BIO 2 Lecture 1
WHAT IS SCIENCE?
READING: (CONCEPT 1.5)
“The word science is derived from a Latin
verb meaning ‘to know.’ Science is a way of
knowing.”
- Biology, 7th ed., Campbell and Reese
“Science is a body of empirical, theoretical,
and practical knowledge about the natural
world, produced by a global community of
researchers making use of scientific
methods, which emphasize the observation,
experimentation and explanation of real
world phenomena.”
- Wikipedia (2008)
Science is:
“1. The systematic observation of natural
events and conditions in order to discover facts
about them and to formulate laws and principles
based on these facts.
2. The organized body of knowledge that is
derived from such observations and that can be
verified or tested by further investigation.”
- Academic Press Dictionary of Science &
Technology
“Science … is the systematic and organized
inquiry into the natural world and its
phenomena. Science is about gaining a deeper
and often useful understanding of the world.”
- Multicultural History of Science page at
Vanderbilt University.
“As a practicing scientist, I share the credo of my
colleagues: I believe that a factual reality exists and
that science, though often in an obtuse and erratic
manner, can learn about it. Galileo was not shown the
instruments of torture in an abstract debate about
lunar motion. He had threatened the Church's
conventional argument for social and doctrinal stability:
the static world order with planets circling about a
central earth, priests subordinate to the Pope and
serfs to their lord. But the Church soon made its peace
with Galileo's cosmology. They had no choice; the earth
really does revolve around the sun.”
-Stephen J. Gould, The Mismeasure of Man
“Science alone of all the subjects contains
within itself the lesson of the danger of belief
in the infallibility of the greatest teachers in
the preceding generation . . .As a matter of
fact, I can also define science another way:
Science is the belief in the ignorance of
experts.”
-Richard Feynman, Nobel-prize-winning physicist
in The Pleasure of Finding Things Out
-Examples: Inquiry into Challenger disaster O-ring
failure; Conspiracy theories about the assassination of
President Kennedy
What Do these Definitions of
SCIENCE Have in Common?
1. The universe is real and its behavior has
regular patterns (“laws”) that can be
studied and modeled through science
2. Science is a method of learning about the
universe and its behavior
3. Science is a collection of facts about the
universe and how it behaves
4. Science is a collection of theories that
have predictive power concerning how the
universe will behave in the future
5. Science is progressive; it models the
universe and its behavior more and more
accurately over time
What is the
SCIENTIFIC METHOD?
“In hypothesis-based science, deduction
usually takes the form of predictions about
what outcomes of experiments or observations
we should expect if a particular hypothesis
(premise) is correct. We then test the
hypothesis by performing the experiment to
see whether the results are as predicted. The
deductive testing takes the form of “If ...
then” logic.”
- Biology, 7th ed., Campbell and Reese
“Scientific method refers to a body of
techniques for investigating phenomena, acquiring
new knowledge, or correcting and integrating
previous knowledge. To be termed scientific, a
method of inquiry must be based on gathering
observable, empirical and measurable evidence
subject to specific principles of reasoning. A
scientific method consists of the collection of
data through observation and experimentation,
and the formulation and testing of hypotheses.”
- http://en.wikipedia.org/wiki/Scientific_method
http://www.eas.slu.edu/People/RBHerrmann/Courses/EASA193F07/
Images/overview_scientific_method2.gif
The scientific method is … “The stumbling way
in which even the ablest of the scientists in
every generation have had to fight through
thickets of erroneous observations, misleading
generalizations, inadequate formulations, and
unconscious prejudice [that] is rarely
appreciated by those who obtain their
scientific knowledge from textbooks.”
-James Bryant Conant (1893-1978), Science
and Common Sense
The scientific method is a way of learning
about the universe that uncovers scientific
facts and helps scientists build better theories.
•
•
•
•
Begins with observations about the World and its
behavior
Develops testable hypotheses that might explain the
observations
Systematically eliminates hypotheses through
careful experimentation
Takes no prisoners
-Dr. Ruth Ballard
What are Scientific FACTS?
Scientific facts are statements about the
universe and its behavior that seem irrefutable
at the time they are accepted as such.
Scientific facts are discovered through a
process of careful and reproducible observations
and/or experiments that stand the test of time.
Example: “The Earth is a sphere, not flat.”
Although it certainly appears to the casual
observer that the Earth is flat, and people
believed for thousands of years that the Earth
was flat, the FACT is that the Earth is a sphere.
• Early sailors observed that the tops of
mountains and buildings come into view
above the horizon before objects nearer to
the ground
• Mariners sailed all the way
around the globe, always
going in one direction
• Newton’s Law of Gravity
provided a mechanism for
how a spherical Earth could
“work”
We’ve
photographed
it from space
We’ve orbited
around it in
space ships
What are Scientific THEORIES?
“A scientific theory is much broader in scope
than a hypothesis ... is general enough to spin
off many new specific hypotheses that can be
tested ... [and], compared to any one
hypothesis, is generally supported by a much
more massive body of evidence.”
- Biology, 7th ed., Campbell and Reese
“Example: “Evolutionary adaptations evolve by
natural selection.”
• All theories are NOT equally valid! Good
theories explain all (or most) of the facts
and make testable predictions that are
borne out by experimentation
• A better theory is one that explains more
facts and has more predictive power than
the former theory
• Thus, scientific theories can (and do)
change or get replaced over time, but in a
directed manner
Fact or Theory?
•
•
•
•
The Earth revolves around the Sun
Humans reproduce sexually
All crows are black
The DNA sequence of humans and
chimps is approximately 98% identical
• Humans and chimps evolved from a
common ancestor
Can a THEORY become a FACT?
YOU BET! Theories become facts when the
evidence supporting them becomes do
overwhelming that to refute them is basically
absurd …
Examples:
“The Earth is a sphere” used to be a theory. “The
Earth revolves around the Sun” used to be a
theory.
“Whales are mammals, not fish”, used to be a
theory ...
The Scientific Method at Work:
Disproving Abiogenesis
• Aristotle (384-322 BC)
proposed the idea of
spontaneous generation
or abiogenesis
• Abiogenesis postulates that living things
arise from nonliving matter
• The idea persisted for over 2,000 years
• In ancient times, the scientific method
was unknown and not systematically
practiced
• People based their beliefs on what they
saw around them but did not carefully
and reproducibly test their beliefs
• (Unfortunately, this is still true is some
segments of society today – e.g. dowsing,
flower whispering, astrology, coffee
ground readings, DNA activation healing,
etc., etc.)
• Example: In Egypt, the Nile flooded
every spring, leaving behind nutrientrich mud. Frogs were plentiful at this
time – much more so than in the dry
season.
• Therefore, people concluded that
muddy soil must give rise to frogs.
• Example: In parts of
Europe, medieval farmers
stored grain in barns with
thatched roofs. As these
roofs aged, they would leak,
causing the grain inside to
get moldy. Moldy grain, in
turn, attracted mice.
• Therefore, people
concluded that moldy grain
must give rise to mice.
Actual Abiogenesis Recipes
• Recipe for bees:
– Kill a young bull, and bury it in an upright
position so that its horns protrude from the
ground. After a month, a swarm of bees will
fly out of the corpse.
• Recipe for mice:
– Place a dirty shirt or some rags in an open
pot or barrel containing a few grains of
wheat or some wheat bran, and in 21 days,
mice will appear. There will be adult males
and females present, and they will be capable
of mating and reproducing more mice.
Testing Abiogenesis through
the Scientific Method
• Redi’s (1626-1697) Experiments:
Evidence against spontaneous generation:
1. Unsealed – maggots on meat (FLIES)
2. Sealed – no maggots on meat
3. Gauze – few maggots on gauze (NO FLIES)
• The results of Redi’s experiment disproved
the idea of spontaneous generation for
larger organisms, but people still thought
microscopic organisms like algae or bacteria
could arise that way …
• Lazzaro Spallanzani’s Experiments (1765)
• Critics said sealed vials did not allow enough air
for organisms to survive and that prolonged
heating destroyed “life force”
• Therefore, abiogenesis remained the theory of
the time
• By 1860, the debate had become so heated that
the Paris Academy of Sciences offered a prize
for any experiments that would help resolve
this conflict
• The prize was claimed in 1864 by Louis Pasteur,
as he published the results of an experiment
that disproved the hypothesis that abiogenesis
occurs in microscopic organisms
• Hypothesis: Microbes come from cells of
organisms on dust particles in the air; not
the air itself.
• Experiment:
– Pasteur put broth into several special Sshaped flasks
– Each flask was boiled and placed at
various locations
– S-shaped Flask
– Filled with broth
– The special shape was intended to trap
any dust particles containing bacteria
• Pasteur’s S-shaped flask kept microbes out but
let air in, proving that the lack of bacterial
growth was NOT the result of a lack of
sufficient air
• Disproved the abiogenesis of microbes and
supported the theory of biogenesis (life only
arises from other life forms)
• Since that time, all experiments that have
attempted to disprove biogenesis have failed,
which is why it is now so widely an accepted
scientific theory that it is accepted by most
scientists as FACT.