of
metabolic functions. It allows the body to breathe and move simultaneously and,
therefore, extends the duration of activity, whereas in the case of clod-blooded animals
they require “warming up” between bursts of action.
The fully erect posture is understood to be the most recent one to have evolved, but that
does not mean that it is the best developed adapted to its environment. An example that
makes this evident is the evolution of the posture of the crocodile. This animal evolved
from a giant reptile that used the fully erect posture to move, but nowadays crocodiles
move with a sprawling posture. It seems that evolution has gone backwards instead of
forwards, but in fact evolution has adapted the crocodile efficiently to survive. Evidence
of their adaptability is that they are to be found in all the continents in the world (except
Europe).
2.3.2. Number of legs involved in locomotion
The number of legs involved in locomotion varies
greatly among animals. This ranges from animals
that use one leg to move to millipedes that use
hundreds.
Animals that employ unipedal movement are very
rare. One clear example of this is an insect called a
Springtail. Although it has six legs, it uses one special leg when it feels threatened to
jump away and avoid danger, and also, to jump to other leaves close by.
7
Animals that move with the help of two legs are called bipedal. Birds are a group that
are exclusively bipedal but there are a number of mammals that also use two legs to
move, most of those hop like kangaroos and jerboas. There are
also a few bipedal mammals that use combined ways of moving,
sometimes they can run others times they walk. Other species of
vertebrate and invertebrate animals are rarely seen walking on
two legs, but there are some exceptions: cockroaches and some
lizards can run on their two hind legs only when escaping from
danger.
With the exception of birds, all terrestrial vertebrate groups with
legs are mostly quadrupedal. Some insects are also quadrupeds but most of them are
hexapods. Having 6 legs or more is very helpful to maintain stability, as they are able to
maintain a triangle of support by using just 3 legs.
Starting with 8 legs, in the case of spiders, the
number increases considerably. The animals
that have the greatest number of legs are,
without doubt, the invertebrates, which range
from 14, in the case of crustaceans to
centipedes and millipedes that have hundreds.
2.3.3. The function and structure of the leg and foot
The legs of tetrapod animals, which walk on four legs, consist of an internal bone
attached to muscle and ligaments
forming the essential joints of the body.
These are: the hip and shoulder joints,
the knee and elbow joints, and the ankle
joints, where the foot is attached to the
leg.
In adapting to different environments the
limbs of animals vary greatly in size and
form. However, limbs of terrestrial
8
animals normally consist of the same bones and muscles. Even some primitive aquatic
animals share a similar limb structure to our own.
The basic form of the vertebrate foot has five toes, however some animals have
developed more or less than this standard. Feet have evolved in many different ways
depending primarily on the animal's needs. Important differences of foot structure result
from weight placement. Most vertebrates, such as amphibians, reptiles, and some
mammals walk on the underside of the foot; other mammals distribute their weight to
the toes, which allows them to move with a bigger stride and more speed. In some other
cases, animals such as horses walk on the tips of their toes. This further increases their
stride length and, therefore, their speed. A few mammals are also known to walk on
their knuckles; apes are an example of this.
The form of limbs among terrestrial invertebrates varies greatly. Arthropod legs are
jointed and supported by hard external armour, with muscle attached to the internal
surface. The other group of terrestrial invertebrates, velvet worms, have soft stumpy
legs supported by a hydrostatic skeleton, which is a structure consisting of a muscle
cavity filled with fluid.
2.3.4. The order in which the limbs move
Animals have a great number of ways of moving, which are used for different purposes
such as running away from predators. Those, which have four legs, employ three
different forms of motion: walking, running and leaping. Walking is the principal form
of motion, and is common to almost all legged animals. An animal is considered to be
running when, at some point, it reaches a “moment of suspension”, when no feet are
touching the ground. These moments of suspension are not only reached when running
but also when leaping.
There are many different kinds of gaits. Animals will use one or another to suit their
own purpose such as reaching a certain speed because of the terrain.
Humans have two important gaits, which they use to move: walking and running. But
under rare circumstances they may crawl to fit through tight spaces.
9
When walking or running animals normally alternate the legs of the two sides of the
body. In other cases animals alternate their front and back legs to move. Another gait,
which is different to the previous ones, is hopping, where the hind legs are together
when jumping.
Most animals position their heads in the
direction in which they are moving.
However there are exceptions. Crabs, for
example, can move sideways. Other animals
can move forwards and backwards with
equal facility and some only backwards. Examples of these are rats, when moving
through tight tunnels, and crayfish that move better and faster going backwards than
forwards.
10
3. Bipedalism
Bipedalism means walking with two limbs or legs. Humans nowadays move using a
bipedal stride but this has not always been the case. As a result of the discovery of
fossils in Africa, Palaeoanthropologists (experts in the study of anthropology related to
primitive man) have concluded that our ancestors walked on two legs.
Bipedalism has a number of adaptive advantages, such as energy efficiency. This form
of movement was developed independently among different animals. From very
primitive lizards that used their hind legs to run, to dinosaurs, birds, and mammals. We
modern humans are probably one of the last species to develop an upright stance but we
are unique in how we move; no other animal walks on two legs for its entire life as we
do.
For millions of years, the earliest hominids were a lot like other apes. They were short,
had tiny brains compared with modern humans, and could not speak or make tools. But
there was a profound difference that set them apart. They could stand up and walk for
long periods of time. Bipedalism was the first great transformation of our ancestors,
coming long before the evolution of all the other attributes that make us human.
We know all this thanks to the discovery of fossils. From the over 500 discoveries to
date, this project will concentrate on the most important of these, especially those that
are crucial to understanding how our ancient ancestors moved.
3.1. The Laetoli Footprints
At Laetoli in Tanzania (Africa), a set of two individual
Australopithecus afarensis footprint’s walking along
side by side have been dated to 3.6 million years ago.
As a result of the remarkable conditions of the terrain,
the footprints were preserved all this time. Ashes from
a volcano near by and rain created a wet material
similar to cement in which these two individuals left
their unique signature.
The footprints are identified as not fully human due to
11
the fact the feet had ape-like features, such as a slightly diverging big toe, but it proves
beyond doubt that millions of years ago our ancestors were already walking on two legs.
By analysing the volcanic ash researchers were able to conclude that the footprints were
around 3.6 million years old. During this time there could be two possible owners: the
Kenyanthropus platyops or the Australopithecus afarensis. It is very probable that the
Australopithecus afarensis were the ones to leave the footprints because of the
discovery of bones of these creatures nearby.
The discovery of the footprints and skeletal structures excavated at Laetoli showed clear
evidence that bipedalism preceded enlarged brains in hominids.
3.2. Lucy, the Australopithecus afarensis
Lucy is the common name of a fossil found in Ethiopia
(Africa) in 1974. It is of great importance because it is one
of the oldest ancestors and early hominids, the
Australopithecus afarensis, dating from over 3 million
years ago.
Although the recovery of the skeleton is not complete it
provides a clear image of what these ancestors were like.
Their dimensions were about the same size as one of
today’s adult chimpanzees and they had similar
musculature and brain sizes.
This evidence clearly reveals the discovery that the
Australopithecus afarensis had tiny brains in comparison to modern humans but they
were able to walk on two legs.
Lucy looked more or less like a chimpanzee. Her skull was
similar to a chimpanzee’s, but her pelvis and leg bones were very
similar to those of modern humans.
What makes this discovery so important is that it reveals that 3
million years ago these ape-like creatures were able to walk on
two legs rather than four. The valgus knee is one of the fossil
remains that reveal that the skeleton was in a process of
transformation: the arms were shortening and the legs were
beginning to grow longer.
12
Another detail, which indicated that Lucy walked on two legs, was that of a lumbar
curve, which meant the spinal column was starting to transform from an arch typical in
primitive quadrupedal ancestors to an “s-like” shape similar to that found in modern
humans.
3.3. Ardi, the Ardipithecus ramidus
More skeletal fossilised remains have been found since the discovery
of Lucy. Ardi is the name of the remains of the skeleton of an
Ardipithecus ramidus, an even older hominid than Lucy, aged about
4.4 million years old. The importance of this discovery lies not only
in its age, but also in that the skeleton is in perfect conditions. Most
of the skull, teeth, hands and feet are still intact.
Again Ardi, a 4.4 million year old hominid, is found to be bipedal.
This time, the feet reveal that she did walk on her hind legs because
they were flatter and better suited for this purpose.
The observation of the pelvic structure of this creature reveals its
saddle-like structure capable of keeping the torso in
balance when walking and of giving birth.
The reconstruction of the pelvis reveals relevant
human-like features. It isn’t as long as that found in
chimpanzees and the ilium (which is the blade
located at the top of the pelvis) is starting to twist
providing support for this new form of bipedal
locomotion.
13
3.4. Bone fragments from the Orrorin tugenensis
Even older fossils have been found in Africa. These
fragments found in Tugen (Kenya) are part of the lower
limbs of an Orrorin tugenesis, which lived around 6
million years ago. Only from these few fragments
recovered it was deduced that the legs were tilted
towards the centre of the body’s mass, typical of
hominids.
Several theories indicate that, indeed, this creature
walked on two legs but was also able to climb trees in
search of food and to escape from its predators.
14
4. Hypotheses
There are several theories or hypotheses as to how and why humans developed
bipedalism as a means of movement. At this stage there is nothing conclusive, because
there is not sufficient reliable proof to confirm one theory or another so it is a still a
controversial issue open to debate. The discovery of hominid fossils has been the key
factor in supporting these different theories. These discoveries all point to the same
conclusion: in human beings bipedalism was present well before any of the other
important human features, such as brain enlargement.
The most common hypothesis suggests that some 7 million years ago our ancestors or
hominids began to adapt to a much warmer climate. Drier savannas and woodlands were
replacing the huge forests of Africa. These apes needed to survive, so they stopped
climbing trees and began to walk long distances out in to the savannah to find food to
survive.
This project will analyse the most important and current theories proposed and will try
to make a case for the most convincing and plausible one supported by a professional of
the subject matter.
An important differentiation has to be made clear; bipedalism like many other forms of
locomotion first needed to be introduced as a posture. The first two hypotheses expose
different arguments as to how and why this happened. The following hypotheses are
concerned with the origin of habitual bipedalism; the order in which they are presented
is of no specific importance.
On the following page there is a diagram presenting the basic characteristics of these
hypotheses.
15
3. The Savannah Hypothesis
HYPOTHESIS OF THE ORIGIN
OF HABITUAL BIPEDALISM
PRINCIPAL OBJECTIVES
To free the hands allowing for the manufacture of tools and the
transportation of meat
4. The Energy Efficiency
Hypothesis
To develop an efficient form of locomotion for travelling long
distances
5. The Meat-eating
Hypothesis
To free the hands allowing for
the transportation of meat
6. The Carrying or Male
provisioning Hypothesis
To free the hands allowing male partners to provide and transport food for the family and to allow female partners a better way of carrying food
7. The Thermoregulatory or
Heat Hypothesis
By standing up and walking, hominids would avoid excessive heat on their bodies and improve
ventilation
8. The Threat Display
Hypothesis
To scare off predators by
appearing to be larger
9. The Aquatic Ape
Hypothesis
To develop an efficient form of movement in an aquatic
environment
1. The Postural Feeding
Hypothesis
HYPOTHESIS OF THE ORIGIN OF THE ERECT POSTURE
2. The Squat Feeding
Hypothesis
OBJECTIVE
To obtain food high up in the trees
To obtain food from the ground
METHOD
Standing up and placing the whole body weight on the hind limbs
Squatting down and gradually placing the body weight over the hind limbs
16
4.1. The Postural Feeding Hypothesis
Author /s: Dr. Kevin D. Hunt (1994).
Theory: This theory suggests that bipedalism developed as a feeding posture first and
then evolved into a form of locomotion. As a result of the study of early hominids and
chimpanzees, which are close relatives to modern humans, Hunt argues that our
ancestors started to stand on their hind legs in order to reach food that was higher up in
trees and bushes. These bipedal stances presented an efficient and effective way of
obtaining food and, within time, they were applied to other activities eventually
evolving into a form of locomotion.
Lucy the Australopithecus afarensis appears to have attributes that clearly reveal that
she could walk upright but not as efficiently as today’s modern humans. Her upper
limbs however indicate that she was indeed used to hanging from trees as Hunt
proposes.
4.2. The Squat Feeding Hypothesis
Author/ s: Jonathan Kingdon (1997).
Theory: His hypothesis suggests that bipedalism was not fully developed over a short
period of time but gradually introduced by squatting down to feed in forests rich in food
found on the floor. This new posture began to adapt the body for walking upright in the
future. The pelvis and legs were going to support more weight so they needed to be
adjusted for balanced standing. In this evolutionary change the arms were beginning to
lose their capacity to support weight and hang from trees. This theory suggests that
quadrupedal locomotion gradually became less efficient and was discarded through
natural selection.
At this point, we can certainly conclude that the erect posture evolved from either one of
the previous hypotheses. From this point on, the analysis of the other possible
explanations for the origin of habitual bipedal movement will be dealt with.
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4.3. The Savanna Hypothesis
Author/ s: proposed by Charles Robert Darwin (1871) and then adopted by Elizabeth
Vrba.
Theory: This hypothesis suggests that a few million years ago hominids moved out of
the jungle on to the large savannas. This adaptation produced the need to develop an
efficient form of terrestrial movement, which also would allow for hominids to carry
food and, further on, to handle
weapons for hunting. As the savanna
became the habitat of these early
hominids longer legs were needed to
assist better movement.
Elizabeth Vrba’s theory suggests that
this change that transformed the
African ecosystem from jungles to savannas was due to a period global warming. With
the study and observation of African antelopes she explains that ecosystems periodically
experienced significant losses, which then resulted in massive extinctions. She claims
that this could have happened with the African ecosystem, which, as a result, led to the
destruction of trees, leading hominids to acquire upright efficient walking.
Contradictions: The finding of fossilized primitive tools does not appear to provide
sufficient evidence to support Darwin’s Savanna Hypothesis because early hominids are
considered to have walked much earlier than the age of these tools would suggest.
4.4. The Energetic Efficiency Hypothesis
Author/ s: Peter Rodman and Henry McHenry (1980).
Theory: This hypothesis asserts an alternative explanation to the Savannah Hypothesis.
The climatic change, which forced hominids to move from dense forests to large
savannas, also created the need to move for finding food and survival. In this case the
hypothesis suggests that quadrupedalism was not efficient enough for travel and within
time it was replaced by bipedalism, which offered greater efficiency over longer
distances.
It sounds very convincing that one of the principal reasons for adopting bipedalism was
to save energy. As seen in the evolution of locomotion, energy efficiency is the vital
factor to support life.
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When hominids abandoned quadrupedalism they sacrificed stability, easier child
bearing and most important of all speed. So, in conclusion, there had to be a good
reason for adopting bipedalism over quadrupedalism and energy efficiency is a very
plausible explanation.
Contradictions: This hypothesis has some contradictions because indeed for modern
humans walking long distances on two feet is much more efficient than using four
limbs. But this form of walking was not developed at this stage among early hominids.
The human fossil record provides sufficient knowledge to prove it. Bipedalism was
present but it was still not as efficient as in today’s human beings.
4.5. The Meat-eating Hypothesis
Author/ s: Craig Stanford (2003).
Theory: This hypothesis is very similar to the popular Savannah Hypothesis and the
Energetic Efficiency Hypothesis. The difference that distinguishes this theory from the
others is its emphasis on eating meat. Stanford also proposes that there was a climatic
change in Africa 5 to 6 million years ago that transformed the environment from large
dense forests to broad dry savannas. Hominids were forced to travel long distances to
find sources of food.
Craig Stanford presents this model as a result of the study of chimpanzees and gorillas.
His main concern focuses on feeding situations, specifically when eating meat. He
suggests that early hominids needed to develop an efficient form of locomotion to find
and transport meat. This diet was probably one of the factors that led to the
development of brain enlargement.
4.6. The Carrying or Male Provisioning Hypothesis
Author/ s: Claude Owen Lovejoy (1981).
Theory: Lovejoy saw in bipedalism a great advantage in the ability for hominids to
carry food. As the East Africa climate was drying out some 7 million years ago, food
sources were becoming scarce and were to be found further and further apart. At that
time, hominids would have had to walk long distances to gather food for survival and
for feeding their offspring. This became a problem for females trying to raise their
young so the solution, according to Lovejoy, was that every male partner would care for
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their own female partner and the newborn, which in technical terms is called
monogamy. Bipedalism arose as a handy form of moving, leaving the hands free to
gather and deliver food to the family. The male partners travelled very long distances,
the female and offspring were left behind but they also needed to develop their own
form of movement to find and carry food locally. So probably bipedalism also
developed among females, according to Lovejoy’s hypothesis.
Lovejoy supports his theory using the argument of the differences between male and
female canine teeth and body size to prove that the Australopithecus afarensis were
monogamous.
In summary, Lovejoy argues that walking upright probably was developed for a number
of reasons. The factor that could have determined this change was most likely to do
with an alteration in the environment, which resulted in a change in food supplies.
When this change took place, bipedalism offered an advantage for those hominids to
survive.
Contradictions: Other evidence found in the two genders suggests a polygamous
mating system typical of chimpanzees prevailed at the time.
4.7. The Heat or Thermoregulatory Hypothesis
Author/ s: Dr. Peter Wheeler (1984).
Theory: He proposed a model in which bipedalism was developed in hominids because
of the heat of the savannah, which may have caused skin damage and dehydration.
Wheeler explained that by standing up cooler air could flow better allowing hominids to
feel more comfortable and to
eventually develop an efficient
evaporative cooling system, which
was simply sweating. This theory
also suggests that by standing up
less body surface was exposed to
the sun’s radiation, which was
intense near the equator, resulting in a reduction in heat absorbed. In the case of our
quadrupedal ancestors the whole back, head and even legs would have been exposed to
the sun, making it very hard for them to survive in high temperatures. Furthermore the
20
improvement of the thermoregulatory system for surviving in harsh conditions could
probably be the principal cause for fur loss.
4.8. The Threat Display Hypothesis
Author/ s: Joseph Jordania (2011).
Theory: This theory does not have much relation to other hypothesis presented.
Jordania suggests that bipedalism was developed as a form of defence strategy. Having
an upright position gave hominids an exaggerated appearance, which was used to scare
off predators and competitors. Jordania also thought that while standing up hominids
would try make loud sound signals to add to their threat defence strategy.
Jordania’s hypothesis interprets changes in body structure as a development to achieve a
better defence strategy. Longer and more adapted legs gave hominids the possibility to
stand up for a longer periods of time. Other morphological changes were acquired to
exaggerate their appearances even more. Furthermore rhythmic and synchronous sounds
were incorporated to their performances. Another important feature, which is also
present today in humans, was the development of body odour that could have been used
as a signal to ward off potential predators.
In summary, it seems odd but acceptable that our ancestors developed bipedalism
simply for warding off potential predators. When observing chimpanzees, our closest
relative, we can appreciate their form of lifestyle, which was probably similar to the one
of our ancestors. These creatures all live in large families as we do; they also eat,
reproduce themselves and even fight. When it was essential for these early hominids to
survive their main worries would probably have been to protect themselves and their
offspring. To achieve security for the family a well-planned defence strategy needed to
be developed. The idea of bipedalism being a defence strategy sounds hard to believe
but is understandable. Hard evidence substantiating this theory is scarce.
Contradictions: There are some contradictions to this hypothesis. Many animals use
warning signals when they feel threatened. Early hominids may have used these defence
strategies to alert of potential predators but there is little evidence to support this
argument.
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4.9. The Aquatic Ape Hypothesis
Author/ s: proposed by Alastair Hardy (1960) and championed by Elaine Morgan
(1982).
Theory: They both argued that there was a moment in human history when our
ancestors lived in an aquatic environment but then returned to land. During the time
they were in contact with the water, bipedalism and other typical modern attributes may
have developed. There is no solid evidence to support this theory but there are human
characteristics that Elaine Morgan suggests to have evolved during the possible
adaptation to water: high levels of subcutaneous fat probably were formed to help when
floating; the adaptation to breath during longer periods of time would have helped when
diving deep; and even the lack of hair would have assisted when swimming in water by
reducing drag.
This hypothesis provides a very doubtful explanation as to why we developed bipedal
movement and became efficient at it. The study and observation of evolution shows that
drastic developments can be developed as a response to changes in the environment.
Examples of this are terrestrial animals that began having aquatic lifestyles and
gradually developed limbs to move on land. If indeed human ancestors once lived close
to water and there developed bipedalism not as a form of land locomotion but as a form
of propulsion in water, why are we the only ones among primates to have lived there?
Why didn’t we stay in the jungle with the chimpanzees and gorillas? Given the
possibility that there was flooding, which obliged early hominids to develop certain
features to allow life on water, why only us and not all the terrestrial animals moved
into water? If flooding was not the cause that moved our ancestors to water, what was
the cause? It seems confusing the return to water after million of years of adaptation to
land for no reason.
In conclusion this hypothesis does not seem very feasible. It gives a reasonable
explanation for some of the human features that distinguishes us, but there is no solid
evidence to support that it was the only cause.
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4.10. Professional opinion: An interview with Alfonso Par, expert in
paleoanthropology
Alfonso has spent many years producing documentaries in the field of
palaeoanthropology. I discussed with him over a period of a few hours the hypotheses
regarding the development of bipedalism currently open to debate.
Initially he told me that bipedalism is neither a unique or new form of locomotion.
Many primates and small rodents are able to walk for short periods of time using their
hind limbs; this was also the case in hominids. When they started to develop an upright
stance it is very probable that is was not for the purpose of habitual movement. This is
supported by the fact that chimpanzees can move over short periods of time on two legs
and still move quadrupedally. So now we know that bipedalism was probably used for
other reasons before it became the principal form of locomotion for these creatures. I
am only concerned with the cause which made hominids adopt habitual bipedalism so I
won’t go into detail about the period before this happened.
Alfonso suggests that bipedalism did not develop as a result of one single cause; on the
contrary, he maintains that there were many causes that propelled these creatures to
adopt this form of locomotion. Therefore there are more than one hypotheses that are
valid and can be proven.
During the glacial ages, even though it seems surprising, seas sank causing droughts in
many of parts of the world. It is well documented that on at least two occasions in the
course of the history of the planet the Mediterranean Sea completely dried out.
Consequently the African ecosystem changed transforming the jungles into large
savannas, which were harsh and hostile. In order to survive, hominids needed to figure
out someway to obtain food, escape from predators and avoid excessive heat. The
solution was to adopt bipedalism as a habitual form of movement offering them a great
evolutionary advantage.
Alfonso suggests that the main cause for the development of bipedalism in hominids
was the need for them to free their hands in order to fabricate and manipulate tools used
to hunt and to transport food. The evidence that supports his opinion is the fact that
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chimpanzees on occasions fabricate tools in order to obtain food and that fossilized
tools were dated much later than bipedalism doesn’t necessarily mean hominids didn’t
fabricate tools. These arguments are to be found separately or together in the hypotheses
explaining the development of bipedalism.
As mentioned before, there were other reasons, found separately or together in several
hypotheses, which made hominids adopt habitual bipedalism. In the savannah the
climate was dry and extremely hot. Bipedalism offered a great advantage over
quadrupedal animals because it reduced the amount of sun radiation affecting the body.
Also, even though this form of locomotion was not well developed yet, the long
distances, which hominids needed to walk in order to obtain food, became easier to
achieve because it was more efficient. Additionally, when hominids stood up their
visual field increased and also their appearance was used to ward off potential predators.
Alfonso told me about another very interesting observation, which is included in one of
the hypothesis. When the dense forests started to dry out resulting in large savannas,
hominids adopted a new diet composed principally of meat because plants were scarce
and normally inedible. This diet was probably and very certainly one of the factors that
promoted brain enlargement because it provided a lot of proteins. Another factor, which
also probably affected brain enlargement, was the exercising of the brain in the tool
making process.
In conclusion, Alfonso suggests that bipedalism more than inconvenience is an
advantage for many reasons. He thinks many of the back pain issues are not related with
bipedalism itself but rather with our lifestyles. For example, fat people have a higher
probability of getting back pain than thinner people because their bodies have to support
a larger amount of weight, which they are not designed for. Additionally, Alfonso
argued that many of the back pain issues are directly related to longevity. People
nowadays live double and even triple the years compared to hominids, so it is common
sense to accept that the human machinery is way past its “sell by date” resulting in
many ailments, such as back pain, arthritis, cancer, etc.
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Morphological changes between chimpanzees and early hominids (Australopithecine).
5. Anatomical changes due to Bipedalism
Five to six millions years ago bipedalism as a new form of locomotion was adopted by
early hominids or Australopithecine, related to the Australopithecus. The reason as to
why bipedalism became a form of locomotion is proposed by several hypotheses but
with no definitive conclusion so far.
There are many anatomical differences between apes and modern humans. The first
hominids were very similar to today’s chimpanzees but as they started to stand up and
walk many morphological changes began to emerge. Bipedalism required a set of
anatomical changes to enable the support of the body weight and to maintain balance.
The most spectacular alterations are in the spinal column, the pelvis, the skull and the
feet. These changes were crucial to support and enable this new form of locomotion.
In the following sections the different anatomical changes humans have developed will
be considered.
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5.1. The skull
In order to walk upright and to increase the visual field the
skull needed to be attached to the spinal column in a better
balanced position. Now that the spine was straighter the
foramen magnum, which is the hole where the spinal cord
and vertebral column connect to the skull, was gradually
located more to the centre of the base of the cranium to
improve balance. In the diagram on the previous page there is
a clear difference between the connections of the spinal
column to the skull. In the case of the Australopithecine the connection is located in the
centre unlike in the case of the chimpanzees that have the spine connected at the back of
the cranium, holding the head at an angle. This transformation has helped to support the
weight of the cranium transferring much of it to behind the spine. It is a crucial
morphological improvement for the human lineage because it probably aided the
development of the brain and skull enlargement.
5.2. The spinal column
The spine changed from an arch-shape in chimpanzees to the shape of a “double s” in
humans. This change allows us to maintain balance in an upright position while moving
and keeping in sight surroundings. This transformation offers greater efficiency as it
requires less energy to maintain the spine in an
upright position.
It is important to keep in mind that as a result
of this development all the weight we would
probably be supporting on four legs we do
with only two. Another very interesting
observation that makes this change an
important in the evolution of bipedalism is the
fact that we can walk without transmitting too
much shock to the body. For every footstep we take the whole body weight is supported
by one of the limbs. The ground produces an equal and opposite reaction to the weight
bearing down with every step. Were the spinal column not to have evolved in this
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particular double-s way, the reactive force produced by the ground would create an
impact that would affect the entire skeleton.
The human spine has four main curves. The ones
that support almost all the weight and keep the body
erect are the lumbar and thoracic curve, which are
both located in centre of the torso. The thoracic
curvature is situated in the upper region of the torso
forming a backward bend and the lumbar curvature
in the lower region forming a forward bend both
completing an inverted “s”. The lumbar curve is crucial in allowing us to maintain
balance and to walk. This forward curve helps to keep the centre of gravity directly over
the feet and therefore allows us to maintain balance. In the past early hominids, who
still did not walk, had spines with an arched form making bipedalism not as efficient
and useful as it is to modern humans.
When observed the structure of the spine of the previous curvatures mentioned a big
difference stands out. These two curvatures have the biggest and thickest vertebrae and
intervertebral discs. This difference can also become a problem due to the fact that
these areas are the ones that receive greater stress and support more body weight.
The other remaining curvatures are the cervical curvature,
located above the thoracic curve, and the sacral curvature,
located below the lumbar curve. The cervical curve is
extended in the neck area and, therefore, its main purpose is
to support the weight of the skull. The sacral curve, however,
does not support much body weight. The main function of
this curve is to connect to the lower limbs and pelvic area.
An interesting insight in relation to this area is the fact that in
other animals it has much use. The ending of this part of the
spine is formed by what seems an undeveloped tail. This last
segment of the column, in most terrestrial animals, stretches and even adds more
vertebrae to form a tail that helps to maintain balance. The length of this tail varies
depending on how well balanced the body is. In the case of humans the need of a tail is
of not much use because we are already sufficiently well balanced.
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5.3. The arms
The arm structure hasn’t undergone many changes since hominids began to walk. The
main difference between modern human’s arms and their early ancestors is the fact that
arms were now no longer needed for locomotion and were used only for manipulating
objects. As a result, other changes took place. The scapula changed from a lateral
position to a dorsal position and the clavicle was bent forward to allow for greater
mobility in the forelimbs.
5.4. The pelvis
As a result of the study of pelvic fossils and the
pelvis structure of modern chimpanzees and
other apes, scientists have discovered that before
our ancestors stood up their pelvic structure was
very different. Primitive apes had a similar
pelvic structure to modern chimpanzees. As
these apes evolved and eventually started to
develop a bipedal stride their pelvis was
transformed strikingly as a result of the need to support weight and maintain balance on
two legs.
The pelvis is an anatomical structure that consists of four parts: two coxal bones, which
are called hipbones, located on each side of the lower torso and joined with a cartilage
disc (called symphysis pubis) forming the pubic area. These hipbones are connected
near the back to the sacrum
and its tail ending called
coccyx.
Each hipbone is formed by
three fused bones: the ilium,
the ischium and the pubis. At
birth these bones are separated
and within a few years they
fuse together forming a single
bone.
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When early hominids walked on four legs they had a different pelvic structure allowing
them to support strong muscles for climbing. This primitive pelvis may still be very
similar to the one found in chimpanzees and other apes.
The most remarkable attribute of primitive pelvises are their long narrow iliac blades.
These extend along each side of the sacrum in line with the spine. The structure of their
pelvises improved their way of moving through trees by attaching powerful climbing
muscles to the long iliac blades. Another characteristic of these creatures is a straight
narrow sacrum and coccyx.
The main difference that
sets apart these primitive
human pelvises from
modern ones are the
changes in the iliac blades
(ilium), which are part of
the hipbone.
Nowadays modern humans
have developed a pelvic
structure capable of supporting all the weight of the upper body and also, in the case of
females, capable of giving birth to babies with big skulls. This pelvic structure has
permitted the development of strong muscles, which allow humans the unique ability to
walk on two legs during long periods of time without wasting too much energy.
The modern human pelvis is much shorter than the primitive one but is wider forming
an efficient supportive system for bipedal locomotion. In this case, the ilium, which is
well connected to the sacrum, has a broader flattened blade extension coming out from
each side of the sacrum. This improvement provides stability and the ability to support
greater amount of weight using only two legs.
The reorientation of the ilium required two other changes, which were not a direct cause
of bipedalism. When the ilium rotated to support a greater amount of weight, another
problem arose. This was the need to hold together muscles and lower vital organs. For
29
this reason the sacrum, which separates the ilium at the back of the pelvis, has grown
wider and the ilium has changed its shape.
Underneath the ilium, the ischium and pubis are fused forming the pelvic structure. In
the ischium there is a crucial socket, called acetabulum that allows the femur to connect
and transfer the whole weight of the body to the legs. In the past this connection was
made further up on the ilium but as the femur needed to be connected in such a way that
it could support the weight of the torso and at the same time move, it needed to be
lowered.
Another important change was the flattening of the ischium that provided the ability to
be able to sit.
5.5. The Legs
The legs or hind limbs of all terrestrial animals are composed of three main parts, each
of which provides a crucial function to allow movement.
These are the femur, which is the most important bone for walking upright, and its
connections with the pelvis and the knee called hip and knee joint.
The shinbone is also part of the leg structure but it hasn’t suffered any significant
evolutionary change.
5.5.1. The hip joint
The hip joint is the connection between the
acetabulum and femoral head.
The main difference between the modern
human’s hip joint and the ones in early
hominids, who still did not walk, is that
humans need a larger hip joint to support
more body weight and to cope better with the
stresses produced while walking.
Previously, in the pelvis section, I have
mentioned that the acetabulum needed to be lowered to improve the support of the
weight of the torso during bipedal locomotion, but this adaptation was not the only one.
30
When early hominids started to walk upright there was a need to place the vertebral
column closer to the hip joints in order to provide a stable base for the trunk when in
motion.
In the diagram at the beginning of the section there is a clear difference between how
the body weight is situated. In the chimpanzee the body weight is more or less
distributed equally among the shoulder joints and hip joints. In the case of the
Australopithecine the weight of the trunk is placed above the hip joints, transferring the
whole body weight to these relatively unstable balls (femur head) and sockets
(acetabulum).
To solve this radical change there was a need to enlarge the hip joint so it could absorb a
greater amount of stress and accommodate a larger femoral head.
5.5.2 The femur
As mentioned in the previous section, when early hominids started to stand and walk
there was a greater amount of stress on their hip joints and femur.
The femur is the upper bone of the leg limb. It has three main components: the femur
neck, which is the long straight part, the head of the femur, which connects to the hip
joint and the distal end of the femur that articulates with the tibia and the patella
forming the knee joint.
Since bipedalism was adopted millions of
years ago the femur has suffered some
changes. There are two principal differences
between a femur of an Australopithecine or
modern human and one of a chimpanzee’s.
Human beings have a longer femur angled to
the midline allowing better support of the
body’s weight and to walk more efficiently.
Bipedalism created the need to balance the weight on only two legs. To do so the centre
of gravity needs to balance over each leg when walking. The femur, typical of modern
31
humans and early hominids, angles inwards so that the knee joints come closer together
placing the feet directly underneath the centre of gravity.
In the diagram at the beginning of this section there is a clear difference in how the
weight is distributed. In chimpanzees the weight is distributed evenly over four legs and
therefore there is not so much pressure on the hind limbs resulting in a straight femur
typical of the fully erect posture of terrestrial animals. In some occasions, they do stand
up but not as long as Australopithecines or modern humans.
5.5.3 The knee joint
The human knee joint has undergone similar changes to those concerning the hip joint.
With an increase of weight distributed on only two legs, the knees required more
support so they needed to be enlarged. The difference
between this lower joint is that because it is situated
almost directly under torso there is a greater amount of
pressure, thus knee joints are larger than the hip joints.
This adaptation provided a set of changes that would
make bipedalism more efficient. Now when walking
upright, the degree of knee extension is less in
comparison to that found in four legged animals.
Humans walk with their knees almost straight and, as a result, their function for this
action is to provide weight support.
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5.6. The feet
The adaptation of the feet to bipedal motion changed drastically their function and
structure. The main difference between the foot of a chimpanzee and an
Australopithecine is the size and shape. These factors are determined by the function
they serve. In the case of chimpanzees they need four broad hands and feet to be able to
walk but at the same time climb or grab food. When early hominids started to walk
upright, their feet developed over time the unique and principal functions of supporting
and stabilizing the whole body leaving the hands free for other activities. To fulfill this
purpose, the feet needed to develop a wider and
flatter structure that could act as a supportive
platform.
A foot is an incredibly complex mechanism. It
is composed of three main groups of bones: the
tarsal bones, the metatarsal bones and the
phalanges. The most important bones to be
considered are the talus and calcaneus bones,
which connect to the lower region of the leg
forming the heel, and the hallux or great toe,
which is crucial for propulsion.
The human foot has developed very important
attributes as a result of bipedalism. Now that there
was no need for grasping or grabbing, the toes lost
this ability and decreased in size. The same happened
to the diverged big toe or hallux. It was gradually
centred in line with the other toes but it maintained a
larger size in comparison to the other toes.
Other very important features, which contribute to the
propulsive system of bipedalism, are the foot arches.
In modern humans, these arches are larger providing a
more stable platform for the body.
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5.7. Muscular changes
When hominids started to walk, not only did bones adapt but also muscles. To support
this new way of movement the muscular organization needed to be changed. Two
important muscles, which in the past which were used in leg movement, called Gluteus
Medius and Gluteus Minimus evolved to serve as abductor muscles. The purpose of
these muscles is to help stabilize the body.
Also, when the femur length increased, the leg muscles responsible for motion were
modified. Each footstep a human takes the leg muscles situated at the ankle have to
propel the whole body weight. When we are about to take the next footstep there is not
as much muscle activity due to the fact that a longer leg provides a natural swing.
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6. The consequences of upright posture
Over the last few millions years humans have benefited from all the advantages
resulting from walking upright. We have been able to walk and run without wasting too
much energy; we have been able to create and manipulate a diverse array of tools to
improve life; we have been able to give birth to babies with large brains; and maybe
even walking upright has been responsible for promoting brain enlargement! But not all
is good news; there is a price to pay for walking they way we do.
A great number of problems arise as a direct consequence of standing up and walking.
Even though we are able to stabilize our bodies correctly our feet will ache and we will
injure our knees during our lifetime. Back problems are another important source of
injuries. We can twist and bend our spines while keeping our balance but yet we all
suffer from back problems at some stage in our lives. These painful consequences are
almost unavoidable.
6.1. Facts and statistics
It is important to keep in mind that the dates, which these facts and statistics refer to, are
of no great importance. What really stands out is the sheer magnitude of the numbers
both in human and economic terms that are directly related to back pain.
In the following sections I will consider facts and statistics from the United States,
Europe and Catalunya.
United States
According to the American Chiropractic Association, the Agency for Healthcare
Research and Quality, the Oprah Magazine, and to the Journal of the American Medical
Association:
• Lower back pain is the principal cause of work disability worldwide.
• Back pain is one of the most common reasons for sick leave. In fact, back pain
is the second most common reason of visits to the doctor’s surgery.
• Most cases of back pain are mechanical in origin, meaning they are not caused
by serious ailments, such as inflammatory arthritis, infection, fracture or cancer.
• Back pain is one of the most costly health problems in society. In 2005 care
costs reached $85.9 billion (109). According to the AHRQ, in 2007 a total of
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$30.3 billion was paid to providers, such as doctors, physical therapists and
others, as well as to pharmacies. Americans spend at least $50 billion each year
dealing with back pain issues. In total, spine treatment is a part of the $2.2
trillion (1012) healthcare industry.
• Experts estimate that 60% to 80% of the population will experience back
problems at some time in their lives. In 2007 alone, about 27 million US
adults aged 18 or older (11% of the total adult population) reported having
back pain.
• The 2008 survey presented by the Journal of the American Medical Association
asked a sample of approximately 23,000 people with and without back problems
about how much their medical costs were. Individuals with back or neck
problems spent on average $6090 in 2005, whereas healthy people’s medical
cost averaged $3056 in the same year.
Europe
According to the European Commission and the University of Oslo:
• Every month around 50% of Europe’s population report some kind of
musculoskeletal pain.
• Population surveys show that back pain is the most common type of pain in
young and middle aged adults, whereas knee pain is more common in older
people.
• The most common cause of sick leave and long term work disability in
individuals of working age is back pain and widespread chronic pain. This is
clearly a serious problem for those affected individuals and the resulting
economic cost for society is enormous.
• Rheumatic disorders, related to pain or disability of the musculoskeletal system,
represent nearly 25% of the Europe’s public healthcare budget.
“Musculoskeletal Problems and Functional Limitation” European Commission; Oslo,
October 2003.
36
Catalunya
According to the Generalitat de Catalunya and to l’Enquesta de salut de Catalunya
(ESCA 2006/ 2012):
• Rheumatic disorders are the leading cause of chronic pain. The most prevalent
ones are back pain and osteoarthritis.
• In 2005 29,6% of the population were reported to have suffered from back
pain –lumbar or dorsal-, 27,6 % from neck pain and 22,6% from osteoarthritis,
arthritis or rheumatic disorders.
• In 2007, these disorders were the second leading cause of work disability, which
led to 238.356 cases of long term work disability. This represents 20% of the
total and the principal cause was lumbar pain.
• In 2012 76,7% of the population from 15 years old and onwards is suffering
or has suffered some chronic ailment. The principal ailments are related to
illnesses of the musculoskeletal system (lumbar and dorsal pain, osteoarthritis,
arthritis or rheumatic disorders) and illnesses of the circulatory system (High
blood pressure, cholesterol, Varicose veins in the legs or bad blood circulation).
A precise breakdown between the two families of chronic ailments is unknown,
however it is clear from the numbers that it is a significant problem regardless.
• Back problems, migraine and allergies are the most frequent ailments found in
the age group between 15 to 44 years old. From 45 years onward this tendency
changes to back problems, osteoarthritis, arthritis and rheumatic disorders.
“Dia Mundial contra el Dolor” Generalitat de Catalunya- Canal Salut. 17/10/2008
“Enquesta de salut de Catalunya 2012” -Generalitat de Catalunya- Maig 2013
6.2. Healthcare professional’s opinions
I have had the opportunity to interview two professionals related to the healthcare
world. From all the facts and data I have seen and from all the anatomical changes and
hypothesis that I have studied I prepared a few questions for them to answer.
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6.2.1. Postural re-education specialist
The first expert I interviewed was Ester Sánchez González, a professional in postural re-
education. She answered a few questions that I had prepared for her in relation with
bipedalism and postural re-education. I was interested in having a professional’s point
of view on the development of the upright posture, which eventually would evolve into
bipedalism, and how this relates to back problems.
Ester believes the reason that made hominids adopt habitual bipedalism, although still
uncertain, was out of pure necessity, in other words, to survive. However she is
convinced that bipedalism requires much more effort than quadrupedalism and therefore
believes there had to be some selective pressure that made hominids adopt upright
walking.
When early hominids started to stand up and walk there was a set of anatomical changes
that needed to be acquired. Ester suggests that hominids little by little started to walk
and, in time, the muscles, which were responsible for maintaining the body upright and
permitting bipedal motion, became more adapted and therefore more efficient. Finally,
although these changes occurred over millions of years, the skeletal structure changed in
shape and position. During this period of time, Ester suggests that back problems were
not a big issue due to the fact that hominids alternated between walking upright and
walking using four legs so there wasn’t too much pressure on the back. This was also
because hominids still showed signs indicating that they had their knees flexed and their
pelvises still perpendicular, therefore the bodyweight wasn’t placed directly over the
back and legs but over a more forward position. She mentions that, in the beginning,
their backs were in kyphosis meaning they still conserved their curved spines and while
upright they walked similar to a hunchback.
As mentioned before, these ape-like characteristics changed with time. Nowadays when
modern human beings stand and walk upright the posterior muscle chain, which is a set
of muscles that, in spite of being separate, work as a whole, shortens, exaggerating the
physiologic curve of the spine. Therefore she agrees that we aren’t meant to walk.
As outlined in the section Facts and Statistics, the leading cause for work disability is
back pain and specially lumbar or lower back pain. This happens because if the pelvis is
38
not well positioned, the whole weight of the torso is placed on the lower part of the
spine, specifically between the L5-S1 vertebrae. The pelvis loses its ideal position
because the lumbar and dorsal muscles in charge of balancing the pelvis are being used
to hold the upright posture. Consequently the pelvis is moved backwards and the lumbar
column is curved resulting in the compression of the vertebrae and intervertebral disks
and an exaggerated lumbar curvature that will lead to future pain.
Ester agrees that most of these flaws in our design that lead to pain are related to our
modern lifestyle. Humans have adopted new habits in a relatively short period of time.
People nowadays are more sedentary and do not need to hunt or gather food and they
also have comfortable furniture. This “easy life” is responsible for shortening even more
the posterior muscle chain, which is in charge of holding the body up, and consequently
increasing the possibilities of having back pain.
When the human body is upright it will always need to shorten the posterior muscles
leaving the anterior muscles relaxed. This is not the only case, muscles work as
antagonists when executing an action, some muscles will extend while others will relax.
Ester proposes a solution based on some of these previous facts. She suggests that if
these shortening muscles were continually relaxed as a result of stretching the muscle
chain, the back wouldn’t suffer as much pain.
Ester makes a very interesting observation in relation to lifestyle. In the so-called
underdeveloped primitive societies back problems are not so prevalent because they
exercise much more their bodies. Ester suggests that if modern urban humans lived in a
more “natural” and active way they wouldn’t have so many back problems.
She told me an anecdote, which was very curious. The fact that human babies learn to
walk upright is strictly related to them copying the way their parents walk. Imagine the
case where a family of gorillas raises a baby, he will copy their way of moving,
although anatomically the baby would be prepared for bipedalism.
39
6.2.2. Orthopaedic doctor
During the time I spent in Munich working with my uncle, in a specialist medical
practice, I saw many people suffering from orthopaedic problems. Surprisingly, back
related problems in the spine and the surrounding muscles were the most common,
followed by injuries in the knee and shoulder joints. Another frequent problem was pain
related to the feet and degenerative processes in the hips.
All of these observations made me realize there had to be some link between some of
these "syndromes", pains and injuries and the fact that we are probably not supposed to
walk upright, or at least not finished evolving to do so adequately.
I prepared a few questions related to this matter for my uncle, Dr. med. Erich Koller,
orthopaedic specialist, to give his professional opinion.
Erich normally sees all kinds of injuries and pain-related syndromes. These are due to
traumas resulting from the practice of sports, daily life and domestic accidents. From his
experience, the most common pain syndrome is back pain. This is caused by all sorts of
injuries normally related to lifting weight incorrectly, bad walking habits, sitting for
long periods of time, bad postures during sleep, etc.
He suggests that walking upright may be the cause of back-related problems, however,
he highlights the effect of the modern lifestyle to the human body. He also agrees that
our bodies are meant to move and walk, so spending a lot time sitting without
exercising our bodies will eventually lead to problems in the skeleton, joints and
muscles. Erich also adds that excess weight is another big issue that causes many of the
problems, syndromes and pains mentioned previously.
Erich asserts that there is no quick solution to this problem; bipedalism has taken
millions of years millions to evolve and therefore to improve even more, millions more
years will have to pass. From his professional point of view he suggests that exercising
regularly, muscular training and stretching at least once a day will reduce most of these
pains. He also suggests that by walking with the right footwear these pains will be
reduced. Furthermore he recommends that preventing being overweight and obesity will
also reduce the number of people suffering back pain.
40
Erich proposes a possible modification to the body to improve its stability and reduce
back problems. He suggests that stabilizing the spine and knees, along with reinforcing
the muscles in the gluteal and hip area would be of great help when walking upright.
To sum up, Erich recommends that by being cautious and aware of the bad habits, such
as sitting all day long without moving, a lot of the problems regularly seen in his
medical practice would not occur.
41
7. Conclusions
Back pain is one of the most common ailments in modern societies. This results in a
great deal of pain for those who suffer it and has huge economic consequences.
As a result of the study of different aspects of the human evolutionary journey to
bipedalism and with the help of a professional of the subject matter I have come to the
following conclusion. The evolution of human locomotion experienced a drastic
divergence in relation to all the other members of our ape family. We managed to
develop an upright stance, walk and become efficient at it. Therefore, bipedalism more
than an inconvenience offered our human ancestors a great evolutionary advantage.
My initial objective was to establish a relationship between back-related ailments and
the way we walk. Thanks to the help of two professionals in the healthcare world and
after analysing the principal anatomical changes the human lineage suffered while
adopting bipedal locomotion I learned something very interesting. As mentioned before,
bipedalism served as an advantage during millions of years for our ancestors; but were
they or we properly adapted to support this form of locomotion? The truth is that we
aren’t meant to walk but it is to late to turn back, evolution made our decision for us
millions of years ago. However there is a bigger problem, which directly affects back
pain. Modern human lifestyles in conjunction with longevity exacerbate the underlying
design flaws of our bodies. Nowadays people live twice or even three times the years
compared to their ancestors. We also have no need to hunt or gather food so there is no
real pressure or need forcing us to move our bodies. Furthermore, comfortable furniture
and excess weight are factors responsible for increasing the number of sufferers of back
ailments.
Many of these problems are clearly and directly related to lifestyle. Modern urban
societies have great healthcare services, which permit us to live longer. Food
availability in nearly every corner of every town makes the task of hunting and
gathering food obsolete. Cars, motorbikes and public transport fulfil for most people the
necessity of transportation and so the general level of daily exercise of an individual is
minimal. In other words, people do not move anyway nearly enough to maintain a
healthy body and are becoming lazy.
42
Most aspects of the modern lifestyle are relatively beneficial for human beings but some
of our habits would need to change in order to reduce the great number of people
suffering from back pain. In order to improve this situation people should increase the
amount of exercise in a practical way that complements their daily routines. Simple
activities such as walking or cycling to work could make the difference between a
healthy and an unhealthy body.
The part of country’s healthcare budgets dealing with back pain costs billions of dollars
and euros. We visit regularly doctors, physiotherapists and chiropractors and spend a lot
of money on “repairing ourselves”. So this poses the question, what are governments
doing to resolve this problem? If only a fraction of the money spent on doctors and
pharmaceuticals were to be used in making people aware of the long-term consequences
of these bad habits, the number of sufferers would be reduced significantly. One
practical solution could be to educate children from an early age about being aware of
our design flaws and their direct long-term implications and promoting good lifestyle
habits to avoid future potential problems. This approach focuses specifically on back
problems but similar initiatives would also be very effective in dealing with, for
example, obesity. This could be achieved by teaching young children how to adopt and
maintain a proper and healthy diet.
I wonder if solving these problems is in the interest of everyone. Chronic diseases and
ailments provide drug companies and businesses related to the healthcare world with
huge incomes every year. So, are they really interested in solving the problem or are
they more interested in their profits? It is clear that the political will to implement long-
term beneficial preventative medical strategies through education is not evident and is
not a priority in our society for some reason!
43
8.1. Annex 1: Transcript of the interview with a Postural re-education
expert
I have prepared a few questions related to this subject for Ester Sánchez González,
professional in postural re-education, from the Centro de Colocación Postural Activa.
Although the interview was conducted in Spanish there is a section in which I explain
the most important observations and key ideas.
1. En relación al desarrollo de la bipedestación en los bebés, ¿Crees que los
primeros homínidos que llegaron a erguirse sufrieron los mismos problemas que
los seres humanos actuales? “La evolución hasta la posición erguida debió de pasar
por muchas fases y necesitar de muchísimo tiempo. No creo que fuese un cambio
brusco, sino paulatino y que estos primeros homínidos alternarían el ir avanzando en
dos patas con la marcha en cuadrupedia o casi cuadrupedia típica de los primates, que
se ayudan de los nudillos de sus manos para avanzar. Debió de ser un cambio muy lento
que por tanto, al no estar totalmente establecido, no produciría tanto acortamiento en sus
cadenas posteriores. Los primates descansan sobre sus patas posteriores pero se ayudan
con sus nudillos y sus piernas están flexionadas, por tanto los músculos de la cadena
posterior no están en tensión para aguantar la posición. Si las rodillas están flexionadas,
no podemos hablar de una contracción de la cadena posterior ni de músculos estáticos
como en el caso de los seres humanos actuales, que al tener que sostener el cuerpo en
dos piernas y mantener su equilibrio en ellas toda su cadena posterior está en tensión
para que se produzca el equilibrio. En el caso de los primeros homínidos, su peso se
desplazaba todavía demasiado hacia adelante, la cadera todavía no se había puesto
perpendicular y por tanto, su espalda estaba en cifosis, todavía no habían aparecido las
curvas fisiológicas, supongo, y por tanto, el eje estaba desplazado hacia adelante.”
2. Ya me contestaste a mi pregunta sobre si estábamos diseñados para caminar.
Me explicaste que el cuerpo humano, al erguirse debe acortar la musculatura
posterior exagerando la curvatura fisiológica de la columna. Entonces, si no
estamos diseñados para caminar, ¿Crees que este cambio tan radical fue un
cambio evolutivo (Darwin)? ¿O tuvieron que adoptar esta exageración muscular
para poder sobrevivir? (Teoría de la Savannah, Teoría del calor, etc.) “A esto no te
puedo contestar. Hay tantas teorías que te darían buenos argumentos para defender la
44
posición de Darwin como la Teoría de la Savannah. Yo creo que caminamos porque no
nos quedó más remedio. Lo que sí sé es que requiere mucho más esfuerzo caminar que
estar en cuadrupedia, como requiere mucho menor esfuerzo reptar que avanzar en
cuadrupedia. ¿Por qué dejamos de reptar y empezamos a avanzar en cuadrupedia?
Supongo que porque no quedó más remedio. Las especies, como sabemos, mutan por
pura necesidad y las que no mutan desaparecen. En cierto sentido, dejar de ir en
cuadrupedia y caminar en dos piernas fue una especie de mutación. ¿Por qué sucedió?
¿Por el calor? ¿Porque no había suficiente comida en los árboles para todos?”
3. Como dice Mèzierés: los músculos deforman los huesos y no al revés. ¿Estás de
acuerdo en que los primeros cambios anatómicos que los primeros homínidos
sufrieron fueron cambios en la musculatura (en concreto en la cadena posterior)?
“Creo que debió de suceder de esta forma: primero, cambiaron los hábitos de caminar,
moverse, etc.; después tuvo que adaptarse la musculatura a estos cambios y, finalmente,
los huesos tuvieron que cambiar su plano. Esto que parece tan increíble sucede
contínuamente en procesos naturales como por ejemplo el embarazo. Como sabemos, el
cuerpo de una embarazada sufre cambios posturales. El hecho de que el feto vaya
creciendo y ocupando espacio hace que el cuerpo de la mujer sufra cambios en su
pelvis. Además, estos cambios son necesarios para favorecer el canal del parto con lo
que la columna lumbar se deforma y se crea una hiperlordosis lumbar, un arco
exagerado en la columna lumbar. Pero la hiperlordosis es fruto de la necesidad de que el
feto debe salir por la pelvis, con lo que esta sufre un cambio, una anteversión.
Esto es una prueba más de que no estamos preparados para caminar erguidos. Las
hembras de otras especies mamíferas no tienen tanto problemas a la hora de parir a sus
crías. Además, la posición horizontal de su tronco favorece la protección del feto y su
expulsión. La piel en otras especies mamíferas está recubierta por pelo y una piel más
dura, mientras que en la parte anterior están los órganos vitales, y la piel es mucho más
suave y blanda. Pero resulta que en otros mamíferos el cuerpo al estar en cuadrupedia o
pseudocuadrupedia, como en el caso de los primates mayores, protege esos órganos
vitales, esa parte blanda queda protegida por el lomo de piel dura y por la posición,
mientras que en los humanos la parte anterior del cuerpo queda tan desprotegida como
la posterior, por tanto, tal vez todavía estamos en un proceso de mutación y falten
algunos cambios posturales por suceder.”
45
4. ¿Todos los problemas de espalda (en general) se deben al acortamiento de la
cadena posterior? ¿Crees que habría alguna forma de arreglar este problema,
aunque significara volver a caminar a cuatro patas? “Una vez adaptado un cambio
no se puede ir hacia atrás. El coste de ir erguidos ha significado dolor de espalda, pero
la ganancia ha sido importante: hemos sobrevivido como especie. Hay diferentes
cadenas musculares, la más importante en número de músculos es la posterior, pero el
acortamiento de otras cadenas musculares también afecta a la deformación del
esqueleto: por ejemplo, el acortamiento de la cadena lateral también provoca
alteraciones en la cadera. Además, los acortamientos en una cadena afectan
invariablemente a otras cadenas y favorecen su acortamiento.
Debido a mi trabajo, puedo decir que una solución es liberar contínuamente estos
acortamientos a base de estiramientos de las cadenas musculares, puesto que el cuerpo,
debido a su posición erguida, va a tender siempre a acortar los músculos de la parte
posterior y a dejar “fofos” los músculos de la parte anterior del cuerpo, porque así
funcionamos: los músculos funcionan como antagonistas y si un músculo de atrás se
tensa el de delante se pone “fofo”.”
5. Tuve la oportunidad de poder ver a varios pacientes en la consulta de mi tío,
especialista en ortopedia, que sufrían de dolores de espalda (donde más en la zona
lumbar) debido principalmente a malas posturas, esfuerzo físico, etc. Ocurre lo
mismo en tu área de trabajo? “Sí, es cierto, los dolores lumbares son los más
frencuentes debido a que todo el peso corporal recae entre las vérbrebras L5-S1 cuando
la pelvis no está bien alineada. Y la pelvis pierde su colocación “ideal” debido a su vez
a que nuestros músculos lumbares y dorsales necesiten estar en tensión para aguantar la
posición erguida. Esto provoca que la pelvis vaya hacia atrás y se curve la columna
lumbar, a que las vértebras se junten más y se curve de forma exagerada la columna
lumbar.”
6. Dejando a un lado los problemas de espalda. ¿Por qué hoy en día se sufren
tantos problemas musculares (relacionados con malas posturas)?¿Crees que la
gente en general debería mejorar su postura mientras caminan, están de pie y
hasta cuando duermen o se sientan? “Nuestros hábitos de vida y alimentación han
cambiado mucho en muy poco tiempo. Hacemos vidas más sendetarias, no necesitamos
46
ir a cazar para comer, hemos incorporado mobiliario que no hace sino favorecer aún
más el acortamiento de nuestros músculos. Hay sociedades, las mal denominadas menos
evolucionadas o primitivas, que no tienen tantos problemas de espalda: caminan
descalzos en suelos blandos que se adaptan a sus pies, se sientan en cuclillas para
charlar o comer, duermen en una especie de colchones a ras del suelo... Nuestros hábitos
han favorecido aún más si cabe nuestros acortamientos. Una vida más activa y más
“natural” haría que no tuviéramos tantos dolores de espalda, por no hablar de los
zapatos de tacón en las mujeres. Lo último que he escuchado es que un cirujano ha
tenido la brillante idea de amputar los dedos meñiques de los pies de las mujeres para
que éstas puedan calzar un zapato stiletto de un diseñador muy famoso de zapatos.
Según este “eminente” cirujano el dedo meñique de los pies no tiene ninguna función y
por tanto puede amputarse perfectamente. ¿Tal vez las próximas generaciones nazcan
sin ese dedo? No lo sé, pero tengo muchísima curiosidad por saber qué pasará con uno
de nuestros pilares básicos en la sustentanción del peso corporal, el metatarso del dedo
meñique con el dedo meñique incluido, por supuesto, y en cómo afectará este hecho a
nuestra colocación postural futura, de imponenerse el cambio tipo pandemia.”
7. Un poco por curiosidad. Dejando al lado la ley cefalocaudal. ¿Crees que un bebé
conseguiría una posición bípeda sin ninguna ayuda externa? ¿Si es así el caso, por
qué razón necesitaría desarrollar ese nueva forma de locomoción? “Sí que
conseguiría la posición erguida, tal vez con mucha más dificultad y tal vez con algunos
pequeños cambios al principio, pero como viviría en una sociedad donde todo el mundo
a su alrededor camina de forma erguida sólo por imitación podría erguirse. Ahora bien,
si un niño se criara con primates caminaría como ellos, aunque en potencia pudiera
caminar erguido.”
Otras preguntas
· Cómo se desarrolla la locomoción bípeda desde el nacimiento? “Siempre va desde
la cabeza hacia abajo: ley cefalocaudal. Lo primero que erguimos es la cabeza, el bebé
fortalece el cuello para poder erguir la cabeza, luego la musculatura dorsal, apoya los
brazos y los estira, después las piernas, debe fortalecerlas, debe gatear también para
aprender la marcha en cuadrupedia, finalmente se pondrá de pie.”
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· En un futuro: ¿la evolución muscular (o del esqueleto) mejorará el diseño
anatómico? “Yo creo que hablar de mejoras es mucho decir. Se ha hablado siempre de
un cráneo cada vez mayor y de que desaparece lo que no se usa o no se cree
imprescindible. Lo que sí percibo en las personas que acuden a mi Centro de
Colocación Postural Activa es que los dedos de los pies cada vez tienen una menor
movilidad debido a su poco uso. Puede que en un futuro no muy lejano los dedos dejen
de moverse y esto provoque cambios significativos en nuestras caderas.”
· Qué sería más beneficioso: ¿caminar o dejar de caminar? “En cuestión evolutiva
no siempre gana lo más beneficioso, gana lo que requiere un menor esfuerzo. Sólo que
si no hay opción: o morir o continuar erguidos, gana ir erguidos. De igual forma, si
nuestra supervivencia no está en juego, o no lo percibimos así, yo creo que ganaría no
caminar, porque nuestro cerebro no entiende que es más beneficioso caminar por la
salud, etc.”
8.2. Annex 2: Transcript of the interview with an Orthopaedic
specialist
Here below I have prepared a few questions related to this matter for my uncle to give
his professional opinion, Dr. med. Erich Koller, orthopaedic specialist.
1. From your experience, what is the most common injury or pain that people
suffer from? "We normally see all kinds of injuries and pain-related syndromes, due to
traumas in sports, daily life and because of accidents in the household. But the majority
of these are injuries in the knee/ankle area, followed by shoulder/hand accidents. The
most common pain syndrome would be the "back". All sorts of spine problems, due to
lifting incorrectly, bad walking habits, sitting for long periods of time, bad postures
during sleep, and so on. Then we have all kind of muscle stiffness from top to bottom.
Most in the hip and gluteal region, including hamstrings."
Do you think it is related to the fact that we haven’t successfully evolved for
bipedal motion? "Yes you could think so, I wonder if evolution still has not completed
the shaping of the human body concerning bipedal motion. We see way to many
48
problems with the back, spine, hip and knee joint, also trouble with feet and muscles.
But on the other side life and surroundings have changed so much over the last centuries
and decades that our body doesn't seem to fit into it appropriately enough.
Even if it doesn't look so at first sight our body is made for moving and walking! We
were designed to move around in nature at first hand."
"You see, we spend most of our time sitting: from home to work (bus/train/car), at work
(normally in front of the computer and/or at a desk), same on the way back, and finally
home - back to the chair or sofa again (PC, laptop, PlayStation, TV).
In general we do not move enough, that leads to a lot of problems in the skeleton, joints
and muscles.
Another issue is weight, better said overweight, causing many of the above mentioned
problems, syndromes and pains."
2. Could you suggest a solution to this problem? "Unfortunately there is no quick
solution to evolution (may take too long), but we (mankind) may develop further or
towards more sitting - who knows?
But from my point of view, the solution would be to move and exercise regularly,
people must do physical exercise, muscular training and stretching at least once a day.
This will also prevent or reduce cardiovascular risks, such as heart attacks, high blood
pressure or strokes.
All types of moving, using our body skills will help: walking, stretching, gymnastics,
swimming, biking, and so one. Not to talk about preventing overweight and obesity,
which are responsible for a lot of our daily problems in the practice too."
3. Should the appropriate musculature be improved or reshaped in such a way
that injuries resulting from walking are reduced? "Yes, as mentioned before, it is
important to move regularly to use your muscles and built up strong structures in order
to prevent damages and injuries. The use of the skeleton and the muscles (e.g. less
sitting) would improve many peoples back problems and avoid injuries."
Or should the skeleton be modified for the same purpose? "Well the problem is
rather that the skeleton has already changed over the last centuries. People in general are
growing taller, so the pivots and shifts on joints and the spine have definitively
increased, you can’t change that.
49
If possible, a better stabilisation of the spine and knees would help, along with
reinforcing the muscles in the gluteal and hip area. Walking is a good thing to do (avoid
using the escalator, lift and car) - if you do it right. Start slowly and - in order to do it
properly, walk with the right type of shoes."
4. Ultimately, if none of those suggestions proved to be successful, would you agree
that unless we change our form of locomotion these injuries are inevitable?
"In general injuries are unfortunately inevitable (sports, motion). You know, you walk -
even home, slip and fall or by doing so, just pull a muscle. There you go with an injury.
If we have more precaution and get people to be aware of their bad habits, e.g. get rid of
driving/sitting all day, then you avoid a lot of problems we see on a regular basis in the
orthopaedic daily life.
Or that our daily life changes to such an extent in the future that we drive and sit all day
anyway, being served by automats, just like in science fiction movies, then you would
avoid injuries!"
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9. Bibliography
Websites
· http://en.wikipedia.org/wiki/Animal_locomotion
· http://en.wikipedia.org/wiki/Terrestrial_locomotion
· http://www.geol.umd.edu/~jmerck/bsci392/lecture11/lecture11.html
· http://en.wikipedia.org/wiki/Bipedalism
· http://en.wikipedia.org/wiki/Laetoli
· http://en.wikipedia.org/wiki/Lucy_%28Australopithecus%29
· http://humanorigins.si.edu/human-characteristics/walking
· http://en.wikipedia.org/wiki/Ardi
· http://en.wikipedia.org/wiki/Orrorin
· http://emmagray.hubpages.com/hub/The-Many-Theories-Behind-Human-Bipedalism
· http://old.richarddawkins.net/articles/645378-study-reveals-why-our-ancestors-
switched-to-bipedal-power
· http://anthro.palomar.edu/hominid/australo_2.htm
· http://www.elucy.org/
· http://emmagray.hubpages.com/hub/How-Bipedalism-Has-Affected-The-Human-
Skeleton
· http://humanorigins.si.edu/research
· http://www.waterside-
hypotheses.com/UploadedFiles/Wading%20Paper/Supporting%20Files/model/s5_1_1.h
tml
· http://johnhawks.net/weblog/topics/bipedalism/why_be_bipedal.html
·http://www.maropeng.co.za/content/page/bipedalism_the_ability_to_walk_on_two_leg
s
·http://digitalcommons.iwu.edu/cgi/viewcontent.cgi?article=1013&context=socanth_ho
nproj
· https://en.wikipedia.org/wiki/Human_skeletal_changes_due_to_bipedalism
· http://en.wikipedia.org/wiki/Pelvis
· http://www.reasons.org/articles/the-leap-to-two-feet-the-sudden-appearance-of-
bipedalism
· http://anthropology.civilsprep.in/skeletal-changes-man/
51
Facts and Statistics
United States
· http://www.acatoday.org/level2_css.cfm?T1ID=13&T2ID=68
· http://backandneck.about.com/od/medication/a/Back-Pain-Prevalence-And-
Statistics.htm
· http://www.oprah.com/health/A-Cure-for-Back-Pain-The-Alexander-Technique
· http://meps.ahrq.gov/mepsweb/data_files/publications/st289/stat289.shtml
Europe
·http://ec.europa.eu/health/ph_projects/2000/monitoring/fp_monitoring_2000_frep_01_
en.pdf
Catalunya
·http://www20.gencat.cat/portal/site/canalsalut/menuitem.f039fb68a4311aec48af8968b0
c0e1a0/?vgnextoid=6daa590e7231d210VgnVCM1000008d0c1e0aRCRD&vgnextfmt=
detall&cod_noticia=94847&vgnextchannel=6daa590e7231d210VgnVCM1000008d0c1
e0aRCRD
·http://www20.gencat.cat/docs/canalsalut/Minisite/ObservatoriSalut/ossc_Dades_estadis
tiques/Estat_salut_estils_vida/Informacio_general_enquestes_salut/Enquestes_salut/Fitx
ers_estatics/Enquesta_salut_2012_edicio_maig.pdf
Books
· SLOAN, Christopher. La història de l’origen de l’home. 2004
· BOYD, Robert; SILK, Joan. B. Cómo evolucionaron los humanos. 1901
· CAMPBELL, Bernard. Human evolution. 1985, 1998