Evolution part 1

BIOLOGICAL EVOLUTION:
THE PROCESS

Wednesday, June 2, 2010

Wanting What You Can’t Have
•A Scientific Theory Can’t Give You:
• Theological or metaphysical truths
• An ethical or moral system
• The meaning of life !


Wanting What You Can’t Have
•A Scientific Theory Can’t Give You:
• Theological or metaphysical truths
• An ethical or moral system
• The meaning of life !
• A Good Scientiﬁc Theory Can:
• Reveal connections between seemingly disparate facts
• Motivate and guide a research program
• Predict new observations
• Answer one question and create two new ones


Biological
Evolution
Background and Basics


“Endless forms most
beautiful…”


24,000 Species of Orchids


The Wee Beasties


What is responsible
for all of this variety
in life forms?


Three Pre-Darwinian Beliefs
About Evolution
Special Creation

• Species created
independently. Unrelated to
each other
• Unchanging - created as
you see it right now
• Young Earth - 6000 years
old


About Evolution
Special Creation Random Assembly

• Species created • Random
each other • Changing
• Unchanging - created as • Species related but
you see it right now random variations
• Young Earth - 6000 years on ancestral forms
old


About Evolution
Special Creation Random Assembly

• Species created • Random
each other • Changing
• Unchanging - created as • Species related but
you see it right now random variations
• Young Earth - 6000 years on ancestral forms
old Lamark
• Evolution by necessity
• Acquired Characteristics

Random Generation of
Organisms is Mathematically
Implausible and Inconsistent
with Observed Order within
Ecosystems


Lamark

Lamarck's evolution theory of the early 1800's (before Darwin)
proposed that species evolved by necessity. According to Lamarck's
theory, for example, a short-necked giraffe initiates evolution of a longer
neck out of perceived necessity.


Darwin’s Alternative to Special
Creation, Acquired
Characteristics, and Random
Assembly


Basics of Natural Selection
n Variation in traits between members of a
species
n Some traits are passed across generations
(heritability)
n Some heritable traits affect reproductive
success
n Those traits gradually become more frequent
in a population


Domestication and Inheritance
of Traits


Humans selectively breed
plants and animals for certain
traits.

Nature automatically engages
in a selective breeding
program


Basics of Natural Selection
n Variation in traits between members of a
species
n Some traits are passed across generations
(heritability)
n Some heritable traits affect survival and
reproductive success
n Those traits gradually become more frequent
in a population


• Antibiotic Resistant
Bacteria

• Inﬂuenza

• Alcoholic Fruit Flies

• Lactose Tolerant
Adult Humans


Basic Implications
• Ecosystem: Organisms are all part of a highly
interconnected web of life.
– When one variable changes, new survival
challenges spread through the system and drive
selection.


Basic Implications
selection.

• Subtle factors drive big effects because
biological changes are cumulative.
– Compound interest


Basic Implications
selection.

• Subtle factors drive big effects because
biological changes are cumulative.
– Compound interest
• Complexity emerges from the application of
simple laws


Summary
• Darwin Provided an Alternative to Uniformitarianism
and Random Assembly Accounts of Species.

• Natural Selection
• Same Underlying Inheritance and Variation
Mechanisms that Enable Domestic Selection
• Struggle for life
• Variation of characteristics
• Differences in reproductive success
• Inheritance
• Gradual, Cumulative Change

Closing Comments
Natural Selection is Silent on Issues Related to
Theology, Metaphysics, Ethics, Morality, and the
Meaning of Life.

Scientiﬁc theories:

Motivate research programs - answer one question
and create two.

Connect disparate facts

Predict observations


Evolution part 1

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