DIVISION OF GENERAL STUDIES

GST 213

HISTORY AND PHILOSOPHY OF SCIENCE

2 UNITS

2018/2019 SESSION

© DIVISION OF GENERAL STUDIES, USMANU DANFODIYO UNIVERSITY,

SOKOTO – NIGERIA.

COURSE OUTLINE
 TABLE OF CONTENTS

MODULE ONE: DEFINITION, HISTORY AND DESCRIPTION OF SCIENCE

Unit 1: Definition of Science

Unit 2: History of Science

Unit 3: Description of Science

MODULE TWO: MODERN SCIENCE, BRANCHES OF SCIENCE AND

CHARACTERISTICS OF SCIENCE

Unit 1: Evolution of Modern Science

Unit 2: Branches of Science

Unit 3: Characteristics of Science

MODULE THREE: PHILOSOPHY OF SCIENCE

Unit 1: Types of Philosophies of Science

Unit 2: Philosophical Positions of Philosophies of Science

Unit 3: Logic, Method and Epistemology

Unit 4: How Science Progress (Generation of Knowledge in Science)

Unit 5: Scientific Terminologies

MODULE FOUR: ORIGIN OF LIFE

Unit 1: Theories of the Origin of Life

Unit: Theory of Evolution

MODULE FIVE: ORIGIN OF MAN (Human Phylogeny)

Unit 1: Characteristics of the Order Primates

Unit 2: Special Features of Man

Unit 3: Conceptions on the Origin of Man

Unit 4: Controversy Surrounding the Theory of Human Evolution

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MODULE SIX: MAN AND NATURE

Unit 1: Man’s Influence on Nature

Unit 2: Man and his Environment

MODULE SEVEN: SCIENTIFIC METHOD

Unit 1: Steps in Scientific Method

Unit 2: Common Mistakes in Applying Scientific Method

MODULE EIGHT: RENEWABLE AND NON-RENEWABLE RESOURCES

Unit 1: Renewable Resources

Unit 2: Non-Renewable Resources

MODULE NINE: CONCEPT OF ENERGY

Unit 1: Forms of Energy

Unit 2: Man’s Energy Needs and Resources

Unit 3: Uses of Energy to Man

Unit 4: Energy on Earth

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 MODULE ONE
DEFINITION, HISTORY AND DESCRIPTION OF SCIENCE
Unit 1: Definition of Science
According to Wasagu (2004) in the past, attempts were made to define the word science.
And so far, there is no single definition that is acceptable to all. It is therefore much easier
to state and describe aspects of science. The following are some of the aspects of science.
i. It is a body of knowledge
ii. It is a process (as a method)
iii. It is dynamic (open to change)
iv. It is an institution
Science is universally regarded as an organized study of natural phenomena. It is now
acknowledged that the view which regards science in terms of its methods or products
or in relation to what scientist do is regarded as the dynamic view (Gilbert, Osborne,
Ferisham, Bajah & Okebulola, 1984).
However, scientist, educationalist and researchers individually contributed in
giving one definition or another and suffice here are the condensation of some of their
definitions;

 Science is the attempt to make the chaotic diversity of our sense

experience corresponds to a logically uniform system of thought (Einstein,
1940).
 Science is defined as activities culminating into testable, falsifiable and
verifiable body of knowledge (Abdullahi, 1982).
 Science is a discovering process that revealed relationship existing in
nature (Bajah, 1977)
 Science is an attempt by human beings to organize their experiment about
nature into meaningful system of explanations (Oguniyi, 1984).
To sum it all, Microsoft Encarta Encyclopedia Standard (2005) gave its definition as:
Science (Latin Scientia, from Scire “to know”) is a term used in its broadest sense to
denote systematized knowledge in any field but usually applied to the organization of
objectively verified sense experience. The pursuit of knowledge in this context is known
as pure science, to distinguish it from applied science which is the search for practical
uses of scientific knowledge, and from technology through which applications are
realized.
Unit 2: History of Science
The different kinds of knowledge acquired by primitive man were not at first classified
rather they were blended into a common culture. Science then was at the observational
and descriptive stage as man’s concern was in acquiring material for tools and equipment
for hunting and gathering food, which were his preoccupation. Also important for the

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primitive man was knowledge of the heavenly bodies as well as features of the landscape,
which were thought to have something to do with the abundance of food. This was the
Old Stone Age or the Paleolithic period. During this period, the basis of mechanics had
been established in the making and use of the necessary implements for the survival of
humanity. Also developed was the foundation of chemistry and biology in the making
and use of fire and in the knowledge of available plants and animals in limited habitats
which made him vulnerable to extinction as a result of changes in conditions that
determine the abundance of such animals, either due to climate changes or due to over-
hunting by man himself. This forced him into an intensive search for new kinds of food
such as roots and seeds of wild grasses. This eventually led to the invention of the
techniques of agriculture which is one of the momentous inventions in human history.
The growing of crops and the domestication of animals were thought to have evolved
simultaneously, with the former being a more far-reaching invention than the latter,
because without a stable supply of fodder, it is impossible to keep an adequate number of
animals in a restricted area. This was the Neolithic or agriculture era of human
history. The most revolutionary effect of this period was that it was possible for people
to live together in larger numbers thereby establishing villages and cities. The major
technical achievement of this era was the discovery and use of metals, particularly copper
and its alloy, bronze for the production of far more effective and durable implements,
utensils and weapons. The vanity of these metals however restricted their use to the
making of luxury articles and weapons while agricultural implements were still made of
stone. Nonetheless, this paved way for other occupations such as carpentry and masonry
on a large scale.
Unit 3: Description of Science
Science attained an independent status only in the 17th century AD, and had since then
undergone rapid changes both in its meaning and scope that any formal definition might
only express certain aspects of its growth. However, it could be understood through its
various descriptions given by different scholars.
Bernal identified five different aspects of science that distinguish it from other
field of human endeavor, these are:
i. Science as an institution (profession)
ii. Science as a method
iii. Science as a cumulative tradition of knowledge
iv. Science as a factor of production
v. Science as a source of ideas

i. Science as an institution (profession)

Although the institutionalization of science into a profession is a recent development, it
has already acquired so many characteristics of a profession that it is easier to recognize
who a scientist is. As a professional, the scientist worked in close association with 3
groups of people, namely; his public who collectively and severally determine what he
does. The patron provides the funds while the scientist’s colleagues provide the

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recognition and acceptance he needs. Eventually, it is the general public that gives
meaning and value to the work of the scientists.
ii. Science as a Method
It is often argued that science is the process of making discoveries rather than the
discoveries themselves. Although this process is not one fixed way of finding the truth,
some formal procedure lies behind the work of scientists. The first essential step in the
process is observation. Through observations, the scientist tries to find out things and
relations that are as far as possible independent of his sentiments. Definite ideas or
hypotheses are then formulated in the light of information gathered from these
observations. Next experiments are designed and performed to test the hypotheses. A
well-designed experiment always adds to knowledge even if it leaves some questions
unanswered or suggests new ones, in which case it enable one to think more about the
problem in different perspectives. The process then continues rather indefinitely, with
observations and hypotheses improved after each cycle, leading to progressively more
reliable knowledge, which is the best available for practical purposes, at the point in time.
The procedure constitutes what is otherwise known as the tactics of scientific
advancement. On the other hand, here is also what is called the strategy of scientific
advancement. This had to do with determining the choice and sequence of problem to
solve. Sometimes the problems are set by the socio-economic realities of the times or
arise from the application of earlier scientific ideas. At other times, the problems arise
from intrinsic interest of scientist.
iii. Science as a Cumulative Tradition of Knowledge
The cumulative nature of science distinguishes it from other aspects of man’s social
achievements. The methods of science would be of little use to the scientist if he does not
have at his disposal an immense stock of previous knowledge and experience. Although
not all of these are correct, they provide the working scientist with bases on which to
support his future progress. To know what is already known is not enough. To be a
scientist, one needs to add something of his own to the existing body of scientific
knowledge. Although other human institution like law, religion, philosophy and art have
histories and traditions which are in some cases older than those of science, they are still
not cumulative. They are either concerned with preserving eternal truths (as in religion)
or with individual performance (as in arts). The scientist on the other hand is striving to
change accepted truths, while his work (an individual performance) is soon assimilated,
superseded and lost. While great work of arts, music and literature are preserved in their
original results that of scientific work are incorporated in current science.
iv. Science as a Factor of Production
Man’s control over his environment is placed in stages (variously called the stone age,
bronze age, steam age, atomic age etc) each marked by the appearance of some new
material and techniques. Important as they are, materials have to be fashioned by man
before they can be of any use to him. It was in ways of extracting and fashioning
materials so that they could be used as tools to satisfy the prime needs of man that

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techniques arouse first, and then later became science. Science is thus the technical factor
of production. The other factors being material and economic
v. Science as a Source of Ideas
The conventional view of science describes its law and theories as legitimate or even
logical deductions from experimentally established facts. Contrary to this however,
Bernal (1971) argued that scientific laws, hypotheses and theories have wider bearing,
then the objective facts they claimed to explain. Most of them necessarily explain in large
part, the general non-scientific intellectual atmosphere of the time by which the
individual scientists is inevitably conditioned. These forms of thought can either lead to
valid scientific advances or become conditioned. These forms of thought can either lead
to valid scientific advances or become obstacle of scientific progress. The greatest
difficulty to discovery then is not so much to make the necessary observations, but to
break away from established traditional ideas in interpreting the observations. The
struggle between science and religion over Darwinian evolution for instance is not
essentially a scientific or even a philosophical one but a reflection of political struggle in
scientific terms. This notwithstanding, the progress of science depends on the existence
of a continuous traditional picture or working model (paradigm) of the universe. Such
paradigms are continually and often violently broken down from time to time and remade
in the light of new experiments in the material and social worlds.

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 MODULE TWO
MODERN SCIENCE, BRANCHES OF SCIENCE AND CHARACTERISTICS OF
SCIENCE
Unit 1: Evolution of Modern Science
A question that is often asked by science teachers is ‘when did science begin?’
No one has provided a satisfactory answer to this question because science was being
practice before Whewell defined it in 1840 as “the activities of people who work in
obscure and inaccessible laboratories with strange apparatus and using language which
only their colleagues understand” (Bernal, 1971). Early man observed natural phenomena
on its causes so as to find explanations for its formation in his primitive way. From pre-
historic to Greek times, man always wanted to understand the vagaries of nature: what is
the sun, moon, the stars, rocks, air and the living things on earth composed of? They
rationalized about the world around them. Nonetheless, between 4000 and 3000BC, the
‘ancient scientist’ were preoccupied with useful arts such as smelting, healing and
building. These arts were recorded in writing (Taylor, 1955).
However, since Greek philosophers began systematic reasoning, the beginning of
modern science is usually to the time of the Ancient Greeks, which began in the Greek
Ionian colonies about 600BC. The Greeks were taken as the pristine theoretical scientists.
Their studies were the predecessors of Biology, Chemistry Physics and Mathematics.
The Greek philosophers introduced the tradition of speculation which later formed the
basis of what would now be called scientific theories.
Such speculations or theories about the universe and the material composing it
began with Thales (C. 640-546BC). It must be mentioned that the Greeks had neither
laboratories nor observations. The only instrument or equipment they had was their brain.
And as there was always question about the material from which the universe was made
from, Thales proposed that water was the fundamental substance of all things. The
earth according to him was a disc which floated on the water below, and the water above
was the source of the rains. Thales theory that there was a primary substance of which all
things were formed received considerable acceptance.
A student of Thales called Anaximander (C, 611-547BC) proposed an opposing
theory by believing in a primary substance that was not identifiable with a known
substance. However, while another Greek philosopher Anaximenes (C.585-525BC)
considered air to be the primary substance from which all matters was derive,
Empedocles (C. 495-435BC) based his cosmology on four elements, namely earth, air,
fire and water. Any two or more combination of these elements might account for the
various materials present in the universe.
Socrates pupil, Plato (C. 428-347BC) introduced logic in his attempt to explain
and understand nature. He viewed the universe as having a geometric existence.
Therefore, he considered all the four elements propounded by Empedocles – air, water;
fire and earth-to compose of solid figures that were derived from triangles. He assigned
cube to earth, the tetrahedron to fire, the octahedron to air, and the eicosahedron to
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 water. He speculated on the fifth element the material forming the heavens, which he
assigned dodecahedron. Plato’s theory is the basis for modern chemistry as the regular
solids are utilized in chemistry today in the form of tetrahedral representations of carbon
and silicon atoms, in the representations of structure of coordination compounds, and in
the crystallography technique.
As one science historian believes, about eighty years after the death of Thales
around 465BC the philosopher Democritus (C. 470-380BC) was born. Democritus had
been called the ‘father of the atom’ because he was the first to conceive of the concept.
He developed a comprehensive atomic theory and demonstrated a clear foresight of many
details/facts, which were later, discovered by modern science. Democritus was credited to
be the first to use the word ‘atom’ which he derived from the Greek word atomnos
meaning something that cannot be further divided. He also postulated that everything
differed in size, shape and perhaps weight. Plato’s successors departed from his views of
the universe. Aristole (C. 384-322BC) viewed all things below the sphere of the moon as
composed of earth, fire, water and air. The four elements are qualities or properties rather
than substances. One element can be converted into another by the combination of two
opposite properties. Thus, there were four combinations:
The quality or property of the earth is dry-cold; of water is wet-cold, fire is
dry-hot and air is wet-hot. Through appropriate combinations of qualities; earth, water,
fire and air are interchangeable. The heavens, according to Aristotle, were composed of
the fifth element quintessence.
Greek philosophers were merely reasoning about the universe, and trying to discover
reasons why the world was as they conceived it. During this period of theoretical science,
there was not much of observing, or experimenting on ideas. Consequently, too often, the
Greek philosophers based beautiful theories on unsound data. Between 60BC to 1600AD,
conceptual science was Greek science because from all available records the Romans, the
Arabs and the men of mediaeval Europe did no more than to preserve and enlarge on
Greek ideals.
The demise of Greek science was brought about in the fifteenth, sixteenth and
seventeenth centuries when it was discovered that observations and predictions could not
be based on Greek theories, this meant that Greek science could not be used to explain or
predict natural phenomena. The scientists of the centuries starting from 1650 to the
present day have been preoccupied with providing.
1. Extensive and intensive descriptions of phenomena which occur in the universe,
2. explanation for these phenomena by establishing relationship which exist between them
and
3. establishing principles and theories for the predictions of these events.
The efficacy of the kind of science practices today is to be seen in our ability to control
events that occur within our environment and our understanding of the natural forces.
Modern scientists developed thermometer, barometer, microscope, telescope, air pump
and other applied science products in order to make the study of science more effective

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and to improve upon the reliability of information gathered. Thus, modern scientists were
mainly experimentalists and their results were used in the industrial development of the
advanced nations. By 1750 academic discipline of science had become institutionalized
and transcended national boundaries.

Unit 2: Branches of Science

Science can be divided into two main branches with some sub-branches as described by
Wasagu (2004).
1. Pure Science (Factual): - This is concerned with psychological pursuit of
theoretical knowledge, which is formal and deductive. Having sub-branches as
i. Formal Science, which is, classified as physical Science e.g. Mathematics,
theoretical physics, statistics, Algebra and Geometry.
ii. Empirical Science, classified as natural science e.g. Biology, Chemistry. Physics,
Botany and Zoology.
2. Applied Science (Professional): This is concerned with control, planning,
technological progress and utilization of the forces of nature for practical purpose.
i. Medical Sciences, which is characterized as medicine and Applied
Pharmaceutical Science.
ii. Technological Science characterized as Engineering and Agricultural sciences
e.g. Chemical, Mechanical and Electrical Engineering.

Unit 3: Characteristics of Science

For any study to be termed science, it must possess the following characteristics:
i. Objectivity and Testability; this refers to possibility of being check-up by anyone
ii. Reliability through verification; whenever tested, it turns out to be true.
iii. Definiteness and Precision; free from vagueness and ambiguity with the help of
measuring instruments and techniques.
iv. Systematic and Coherence in character; free from contradiction.
v. Comprehensiveness in scope; completeness in its explanatory power. (Wasagu
2004).

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 MODULE THREE
PHILOSOPHY OF SCIENCE
Introduction
According to Wasagu (2004) philosophy of science is a phase rather than a word; it is
therefore very difficult to define. In specific terms, philosophy of science is a field of
study that attempts to understand the meanings, methods, logic and methodological
analysis of the aims methods, criteria, concepts, laws and theories of science.
Philosophy of science is also concerned with pausing and attempting to answer
questions about the nature, validity and structure of scientific knowledge. It ask and
attempts to answer such questions as;
i. What is science?
ii. What is the nature of science?
iii. How does scientific knowledge differ from other forms of knowledge?
iv. How do we arrive at scientific truth?
The answers to these questions were already attempted.
It has been argued that the growth in the study and practice of science and the
emergence of diversification in the study of natural phenomenon gave rise to the vast area
of knowledge called the philosophy of science (Jegede, 1990). The development and
growth of this field were traced from Bacon to Hudson (1988) through Lakatos (1970).
Kuhn (1970) and Popper (1973) all indicated that philosophy of science as a field
concerned itself basically with unraveling the reasons (whys) behind human action and it
focuses on three major issues.
Namely:
i. Asking critical questions about what represent adequate scientific worldview,
ii. Analyzing science concepts in order to discover the logic and structure of science
and
iii. Describing what scientist does (Jegede, 1994).
Unit 1: Types of Philosophies of Science
There are basically two types of philosophies of science, namely;
i. Standard philosophy
ii. New philosophy
According to Jegede (1994), the standard and the "New" philosophies of science have got
distinctive characteristics which distinguish them into two categories as a result of
dynamism.
Standard Philosophy of Science
Philosophers such as Bacon, Hampal, Louise, Kant and Hume are concerned with
the analysis of configuration relations which hold between a scientific law and the
observation statement which confirmed or disconfirmed the law. The practitioners of
standard philosophy of science claim that:
i. Knowledge is additive and have bottom-up approach
ii. Observation remain the same, during scientific revolutions and
iii. The logical structure of the product of scientific research is very important.
iv. Objective criteria are therefore necessary for the validation of science discoveries.

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The New Philosophy of Science
Philosophers such as Lakatos, Kuhn and Popper discountenance formal logic as
the main tool for scientific analysis. They rely heavily on the use of history and
sociology of science for its analysis and holds discoveries as tentative while still
encouraging further search for more valid results, the practitioners of new or
contemporary philosophy of science claim that:
i. There is a reliance on a detailed study of science for the analysis of science while
resting on the scientific community on the ultimate decision to resolve any
controversial scientific issue.
ii. Science is characterized by two distinct phases; normal science which provide
areas of work for scientists who shape the belief of prevailing paradigm and
revolutionary science which leads to changes in paradigm which unseat incorrect
ones in revolutionary terms.
iii. Observations do not remain the same during scientific revolution; they are
generally governed by changes in paradigm.
iv. Continuing research and attendant criticism rather than accepted results and the
core of Science

Unit 2: Philosophical Positions of Philosophy of Science

The theory of knowledge always consists of concepts and knowledge as well as the
degree of their relationship and how it affects the organization of the mind. These
situations lead to opposing philosophical positions like Empiricism, Rationalism and
Constructivism.
i. Empiricism: One of the views that all the five sensory organs are identified by
scientists as the sources of knowledge. And that knowledge is acquired as a result of
accumulation and reconstruction of experience (Wasagu, 2004).
ii. Sensationalism: The hypothesis that all knowledge is derived through sensory
experience (e.g. Nose, Ear, Skin and Tongue).
iii. Reductionalism As viewed by empiricists believes that all complex ideas are built
out of basic stock of simple ideas and that they are in turn reducible to these basic
elements.
iv. Associationism; The theory that mental elements or ideas are connected by sequence
of experience.
v. Mechanism: The belief that the mind is characterized as a machine built out of
simple elements having ideas.
vi. Rationalism: This philosophical cognition sees reasoning as the prime source of
knowledge, which affect believe and action.
vii. Constructivism: The constructivists are of the view that people construct meanings
of what they do and recognize the importance of prior knowledge.
The above postulations are based on two assumptions
1. There should be memory images
2. Complex ideas are always formed 'by connecting one memory to another.

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Unit 3: Logic, Method and Epistemology
Philosophy of science is not only about the nature of science, but it is also about
methodology of science. It formulates and establishes principles of valid reasoning.
Logic refers to human reasoning or thought. It is equally concerned with the authenticity
of the inference and conclusion, which we make in our arguments. It is also the major
tool of philosophical reasoning, as well as reasoning in any area of knowledge. Reasons
deal with argument, judgment and inferences at the end.
It will therefore be correct to infer from a statement that says Sokoto is in the
Northern part of Nigeria. Thus, Tambuwal is found in Sokoto State; therefore, Tambuwal
is in the North. We cannot validly infer 'that Tambuwal is not in the North.
Aristotle formulated three laws of thought that are acceptable for reasoning, these are:
i. Law of non- contradiction; dealing with correct proposition; example
a. All dogs have one tail
b. My dog freedom has one tail
ii. Law of excluded middle; each proposition is either true or false; example
a. All dogs have six legs
b. My dog freedom has four legs
One statement is true, .one untrue.
Law of identity; each proposition implies itself; example;
a. All dogs have six legs
b. My dog has six legs
Both statements are false if (a) were true (b) would be.
Methods: (Induction versus deductions). In scientific methods, reasoning could either be
inferred inductively or deductively. Inductive reasoning is simply the process of arguing
from singular proposition to general proposition e.g. from observation that revealed
several oranges to be sweet led to conclusion that all oranges are sweet. On the other
hand, deductive reasoning is the reverse process of arguing from universal or general
propositions to singular or particular propositions. Conclusions from hypothesis are
deductive in nature, hence logically sound and reliable.
Epistemology: Means theory of knowledge. It concerned itself with the definition, nature
and the structure of knowledge. Epistemology is important in the process of discovery
and research. Epistemology is also concerned with sources of knowledge namely:
 Revealed Knowledge (through revelations)
 Empirical Knowledge (through human senses)
 Rational Knowledge (through reason)
 Intuitive Knowledge (through human intuition and instinct)
 Authority Knowledge (through books and the works of scholars)

Unit 4: How Science Progress (Generation of knowledge in science)

Kuhn has identified a number of stages through which science passes (two of the
stages, normal science and revolutionary science are considered to be the most
important).
These stages are nearly reformulated by Mark Richardson below:

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1. Pre-scientific stage (Pre-Paradigm Periods)
This stage is characterized by the co-existence of many different theories all attempting
to explain the phenomenon resulting in a variety of different explanations of the
phenomenon and related facts. Research in this period is unguided, full of uncertainly,
and no coordination, every view is on its own.

2. Emergence of Paradigm (Paradigm Period)

Eventually a theory or group of theories emerges as being successful than the rest, having
the following characteristics.
a. Its achievement must be great enough to attract competing practitioners.
b. It must be open-ended enough to leave all sorts of problems be solved
c. It must lead to a research tradition, by providing a working model, of how to do
science.
Within the period, dominant theories emerged and consensus are reached.

3. Normal Science
This stage is described by Kuhn as working within a paradigm. It ends the fruitless debate
between competing theories and permits the establishment of an agreed set of standards
and procedures as well as agreement on the meaning of terms.

4. Crisis and Extra Ordinary Science

A feeling of crisis begins to be experienced that leads to a period of extraordinary
science, which in many ways resembles the pre-scientific stage. Competing theories
arises again and the consensus that existed before disappears. Everything is questioned
and meaningful debate between the raw competing theories becomes difficult if not
impossible, because different approaches, concepts and ideas are used by the competing
theories. But eventually new paradigm begins to emerge.

5. Revolutionary Science Stage

This stage is characterized by the emergence of the new paradigm. The concept of
revolution is central to Kuhn’s idea. The old system is considered to have failed, but the
emergence of the new one is resisted. Polarization takes place between the old paradigm
and the new Paradigm with each side talking its own languages and unable to
communicate with the other.

Unit 5: Scientific Terminologies

Scientific Facts
It is important to note that there is a difference between scientific facts and
everyday facts. It is clear that there is more to seeing than meets the eyeball; to see is to
interpret. Seeing is not passive reception; it is an active exercise in problem solving.
What we regard as the fact in science depends upon the expectation and sensory
apparatus contributed to our conceptual patterns of organization.
One can say without any fear of contradiction that the concept of 'Fact' is problematic;
therefore facts can be summarized as follows:
i. A statement of fact is dependent on the instrument of observation

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 ii. Facts are subjective statements that depend on sense perception.
iii. Facts exist only to the degree of the perception of the individual and phenomenon
in which it is discussed.
iv. Facts are statements which relate theories and particular events and which may
include certain-conventions.
v. Facts are subject to modification, to say they are tentative statements in science.
vi. Facts are not simply accumulative as science instead they change or evolve or
may disappear to be replaced by others.

Scientific Laws (Generalization that are based on particular events)

Scientific laws are generalizations, which sums up all facts established. Therefore
the best law is due to the quality of the facts. As soon as the facts fail the laws may flop.
Scientific laws are not ultimate truths, which have been discovered in nature but instead
are idealization created by scientists to describe approximately patterns discerned in the
environment. However, scientific laws are not more firmly established than the facts.
They generalize and in a number of respects are less certain than facts. This uncertainty
in laws arises out of their claim to be applicable to the unknown.

Scientific Theories
Scientific theories are usually considered to provide an explanation of particular
facts and laws. It should also enable new facts to be predicted, and give a sense of
understanding of the facts and laws it explains. The issue of where theories come from
always attracts the attention of Science Education Students. Abdullahi (1981), pointed
out that theories are human creations and unlike other theories have to survive a detailed
confrontation with experiments.
However, evidences from the History of Science imply that theories are arrived at
quite differently. Many theories are usually attributed to imaginative insights which are
then developed by careful conscious thought. A number of scientists have described how
they arrived at their theories in just such terms. Among them is Kekule who claimed that
he arrived at his idea of a ring structure for the benzene molecule when dozing in front of
a fire. Also professor Gabor said that the crucial idea that lead to his discovery of
holography came, while he was watching a game of tennis.

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 MODULE FOUR

THE ORIGIN OF LIFE

Introduction

The issue surrounding how life originated has been a point of controversy among
different categories of individuals who are interested in the subject. Traditionally, the
study of history of life has been fraught with allegations of indoctrination. Indoctrination
may be defined as a conscious attempt to inculcate unshakable commitment to a belief
or doctrine. Such approaches are not only unscientific but also intellectually dishonest.
Much of the evidences on which range of opinions on the subject are based is
metaphysical. This implies that it is impossible to repeat the exact events of the origin of
life in any demonstrable way. This is true of both scientific and religious accounts.
However, evolution is the only theory concerning the origin of life that appears scientific.
This is because it is made up of a collection of scientific hypotheses that are capable of
being tested. Subsequently, we shall see some of these theories and evidences as
presented by different individual scientists, who have contributed to the subject.

Unit 1: Theories of the Origin of Life

Theories dealing with the origin of life on the Earth (on which man lives) and indeed the
entire universe are diverse and uncertain. There have been divergent views about the
origin of life. The argument had been between the scientists and theologians, Science,
contrary to popular belief, can not contradict the divine origin of life. Nor theological
view necessarily dismisses the scientific hypothesis, that during the origin of life, life
acquired those characteristics which are explained by the laws of science. The major
theories that have been put forth accounting for the origin of life on Earth include;

a. Special creation: - (i.e. life was created by a natural being at a particular time)
b. Spontaneous generation: - (i.e. life originated from non-living matter)
c. Steady state theory (i.e. life has no origin)
d. Cosmozoans theory (i.e. life moved on to these planet, Earth, from elsewhere.
e. Biochemical evolution theory (i.e. life arose according to chemical and physical
laws.

a. Theory of Special Creation

This theory is supported by most of the world’s major religions (especially, Islam and
Christianity) and civilizations. It attributes the origin of life and indeed man to a
supernatural event at a particular time in the past. According to this, theory, God created
man in his own image. In other words, the diversity of forms as seen among and within
organisms are not as a result of either convergent or divergent gradual changes from an
earlier structure or form; rather they were created spontaneously, just as we find them.
For instance, archbishop Usher of Armagh in support of this theory, calculated in 1650
A.D. that God created the world in 4004 B.C, beginning on October 1 and finishing with
Man at 9.00 a. m. on October, 23rd . He achieved this figure by adding up the ages of all
the people in the biblical genealogies from Adam to Christ. Though the arithmetic is

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sound, he placed Adam to have lived at a time when Archaeological evidence suggests
that there was already a well established civilization in the Middle East. The traditional
Judo – Christian account of creation given in Genesis 1:1-26 has attracted and still
continues to attract controversy. The view about special creation as presented in this
theory to scientists lacks empirical basis because it cannot be subjected to any form of
testing.
b. Theory of Spontaneous Generation
This theory was prevalent in ancient Chinese, Babylonian and Egyptian thought as an
alternative to special creation. Aristotle (684-322 B.C) believed that life arose
spontaneously. His hypothesis of spontaneous generation assumed that certain particles
of matter contained ‘an active’ principle’ which could produce living organism under
suitable condition. His active principle includes the fertilized egg. With the coming of
Christianity, the spontaneous theory became less acceptable except those who believed in
magic and devil worship, though it remained a basic idea for a long period afterwards. A
number of people, through series of experimentation and observation, disproved the
theory of spontaneous generation.
c. Steady State Theory
This theory asserts that, the Earth had no origin, has always been able to support life, and
has changed a little and that species had no origin. The theory proposes that species too,
never originated, the only alternatives are for its numbers to vary or for it to become
extinct. The theory does not accept the paleontological evidence that the presence or
absence of a fossil indicates the origin of extinction of species. The paleontological
evidence presented in support of the steady state theory describes the fossils appearance
in ecological terms. For example, the steady state theory believed that, fossilization is
only favoured in an increased population or movement of the organism into an area that
favoured fossilization.
d. Cosmozoan Theory
This theory does not offer a mechanism or account for the origin of life but favours the
idea that, it could have had an extraterrestrial origin. It does not therefore constitute a
theory of origin as such, but merely shifts the problem to elsewhere in the universe. The
theory states that life could have arisen once or several times in various parts of our
galaxy or the universe. Repeated sightings of café drawings, of rocket-like objects and
specimen provide some evidence for this theory.
e. Biochemical Evolution
This theory has its root in the belief of astronomers, geologists and biologists that the
Earth is about 4.5-5.0 thousand million years old. Many biologists believe that the
original state of the Earth bore little resemblance to its present day form and had the
problem of appearance. It was hot (about 4000-80000oC).

Unit 2: Theory of Evolution

The concept of evolution did not start with Darwin, when he published “the origin of
species” rather it had been a point of discourse among several philosophers. The
historical background of the theory of evolution reveals that the concept of continuity or

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gradual development of more complex species from pre-existing simpler forms had
occurred to several philosophers and natural historians before the declaration of
evolutionary hypotheses were put forward in the early 19th century. Let us now examine
two of these theories as proposed by Lamarck and Darwin.

Lamarckian Theory on Evolution

Lamarck, a French biologist proposed hypotheses to account for the mechanism of
evolution based on two conditions. These are,
i. The use and disuse of parts and
ii. The inheritance of acquired characteristics.
According to him, changes in the environment may bring about changes in behaviours
and this may lead to changed patterns of behaviour which can bring about use or disuse
of certain organs or structures. Extensive use would lead to increase in size and/or
efficiency (e.g. the body of an athlete as compared to the body of an individual who
does no exercise). While disuse will lead to degeneracy and atrophy. These traits that
are considered heritable can be transmitted to the next generation. In order to explain this
theory, Lamarck said the long neck and legs of the modern giraffe was due to the short
necked and legged ancestors feeding on leaves of tall trees. The long neck and legs were
then passed on to subsequent generations. He also explained the webbed toes of aquatic
birds to constant use of the toes ﴾legs﴿ for swimming and extended the skin in between
the digits. Similarly, the characteristics were passed on progressively to successive
generations. Lamarck’s theory provided basis for the acceptance of concept of evolution
but his mechanism of change was not widely accepted. Lamarck’s emphasis on the role
of environment in producing phenotypic changes in individuals was correct. For instance,
body building exercises will increase the size of muscles, but this trait cannot be
transmitted to the next generation because it is not genetic. To show this, Weismann cut
off the tail of mice over many successive generations. According to Lamarck, this would
have led to the production of progeny ﴾offspring﴿ with smaller tails. These were not the
case. Weismann then postulated that, body acquired characteristics (resulting in
phenotypic changes) did not directly affect gamete and cannot be terminated to the next
generation.

Darwin and Wallace on the Origin of Species

Guided by the publication of reverend Thomas Malthus on principles of population
(which highlighted the consequences of reproductive potential of humans), Darwin
observed that under intensive competition of numbers in a population, any variation
that favoured survival would increase that individuals ability to reproduce and lead to
fertile offspring. Less favourable variation would lead to decreased number of such
individuals in the population. This provided Darwin the framework to formulate a theory
of evolution by “natural selection”. Wallace, another naturalist like Darwin, working
almost at the same time wrote on the same subject matter which was sent to Darwin,
which led to their joint presentation in 1858. A year later, Darwin published his work on
“origin of species by means of natural selection”.

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Natural Selection
Darwin and Wallace proposed that natural selection is the mechanism by which new
species arise from pre-existing species. This theory hypothesis is based on three main
observations which may be summarized as follows:
i) Individuals within a population produce averagely more offsprings than are needed to
replace them.
ii) The number of individuals in a population remains approximately constant. This
means that many individuals fail to survive or reproduce. Hence, there is a “struggle for
existence’ within a population.
iii) Variation exists within all populations. This means that in the “struggle for existence”
those individuals showing variations best adapted to their environment have a
“reproductive advantage” and produce more offspring than less well- adapted organisms.
Struggle for existence or the hypothesis called natural selection provides the mechanism
accounting for evolution. According to Darwin, favourable variations will be inherited by
the next generation. Unfavorable variations are selected out ‘or “selected against” the
present, conferring a selective disadvantage on that organism. In this connection, natural
selection leads to increased vigour within the species and ensures the survival of that
species.

Misconceptions about Darwin’s theory of Evolution

Many misconceptions have grown up around the theory of evolution as outlined by
Darwin; these misconceptions may be summarized as follows:
i) Darwin made no attempt to describe how life originated on earth. His major concern
was on how new species might arise from pre-existing species.
ii) Natural selection is not simply a negative, destructive force but can be a positive
means of change in a population. The struggle for existence was characterized by
unhealthy terms like ‘survival of the fittest’ and “elimination of the unfit” by the
philosopher Herbert Spencer and the press of the day.
iii) The misconception that humans (man) evolved from the ‘apes’ by some linear
progression was over sensationalized by the press and offended both the religious and
secular communities. The former saw this as an insult on their belief that “man’ was
created in the “image of God” while the latter were unhappy by the apparent undermining
of the ‘superior position’ of humans (man) within the animal kingdom.
iv) The apparent contradiction between the Genesis six-day creation account and the
progressive origin of species viz-a-viz Darwin’s conclusions in the origin of species. The
claims and counter-claims between the theologists and scientists started long ago and still
continue till date. The unfortunate controversy has continued as the Genesis versus
Evolution debate which professor R. J. Berry summarized as: -
a) Those who are awed by scientific belief that the Bible has been disproved.
b) Those that cling to the inspiration of scripture and their interpretations of it and shut
their eyes to the fact that God’s work can be studied by scientific methods.

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 MODULE FIVE

ORIGIN OF MAN
Human Phylogeny
Introduction
As stated earlier on, human being (man) belongs to an order of mammals called primate.
Other primates include tarsiers, lorisers, lemurs, monkeys and apes (Gorilla, Chimpanzee).
Many of the features of this order are adaptations to life in a forest environment. Within
this order, primates are three groups of animals called anthropoids. These include the new
world monkeys (marmosets and spider monkeys) the old world monkeys (baboons and
prohoscis monkeys) and hominoids (apes and humans) humans and their ancestors are
more closely related to apes than other anthropoids.
Man belongs to the family hominidae (the fossil forms and modern human). Recent
evidence, based on comparative biochemistry has suggested that gorillas and chimpanzees
may have diverged from human stock as recently as 5 million years ago. Of particular
significance in the evolution of man is the development of an upright posture and increase
in brain size. Freedom of the hands from locomotion enabled them to be used for carrying
objects and manipulating the environment and all ritual activities. In addition an upright
posture which gave the hominoids increased height and ranges of vision have some
advantages for the primates. In addition to their ability to stand erect on two legs, they
enjoy the advantage of increasing brain size. This enables control and coordination to be
exercised as in special peculiarities, such as hunting, tool-making and speech. The course
of human evolution is remarkable in that gradual transmissions in physical features
(skeleton development) were supported by an accelerating development in social
behaviour. This process of becoming human is called hominization which is believed to be
influenced by:
i. The development of manipulative skill and speech.
ii. Changes in sexual behaviour allowing pair bonding and increased parental supervision
of children.
iii. The establishment of communal organization and social responsibility, arising from the
principle of food sharing.

Unit 1: Characteristics of the order Primates

Below are the features of the members of primate,
i. Possession of opposable thumb with grip for power and precision.
ii. Ability to rotate hand (fore limp) through 1800
iii. Eyes close together on face with parallel optical axis. (i.e. eyes are located in the front
part of the head).
iv. Possession of increased number of rods/ cones with own nerve cells.
v. Possession of reduced snout allowing flatter face.
vi. Possession of expanded area for cerebrum, ventral foramen magnum (i.e. enlarged
skull).
vii. Possession of increased sensory/motor areas, deep fission.

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Unit 2: Special Features of Man
Human beings enjoy some of the following advantages over and above other primates.
(i) Humans alone have developed spoken and written languages which are used to
communicate information not just about the physical world but to formulate abstract
concepts of arts, science, philosophy and religion.
(ii) Development of social behaviour to a greater extent than any other species. This was
intimately linked with the development of culture categorized by:
a) Establishment of the family (one partner or many wives)
b) Prolonged childhood during which time children could acquire the prevailing culture.
c) Increased use of speech for communication.
d) Development of the concepts of a home base and food sharing.
e) Increased cooperation in food-gathering enterprises
f) Division of labour by age and sex with older males hunting in bands to increase
efficiency of hunting and women staying together to ‘educate’ children and gain
protection from danger
g) Stabilization of a broader social structure where the dominance hierarchy was placed
by kinship and prohibition of incest.
h) Use of simple tools and eventually the manufacture of complex tools.
i) Use of fire for cracking rocks, hardening wood, cooking food, and for defence against
animals.
j) Development of folk wisdom, art, religion, philosophy, science and technology.
(iii) While humans share many aspects of behaviour with other primates and non-primates,
they are very unique in terms of art, religion and free-will. Humans are known for carving
of wood, ivory, painting. Religiously, it is only humans that have religion and free-will to
do things accordingly

Unit 3: Conceptions on the Origin of Man

The issue of the origin of man in line with the origin of life still remains a controversial
issue among different groups of people. This is because there are a number of rival
propositions and counterclaims on how man actually originated. For instance the Yoruba in
Nigeria believe that God is the original creator of heavens and the earth with all that dwell
in them. It is on the basis of this belief that the whole superstructure of the Yoruba believes
rests. According to the Yoruba tradition, as documented by Idiom (1962), some creatures
that form the nucleus of the human occupation of the earth had been in existence even
earlier than the earth. Traditionally, Yoruba also believe in “Olodumare”, “Orisanla”
“Orunmila” etc. Orisa-nla was regarded as the minister in charge of creation of the earth
and later created humans from the clay or dust of the earth. The duty of Orisa-nla was to
create a life-less human, while God will breathe in to the creative and thus, complete the
creation of human being. The office of the creator gave the Orisa-nla the freedom of
creating at will, human figures, perfect or defective, or whatever colour he wants them to
be. Thus, the hunch-back, the cripple, the albino, all are special works of his prerogative or
more often than not displeasure. Thus, to Yoruba, variation among human beings was due
to the pleasure or displeasure of Orisa-nla. Other people from different parts of the world
have their own way of looking at the origin of man. The Memphis in Egypt, the Shilluck of
the upper Nile, the people of Rwandan kingdom in Central Africa, from the Republic of
Benin believe God (whom they call different names) mould clay into human beings.
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Abaluyia of Karimido believed that the world was created in stages. According to them,
the creation took six days, God rested on the seventh day. Chinese legends gave the name
of the first man created by God as Panku. He was as big as four ordinary men put together.
It was this creature who separated the heaven from the earth with stone. He carved out
spaces for the moon, sun, stars. He dug valleys and made mountains on earth. When he
died, his remains formed five mountains in China. His breath became wind, his voice
became thunder, his bone became metal. Lastly, insects which stuck to his body became
human beings.
The theory of the special creation approached the origin of man from the religious points
of view. The holy Qur’an and the holy Bible share the same view about the origin of man.
The main point of the two religions has to do with spontaneous creation by God as we see
them.
Unit 4: Controversy Surrounding the Theory of Human Evolution
The theory of organic evolution as discussed in the previous units opposes the theory of
special creation which was proposed by spontaneous creation. With all the evidences
discussed in favour of theory of organic evolution, the proposition of the special creation
may not hold water. For example if man were created in God’s image what is God’s image.
Is God black or a white or mulatto? Is he a cripple man or hunch-back? Is he tall or short?
The controversy about the theory of evolution as it relates to origin of man had been on for
a long time. For example it was Charles Darwin’s work on the origin of species that
sparked off the controversy in the year 1859. The issue had been that of belief versus
hypotheses. For example, White (1960) in assessing the reason for religion/science conflict
over Darwin’s work noted that:
i) Darwin’s theory casts serious aspersion upon the creation story in the book of genesis.
ii) Its logical consequences threatened the belief that man was made in God’s image.
iii) Its acceptance rendered the doctrine of the fall of man unacceptable.

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 MODULE SIX
MAN AND NATURE
Introduction
Human beings live in the realm of nature; they are constantly surrounded by it and interact
with it. The most intimate part of nature in relation to man is the biosphere, the thin
envelope embracing the earth, its soil cover, and everything else that is alive. Our
environment, although outside us, has within us not only its image, as something both
actually and imaginatively reflected, but also its material energy and information channels
and processes. This presence of nature in an ideal, materialized, energy and information
form in man's self is so organic that when these external natural principles disappear, man
himself disappears from life. If we lose nature's image, we lose our life.

Unit 1: Man's Influence on Nature

Man is not only a dweller in nature, he also transforms it. From the very beginning of his
existence, and with increasing intensity human society has adapted environing nature and
made all kinds of incursions into it. An enormous amount of human labour has been spent
on transforming nature. Humanity converts nature's wealth into the means of the cultural
and historical life of society. Man has subdued and disciplined electricity and compelled it
to serve the interests of society. Not only has man transferred various species of plants and
animals to different climatic conditions; he has also changed the shape and climate of his
habitation and transformed plants and animals. If we were to strip the geographical
environment of the properties created by the labour of many generations, contemporary
society would be unable to exist in such primeval conditions.

Unit 2: Man and his Environment

Our body is a fragment of the cosmos, arranged in a very special way, but obeying the
same laws as the rest of the world. It is made up of the same elements as its physical
ambience. Moreover, man is functionally related to his environment. Each is adjusted to
the other in such a way that one could say the environment is the lock and man the key.
The surface of the earth presents a set of physical and chemical conditions which are
exceptional in the universe and eminently suited to our existence. Our planet retains about
it an atmosphere dense enough for living creatures to breathe the oxygen they need even on
high mountains. This same atmosphere protects plants and animals from cold and from the
harmful rays of the sun. And the attraction the earth exercises on all bodies makes us
adhere to its soil in the degree necessary to our mode of life.
Our environment is facing a lot of challenges in the area of degradation in the name of
development. As the population is rapidly increasing, so also the need for additional food
and shelter. Today, trees, rocks and other natural artifacts are destroyed to pave way for
buildings and other developmental projects thus changing the ecological balance of the
environment. Cutting of the trees promote desert encroachment and reduction in the
supply of oxygen (obtained from the trees) which humans and other animals need for
breathing and survival generally. The trees that are cut serve as fuel in some of our towns
and villages for cooking and for the cottage industries. Burning of the wood causes the
emission of dense smoke which wafts into the atmosphere thereby weakening the ozone
layer which in turn causes global warming. Another example of environmental
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degradation is the increase in the number of vehicles in our towns and villages. People and
vehicles are competing for space. The vehicles emit carbon monoxide as waste product.
Carbon monoxide is very poisonous to humans and also harmful to the environment.
Many of our industries emits large volume of this gas and together with that obtained from
the vehicles contributes to global warming which is currently a global phenomenon.
Environmental degradation is also responsible for climate change. For example, in the
arctic region where the people live in ice logged areas, the ice is rapidly melting thereby
changing the ecology of the region. The ice that melts finds its way to the oceans, seas,
rivers etc. thereby causing mass flooding in areas close to them example was the
devastating flooding of River Rima in Sokoto State of Nigeria in 2010. One of the effects
of global warming is the “drying” of the rivers, seas etc. for example, the famous Lake
Chad is drying rapidly thereby endangering the habitat and also depriving the people of the
area their main source of income, as many of them are fishermen who rely solely on the
lake. It therefore become a collective responsibility for all to join hands in saving the
environment from further dangers if we plan to live in it for a long time to come.

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 MODULE SEVEN
SCIENTIFIC METHOD
Introduction
Scientific method is the process by which scientists, collectively and over time, endeavor
to construct an accurate (that is, reliable, consistent and non-arbitrary) representation of the
world. Recognizing that personal and cultural beliefs influence both our perceptions and
our interpretations of natural phenomena, we aim through the use of standard procedures
and criteria to minimize those influences when developing a theory. As a famous scientist
once said, "Smart people (like smart lawyers) can come up with very good explanations for
mistaken points of view." In summary, the scientific method attempts to minimize the
influence of bias or prejudice in the experimenter when testing a hypothesis or a theory.

Unit 1: Steps in Scientific Method

1. Observation and description of a phenomenon or group of phenomena.
2. Formulation of a hypothesis to explain the phenomena. In physics, the hypothesis often
takes the form of a causal mechanism or a mathematical relation.
3. Use of the hypothesis to predict the existence of other phenomena, or to predict
quantitatively the results of new observations.
4. Performance of experimental tests of the predictions by several independent
experimenters and properly performed experiments.
If the experiments bear out the hypothesis it may come to be regarded as a theory or law of
nature (more on the concepts of hypothesis, model, theory and law below). If the
experiments do not bear out the hypothesis, it must be rejected or modified. What is key in
the description of the scientific method just given is the predictive power (the ability to get
more out of the theory than you put in; see Barrow, 1991) of the hypothesis or theory, as
tested by experiment. It is often said in science that theories can never be proved; only
disproved. There is always the possibility that a new observation or a new experiment will
conflict with a long-standing theory.

Unit 2: Common Mistakes in Applying the Scientific Method

As stated earlier, the scientific method attempts to minimize the influence of the scientist's
bias on the outcome of an experiment. That is, when testing a hypothesis or a theory, the
scientist may have a preference for one outcome or another, and it is important that this
preference not bias the results or their interpretation.

1. The most fundamental error is to mistake the hypothesis for an explanation of a

phenomenon, without performing experimental tests. Sometimes "common sense"
and "logic" tempt us into believing that no test is needed. There are numerous
examples of this, dating from the Greek philosophers to the present day.
2. Another common mistake is to ignore or rule out data which do not support the
hypothesis. Ideally, the experimenter is open to the possibility that the hypothesis is
correct or incorrect. Sometimes, however, a scientist may have a strong belief that
the hypothesis is true (or false), or feels internal or external pressure to get a
specific result. In that case, there may be a psychological tendency to find
"something wrong", such as systematic effects, with data which do not support the
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 scientist's expectations, while data which do agree with those expectations may not
be checked as carefully. The lesson is that all data must be handled in the same
way.
3. Another common mistake arises from the failure to estimate quantitatively
systematic errors (and all errors). There are many examples of discoveries which
were missed by experimenters whose data contained a new phenomenon, but who
explained it away as a systematic background. Conversely, there are many
examples of alleged "new discoveries" which later proved to be due to systematic
errors not accounted for by the "discoverers."

In a field where there is active experimentation and open communication among members
of the scientific community, the biases of individuals or groups may be cancelled out,
because experimental tests are repeated by different scientists who may have different
biases. In addition, different types of experimental setups have different sources of
systematic errors. Over a period spanning a variety of experimental tests (usually at least
several years), a consensus develops in the community as to which experimental results
have stood the test of time.

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 MODULE EIGHT
RENEWABLE AND NON-RENEWABLE RESOURCES
Unit 1: Renewable Resources
Natural resources, called renewable resources, are replaced by natural processes and forces
persistent in the natural environment. There are intermittent and reoccurring renewables,
and recyclable materials, which are utilized during a cycle across a certain amount of time,
and can be harnessed for any number of cycles. The production of goods and services by
manufacturing products in economic systems creates many types of waste during
production and after the consumer has made use of it. The material is then incinerated,
buried in a landfill or recycled for reuse. Recycling turns materials of value that would
otherwise become waste into valuable resources again.
The natural environment, with soil, water, forests, plants and animals are all renewable
resources, as long as they are adequately monitored, protected and conserved. Sustainable
agriculture is the cultivation of plant materials in a manner that preserves plant and animal
ecosystems over the long term. The overfishing of the oceans is one example of where an
industry practice or method can threaten an ecosystem, endanger species and possibly even
determine whether or not a fishery is sustainable for use by humans. An unregulated
industry practice or method can lead to complete resource depletion.

The renewable energy from the sun, wind, wave, biomass and geothermal energies are
based on renewable resources. Renewable resources such as the movement of water
(hydropower, tidal power and wave power), wind and radiant energy from geothermal heat
(used for geothermal power) and solar energy (used for solar power) are practically infinite
and cannot be depleted, unlike their non-renewable counterparts, which are likely to run
out if not used sparingly. The potential wave energy on coastlines can provide 1/5 of world
demand. Hydroelectric power can supply 1/3 of our total energy global needs. Geothermal
energy can provide 1.5 more times the energy we need. There is enough wind to power the
planet 30 times over; wind power could power all of humanity's needs alone. Solar
currently supplies only 0.1% of our world energy needs, but there is enough out there to
power humanity's needs 4,000 times over, the entire global projected energy demand by
2050.

Renewable energy and energy efficiency are no longer niche sectors that are promoted
only by governments and environmentalists. The increasing levels of investment and that
more of the capital is from conventional financial actors, both suggest that sustainable
energy has become mainstream and the future of energy production, as non-renewable
resources decline. This is reinforced by climate change concerns, nuclear dangers and
accumulating radioactive waste, high oil prices, peak oil and increasing government
support for renewable energy. These factors are commercializing renewable energy,
enlarging the market and growing demand, the adoption of new products to replace
obsolete technology and the conversion of existing infrastructure to a renewable standard.

Unit 2: Non-Renewable Resource

A non-renewable resource is made up of mostly dead animal skin and/or remains of plant.
The skin then turns into a resource such as oil. Also considered non-renewable are
resources that are consumed much faster than nature can create them. Fossil fuels (such as
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coal, petroleum, and natural gas), nuclear power (uranium) and certain aquifers are
examples. Metal ores are prime examples of non-renewable resources. In contrast,
resources such as timber (when harvested sustainably) and wind (used to power energy
conversion systems) are considered renewable natural resources; renewable resources are
replaced by natural processes and forces persistent in the natural environment. There are
intermittent and reoccurring renewable, and recyclable materials, which are utilized during
a cycle across a certain amount of time, and can be harnessed for any number of cycles.
The production of goods and services by manufacturing products in economic systems
creates many types of waste during production and after the consumer has made use of it.
The material is then incinerated, buried in a landfill or recycled for reuse. Recycling turns
materials of value that would otherwise become waste into valuable resources again.

Fossil fuel
Fossil fuels include coal, petroleum, natural gas, oil shales, bitumens, tar sands, and heavy
oils. All contain carbon and were formed as a result of geologic processes acting on the
remains of organic matter produced by photosynthesis, a process that began in the Archean
Eon (4.0 billion to 2.5 billion years ago). Most carbonaceous material occurring before
the Devonian Period (419.2 million to 358.9 million years ago) was derived
from algae and bacteria, whereas most carbonaceous material occurring during and after
that interval was derived from plants.
All fossil fuels can be burned in air or with oxygen derived from air to provide heat. This
heat may be employed directly, as in the case of home furnaces, or used to
produce steam to drive generators that can supply electricity. In still other cases—for
example, gas turbines used in jet aircraft—the heat yielded by burning a fossil fuel serves
to increase both the pressure and the temperature of the combustion products to furnish
motive power.
Since the beginning of the Industrial Revolution in Great Britain in the second half of the
18th century, fossil fuels have been consumed at an ever-increasing rate. Today
they supply more than 80 percent of all the energy consumed by the industrially developed
countries of the world. Although new deposits continue to be discovered, the reserves of
the principal fossil fuels remaining on Earth are limited. The amounts of fossil fuels that
can be recovered economically are difficult to estimate, largely because of changing rates
of consumption and future value as well as technological developments. Advances
in technology—such as hydraulic fracturing (fracking), rotary drilling, and directional
drilling—have made it possible to extract smaller and difficult-to-obtain deposits of fossil
fuels at a reasonable cost, thereby increasing the amount of recoverable material. In
addition, as recoverable supplies of conventional (light-to-medium) oil became depleted,
some petroleum-producing companies shifted to extracting heavy oil, as well as liquid
petroleum pulled from tar sands and oil shales.
One of the main by-products of fossil fuel combustion is carbon dioxide (CO2). The ever-
increasing use of fossil fuels in industry, transportation, and construction has added large
amounts of CO2 to Earth’s atmosphere. Atmospheric CO2 concentrations fluctuated
between 275 and 290 parts per million by volume (ppmv) of dry air between 1000 CE and
the late 18th century but increased to 316 ppmv by 1959 and rose to 412 ppmv in 2018.
CO2 behaves as a greenhouse gas—that is, it absorbs infrared radiation (net heat energy)
emitted from Earth’s surface and reradiates it back to the surface. Thus, the substantial
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CO2 increase in the atmosphere is a major contributing factor to human-induced global
warming. Methane (CH4), another potent greenhouse gas, is the chief constituent of natural
gas, and CH4 concentrations in Earth’s atmosphere rose from 722 parts per billion (ppb)
before 1750 to 1,859 ppb by 2018. To counter worries over rising greenhouse gas
concentrations and to diversify their energy mix, many countries have sought to reduce
their dependence on fossil fuels by developing sources of renewable energy (such
as wind, solar, hydroelectric, tidal, geothermal, and biofuels) while at the same time
increasing the mechanical efficiency of engines and other technologies that rely on fossil
fuels.

Radioactive fuel
Nuclear fuel is material used in nuclear power stations to produce heat to power turbines.
Heat is created when nuclear fuel undergoes nuclear fission. Most nuclear fuels contain
heavy fissile actinide elements that are capable of undergoing and sustaining nuclear
fission. The three most relevant fissile isotopes are Uranium-233, Uranium-
235 and Plutonium-239. When the unstable nuclei of these atoms are hit by a slow-
moving neutron, they split, creating two daughter nuclei and two or three more neutrons.
These neutrons then go on to split more nuclei. This creates a self-sustaining chain
reaction that is controlled in a nuclear reactor, or uncontrolled in a nuclear weapon. The
processes involved in mining, refining, purifying, using, and disposing of nuclear fuel are
collectively known as the nuclear fuel cycle. Not all types of nuclear fuels create power
from nuclear fission; plutonium-238 and some other elements are used to produce small
amounts of nuclear power by radioactive decay in radioisotope thermoelectric
generators and other types of atomic batteries. Nuclear fuel has the highest energy
density of all practical fuel sources.
Generating electricity using nuclear reactors carries high risk but offers large rewards. In
operation, a very small amount of nuclear fuel will consistently generate a very large
amount of electricity and generate very little polluting material. However, the financial
costs of building and decommissioning a nuclear power station are very large, and the
waste produced will remain radioactive - hazardous to humans and the environment - for
thousands of years.
Advantages Disadvantages
Produces no polluting gases. Waste is radioactive and safe disposal is very
difficult and expensive.
Does not contribute to global Local thermal pollution from wastewater
warming. affects marine life.
Very low fuel costs. Large-scale accidents can be catastrophic.
Low fuel quantity reduces mining and Public perception of nuclear power is negative.
transportation effects on environment.
High technology research required Costs of building and safely decommissioning
benefits other industries. are very high.
Power station has very long lifetime. Cannot react quickly to changes in electricity
demand.

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 MODULE NINE
CONCEPT OF ENERGY
Introduction
Energy is defined as the ability or capacity to do work. We can also define energy as the
potential or capacity to move matter. To a scientist, this definition means that the energy of
anything is related to its ability to move an object some distance. All forms of energy are
capable of doing work (that is of exerting a force over a distance). Energy is divided into
potential i.e. energy due to position, and kinetic (energy produced by a moving object).
The most obvious form of energy is kinetic energy (or energy of matter in motions). There
are other forms of energy, though, where there is no obvious motion, but where there is a
potential for motion.
Unit 1: Forms of Energy
As stated earlier on, energy exists in different forms. The two main forms of energy are
potential energy and kinetic energy. Energy may also be electric, chemical, radiant, nuclear
or other forms. A battery is essentially a store of energy because it has chemical substances
with the potential to move matter. Imagine an electric car which has a battery pack that
drives the car. The battery in the pack contains chemical substances that can react to
produce electric current, which goes into the electric motor. The electric motor moves the
car. A car in motion has energy as a result of that motion. A battery is said to contain
‘chemical energy’ because the chemical substances in it has the potential to move matter,
irrespective of their being used for this purpose or not. Heat is another form of energy.
When heat passes into a substance such as air, bits of matter (air molecules) begin to move
faster. The motion is not that of ordinary-size pieces of matter, rather that of extremely
small bits of matter or molecules. Heat is the kinetic energy of moving molecules. Light is
another form of energy. When a material absorbs light, it becomes hotter. The hotness is
due to extremely small bits of matter (molecules of the material) moving faster than they
were before the material absorbed the light. Light then has the potential to move matter and
is a form of energy. This indicates that all forms of energy are associated with motion. In
summary, energy comes in various forms including chemical, heat and light. It is possible
to change one form of energy into another.
Different forms of energy have been mentioned. Below are the explanations of
different forms of energy:
i) Radiant energy: This comes from the sun (solar energy) and is earth’s primary energy
source. Solar energy heats the atmosphere and earth’s surface; stimulates the growth of
regulation through the process of photosynthesis, and influences global climate patterns.
ii) Thermal energy: This is the energy associated with the random motion of atoms and
molecules. The more vigorous the motion of the atoms and molecules in a sample of
matter, the hotter the sample and the greater its thermal energy. Generally, thermal energy
can be calculated from temperature measurements.
iii) Chemical energy: This is stored within the structural units of chemical substances. Its
quantity is determined by the type and arrangement of atoms in the substance being
considered. When substances participate in chemical reactions, chemical energy is
released, stored or converted to other forms of energy.
iv) Energy is also available by virtue of an object’s position: This form of energy is called
potential energy. For example by virtue of its altitude, a rock at the top of a hill has more
potential energy and will make a bigger splash in the water below than a similar rock
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located pathway down. Hence, potential energy can also be expressed in terms of the
energy possessed by an object in an elevated position. Chemical energy can be regarded as
a form of potential energy because it is associated with the relative positions and
arrangements of atoms within a substance.
Unit 2: Man’s Energy Needs and Resources.
The ultimate source of energy on earth to man is the sun, (solar energy). The sun is
constantly radiating light on the earth surface. A portion of this light energy falls on earth,
and some of it is used by plant to convert carbon dioxide and water into various energy
storing compounds, via a process known as photosynthesis. During this process water and
carbon dioxide (from air) combined using energy to produce glucose and oxygen. When
such plants are eaten, the chemical energy stored in them (glucose) is transferred into and
used by man for his daily activities to produce energy thus reversing the above process of
photosynthesis. Carbon dioxide + water + energy glucose + oxygen (sunlight). Glucose +
oxygen + Carbon dioxide + water + energy.
The chemical energy stored in the food eaten by man is converted into heat energy after
being subjected to series of physiological processes in man’s body. The energy is made
available in its various forms depending on man’s need at any given point in time. Much of
the energy available on earth has been collected by plants during photosynthesis. Man and
indeed all animals ultimately rely on plants for food energy. Ultimately, the plants and the
sun provide man with the food energy we need. Having examined man’s basic source of
energy the next question is why do man need energy? In the next section of this unit, you
will learn about basic reasons for man’s quest for energy.
Unit 3: Uses of Energy to Man
Some common examples of the use of energy by man include:
1. Synthesis of materials for growth and repairs for instance protein synthesis.
2. Active transport of materials in and out of cells against diffusion gradients, for
example the sodium-potassium pump.
3. Electrical transmission of nerve impulses
4. Heat energy released from respiration is used to maintain constant body
temperature in man.
5. Mechanical contraction and relaxation of muscles.
However, human civilization consumes more than food energy. We use energy to heat our
homes, to power our cars, and to drive technology. Commerce, industries, computers are
other vital areas where energy has been found very useful.
Unit 4: Energy on Earth
As stated earlier on, the sun provides the basic and ultimate source of energy to man.
However the three largest sources of the energy consumed by man are petroleum, coal
and natural gas. These are all “fossil fuels’. The fossil fuels were formed million years
ago, when aquatic plants and animals were buried and compressed by layers of sediments
at the bottom of swamps and seas. Here again we can trace the origin of energy back to
plants, and therefore the sun. Another large source of energy is hydroelectric to plant but
can be traced back to the sun. Hydroelectric power is electric power generated by river
water flowing through a turbine. This energy of the river comes from the sun. The sun’s
warmth evaporates water and this water vapour later condenses as rain which later flows to
the rivers. Nuclear energy, another source of energy on earth, does not originate from the

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sun though Uranium, which is the source of nuclear energy, has been present on earth since
the solar system first formed about five million years ago.
Sources of Energy
There are a number of sources from which man obtains energy to provide heat, light, and
power. These sources can be categorized as:
i) Basic or natural source
ii) Other sources/non-renewable sources.
Let us now look at these two sources of man’s energy needs in more details.
Basic or natural source of energy
Substantial amount of energy is obtained from such natural sources as wood, water, wind
and tide. Some of those natural products have provided man with useful means of
obtaining energy.
i) Wood: provides a major source of energy today in different parts of the world where
other fuels are not available or their prices is unaffordable. For instance, in Brazil, wood
still provides a greater percentage of the nation’s non-fuel energy. Nigeria however is not
an exception to this, especially nowadays that the prices of kerosene and other fuels are
almost out-of-reach of common man. Wood is commonly used for cooking and other
domestic purposes as a means of obtaining energy in both rural and urban cities in Nigeria.
ii) Water: water is a good source of energy, though, attention is being directed at it
presently, as it is estimated to provide less than five percent of the worlds energy
requirements. Among the limitations placed on water power are the fact that food from
river valleys is more valuable than power obtained from damming the valley as a reservoir
in arid lands. Water is essential for farming; examples are the lower Ogun irrigation
scheme at Iseyin and a number of other river basin development authorities scattered all
over Nigeria.
iii) Wind: The wind contains tremendous amount of energy, but it is intermittent and
diffuse. Wind mills are usually more expensive relative to the energy delivered. Interest in
energy from water, wood and wind mill increases as fossil fuel costs rise and storage is
improved. It is used in countries like France. This form of energy is yet to be fully
developed and utilized in Nigeria.
iv) Geothermal energy: This flows from the hot interior part of the earth to the surface
where it is lost by radiation into space. Studies have been carried out on how this could be
tapped as useful source of energy. This has been used very successfully in some parts of
the world to generate energy and power. This form of energy is in use in places such as
Netherlands and North America (for guiding grams in pumping water). In the West Indies
it is used for grinding sugar cane. Other nations where this form of energy has been
successfully utilized include Italy, Iceland, California and so on.
v) Tidal energy: There is a great amount of energy in the tides, but the oceans have been a
difficult energy source to harness. This energy comes from the energy of rotation of the
earth. Even though only a small fraction of the tidal power can be tapped, this source of
energy is expected to be put in greater use in the near future. All these energy sources are
classified as recurring energy sources, because they are continuously being created from
primary sources.
– End –

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