biol115_2014_lecture 2_science & evolution.pdf

Biol115The Thread of Life

Lecture 2

1. This thing called science.

2. Evolution.

"The most beautiful experience we can have is the

mysterious - the fundamental emotion which stands at the

cradle of true art and true science.“Albert Einstein, 1931

Principles of Biology

Chapter “Practicing Biology”

Biol115_2014_Lecture 2 2

Objectives

• Describe the science of biology.

• Describe the scientific methodology as applied to biology.

• Explain the significance of communication and collaboration among members of the global scientific community.

• Understand how to effectively and efficiently read a published scientific paper.

• Key Terms: control variable, controlled experiment, data, deductive reasoning, dependent variable, hypothesis, independent variable, inductive reasoning, observation, science, scientific inquiry, theory.


ScienceUnderstanding Science - http://undsci.berkeley.edu/index.php


The word science is derived from Latin and means ‘to know’.

Scientific inquiry is the search for information and explanation. Investigation of the natural world by natural methods

There are two main types of scientific inquiry: Discovery science (describing nature). Hypothesis-based science (explaining nature).

Data (singular datum) are a collection of observations. They may be qualitative or quantitative.

The scientific process

Observations

Hypotheses

Theories


Hypotheses and Theories


An hypothesis is a tentative answer to a well-framed question, which leads to predictions.

A hypothesis must be testable and falsifiable.

In science, observations and experimental results must be repeatable.

Theories (e.g. Atomic theory, Big Bang theory, Evolutionary theory) are broader in scope and

supported by a large body of evidence.

Hypotheses, theories and laws are all scientific explanations that differ in breadth — not in

level of support.

If we are uncritical we shall always find what we want: we shall look for, and find, confirmations, and we shall look away

from, and not see, whatever might be dangerous to our pet theories.

Sir Karl Popper, 1957

Science is a way of trying not to fool yourself. The first principle is that you must not fool yourself, and you are the

easiest person to fool.

Richard Feynman, 1964

The scientific method

• Ask a question

• Develop a falsifiable hypothesis

• Test the hypothesis

• Analyze data

• Support or refute hypothesis

- Refine hypothesis


Deductive reasoning

uses general principles

to deduce the answer

to specific questions.

Inductive reasoning

uses a series of

examples from which to

draw general

conclusions.

Deductive versus inductive reasoning


Science and society


Science and society

• Scientific inquiry has provided us with an in-depth understanding of us and the world around us.

• More than ever before, society is driven by science and technology.

• Is the gap (in scientific understanding) between scientists and the lay public widening?


Perceptions of scientific concepts


Australian Academy of Science, 2013

Around 6 in 10 Australians know it takes one year for the Earth

to travel around the sun

The proportion that gave the correct answer fell from 61% to 59% since 2010.

30% of Australians think that it takes one day for the Earth to orbit the sun.

28

30

1

1

2

2

61

59

8

9

0 25 50 75 100

2010

2013

One day One week One month One year Not Sure

Q: How long does it take for the Earth to go around the Sun?

Q: How long does it

take for the Earth to

go around the Sun?

1 year: 59%

1 day: 30%

Common vs. scientific language

Word Common

language

Scientific language

Law A rule that must be

abided

A generalisation about data; a

statement of relationships

between variables

Hypothesis An educated guess Conclusions based on prior

experience, background,

knowledge, observation and

logic. Possess explanatory

power.

Theory A hunch with little

evidentiary

support.

Broad explanations for a wide

variety of phenomena.

Supported by many lines of

evidence.Biol115_2014_Lecture 2 12

A science checklist

• Focuses on the natural world.

• Aims to explain the natural world.

• Uses testable ideas.

• Relies on evidence.

• Involves the scientific community.

• Leads to on-going research.

• Benefits from scientific behaviour.


Is astrology scientific?


Criteria Analysis

Focuses on the natural

world?

Astrology's basic premise is that heavenly bodies have influence over or are correlated with earthly events.

Aims to explain the natural

world?

Astrology uses a set of rules about the relative positions and movements of heavenly bodies to generate

predictions and explanations for events on Earth and human personality traits.

Uses testable ideas? Some expectations generated by astrology are so general that any outcome could be interpreted as fitting the

expectations; if treated this way, astrology is not testable.

Relies on evidence? Evidence did not support the validity of astrological ideas. Astrology has not changed its ideas in response to

contradictory evidence.

Involves the scientific

community?

Sharing one's findings and critically evaluating the results of others are not integral parts of practicing

astrology. Astrological publications are not usually peer-reviewed or published in places where they will be

critically scrutinized by the scientific community.

Leads to ongoing

research?

Scientific studies involving astrology have stopped after attempting and failing to establish the validity of

astrological ideas. So far, there are no documented cases of astrology contributing to a new scientific

discovery.

Researchers behave

scientifically?

Astrologers do not seem to rigorously examine the astrological ideas they accept. As reflected by the minimal

level of research in the field, they rarely try to test their arguments in fair ways. In addition, the astrological

community largely ignores evidence that contradicts its ideas.

Carlson, S. 1985. A double-blind test of astrology. Nature 318:419-425.

Science communication

• Science is collaborative by nature.

• Scientific ideas and discoveries are discussed at scientific conferences, grant applications and through scientific publications.

• Scientific ideas have to be peer-reviewed before they are published or funded.

• Many fields of science are moving toward other publication models, including websites such as arXiv (arxiv.org). Billions of pieces of data are now stored on publically-accessible databases such as the National Center for Biotechnology Information (ncbi.nlm.nih.gov) and the Dryad data depository (datadryad.org).


http://www.arxiv.org/

http://www.ncbi.nlm.nih.gov/

http://datadryad.org/

Abstract: A brief overview of the paper.

Introduction: Overview of the background and approach.

Materials and Methods: Describes what was done.

Results: Description of data, analyses, figures and tables.

Discussion: Interpret results, refine hypotheses.

Components of a scientific paper

(research articles)


Peer-review: a self-check mechanism• Scientific discoveries are reviewed by other scientists to ensure the validity of the

inquiry and conclusions.

• Cold fusion: Stanley Pons and Martin Fleischmann (University of Utah) reported

that they performed nuclear fusion in a simple electrochemical cell.

• Cloning: Woo Suk Hwang (Seoul National University) claimed that his team

cloned human embryos from stem cells.


http://www.time.com/time/magazine/0,9263,7601931108,00.html

A DNA fingerprinting graph from one of Woo Suk

Hwang's retracted papers. Careful scrutiny of the peaks

in such graphs helped identify his fraud.

Popular press and scientific accuracy

• Newspapers and popular magazine are commercial enterprises and rely on enhancing sales.

• The need for (false) balance:• (1988-2002) 52.6% of mainstream U.S. newspapers

‘balanced’ anthropogenic climate warming with a skepticalview.

• (1993-2003) 0% of 928 scientific journal articles disagreed with anthropogenic climate warming!


http://image3.examiner.com/images/blog/EXID19821/images/climategate.jpg

What science does not do

• Science does not make moral judgements.• Is euthanasia right?

• Science doesn’t make aesthetic judgements.

• Science doesn’t tell us how to use scientific knowledge.• E.g. science tell us how to do genetic engineering but not whether it

should be used to cure diseases

• Science does not draw conclusions about supernatural explanations.• Science cannot support or contradict the existence of supernatural

entities. It deals only with natural phenomena.


Summary

By now, you should know that ….

• Science is a human endeavour to learn about the natural world using

natural processes.

• Science has deepened our understanding of the world and about us.

• Science plays a significant role in our lives.

• Scientific literacy is essential: political and societal policies require an

understanding of scientific facts. However, policies cannot be developed by

scientists alone, but everyone concerned.

• Misrepresentation of science is common.


Biol 115The Thread of Life

Evolution

“There is a grandeur in this view of life ... [in which]

endless forms most beautiful and most wonderful have

been, and are being, evolved”~Charles Darwin,

The Origin of Species

Principles of Biology

Chapter ‘Evolution and Life on Earth’

Chapter ‘Introduction to Evolution’

Chapter ‘The Darwinian Revolution’


Objectives

• Explain how Darwin's research and observations of the natural world affected his ideas about species.

• Describe the historical academic context of Darwin's publications.

• Describe Darwin's arguments for the theory of natural selection to explain descent with modification.

• Generalize the effect of Darwin's ideas on science and society.

• Key Terms: descent with modification, evolution, natural selection, fitness


Insert Fig. 22-2 P455

The evolution of evolutionary theory

24Biol115_2014_Lecture 2

“Nothing in biology makes sense except in the light of evolution”

Theodosius Dobzhansky.

Classification of organisms established biological relationships

In the 1700s, the Swedish taxonomist Carl Linnaeus (1701-1778) developed a new system that classified organisms into nested hierarchies based on their similar gross morphological characteristics, including their external shape, structure, colour, pattern, and internal features, such as bones and organs. Linnaeus's hierarchical classification and consistent use of binomial nomenclature remain in use today. Linnaeus published the final edition of his classification system (Systema Naturae) in 1758.


Of endless forms most beautiful


Descent with modification

Influences on Darwin

• Thomas Malthus

A limit to how many individuals can survive on limited

resources (originally proposed for economies of human

populations).

• Charles Lyell

Geological formations occurred over long periods of time


• Darwinian evolution is driven

by natural selection, leading

to “Descent with

Modification.”

• Phylogenetic trees are used

to describe evolutionary

relationships among taxa.

• Evolution explains both the

unity and diversity of life

and influences all levels of

biological organization.


• Natural selection are ‘internal’ or ‘external’ factors that affect

survival or reproductive ability.

• Populations and individuals which survive to reproduce are

considered to be “fit” and “adapted”.

• Note that individuals do not evolve; populations evolve over

time

• Natural selection can only increase or decrease heritable

traits in a population

Evolution through natural selection: a summary


Observations on natural

selection:

Some heritable traits are favored

over others.

Inference of outcomes of

natural selection:

Favored traits accumulate and

lead to changes through time.


Evolution is supported by an overwhelming amount of scientific evidence


Four types of data that support evolution:

• Direct observation

• Fossil record

• Homology

• Biogeography

Influence of natural selection on beak depth of medium

ground finch (Geospiza fortis) on Daphne Major.

Observations of the beak depth of finches born in each time

period (boxes represent the average, and "whiskers" represent

the standard deviation). The red-shaded area represents a

severe drought that occurred during 1977. The dramatic shift in

beak depth represents a strong case of natural selection, which

resulted because bigger-beaked individuals could consume

larger seeds, and the smaller-beaked individuals shown on the

left could not crack these seeds open.

Evolution and Society

• Evolution is an ultimate unifying concept for biology.

• Descent of Man agitated the Church of England.

• Reverend Dr. Malcolm Brown, Director of Mission and Public Affairs of the Church of England, published an essay entitled "Good Religion Needs Good Science“ (2008).

• Some factions of religious fundamentalists still reject the idea that species evolve.

• In certain parts of the United States, the controversy shows no sign of abating as battles still rage over the teaching of evolution in schools.


Creationism and intelligent design

• Creationism refers to the religious belief in a supernatural deity or force that intervenes, or has intervened, directly in the physical world.

• 1920s: split in American Protestanism- “fundamentalist” and “modernist”.

• William Jennings Bryan: “Darwinism” had been the cause of German militarism as well as a threat to traditional religion and morality



• 1925 Scopes Monkey Trial in Dayton, TN.

• Many American states enacted laws that prevented the teaching of evolution in schools.

• “Creation science” arose on the national scene in the late 1960s as a counter to the reintroduction of evolution into the curriculum.



• ID is conspicuously absent from the scientific literature in

general.

• Two important components of ID: “irreducible complexity

(Michael Behe) ”, and “specified complexity (Dembski)”.

• Bacterial flagella: 42 proteins make up this organelle. In

Salmonella typhimurium, only 20 are universally required, and 18

of those have homologues that function in other biochemical

systems.


SummaryBy now, you should be able to …

1. Define evolution in biological systems.

2. Explain what Darwin meant by “descent with modification”.

3. List and explain Darwin’s observations and inferences about evolution.

5. Visualise evolutionary relationships in the form of ‘trees’.

6. Describe at least four lines of evidence for evolution by natural selection.

7. Understand that creation science and intelligent design are not alternatives to evolutionary theory.


biol115_2014_lecture 2_science & evolution.pdf

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