Principles of Evolution
Chapter 13
Science is
A mechanic can
only correct a mechanical flaw. He has no way of seeing a demon, let alone
fixing or getting rid of one.
To the owner, the
demon may be causing the intake flow problem, but that is of no concern to the
mechanic.
He does not know
if demons exist because they are not measurable. He can only deal with
material, measurable things --- the engine.
This is a natural
cause which explains the naturally occurring event."
Science is
Modern
science is a process by which we try to understand how the
natural world works and how it came to be that way.
The
realm of science is limited strictly to solving problems about the natural
world. Science is not properly equipped to handle the supernatural realm
(as such), nor the realm of values and ethics.
How Did Evolutionary Thought Evolve?
Early Biological
Thought Did Not Include the Concept of Evolution
Plato & Aristotle:
Unchanging perfect forms
Scala Naturale
Idea unmodified for 2000 years
Aristotles ladder of nature
And then
Exploration of
New Lands Revealed a Staggering Diversity of Life
Fossils were
Discovered
These
observations begged for an explanation!
Darwins not the only one
Even before
Darwin, a few people speculated that life had evolved
Georges Leclerc,
Comte de Buffon (1707-1788)
Species conceived by nature and produced by time
Darwins not the only one
"The
external world is all-powerful in alteration of the form of organized bodies..
. these [modifications] are inherited, and they influence all the rest of the
organization of the animal, because if these modifications lead to injurious
effects, the animals which exhibit them perish and are replaced by others of a
somewhat different form, a form changed so as to be adapted to the new
environment.
Geoffroy Saint-Hilaire, "Influence du
monde ambiant pour modifier les formes animales." 1833.
How Did Evolutionary Thought Evolve?
Some
Scientists Devised Nonevolutionary Explanations for Fossils
Cuvier: catastrophism
Change through time by removal of organisms
in catastrophes
Georges Cuvier (1769-1832)
Some Pre-Darwin Biologists Proposed
Mechanisms for Evolution
Inheritance
of acquired traits?
Darwins Voyage of Discovery
The Voyage of the Beagle
Darwin
spent most of this time exploring on land; three years and three months on
land, 18 months at sea.
His
work made his reputation as a geologist and collector of fossils, and his
detailed observations of plants and animals provided the basis for ideas which
he later developed into his theory of evolution by natural selection.
How Does Natural Selection Work?
Modern
Genetics Confirmed Darwins Assumption of Inheritance (Descent)
Natural
Selection Modifies Populations over Time
How Does Natural Selection Work?
A flowchart of evolutionary reasoning
How Do We Know That Evolution Has Occurred?
Fossils Provide Evidence of
Evolutionary Change over Time
Fossil
Discoveries Showed That Life Has Changed over Time
Progression from simple to more complex
Types of
fossils
Radiometric Dating
How Do We Know That Evolution Has
Occurred?
Comparative
Anatomy Gives Evidence of Descent with Modification
How Do We Know That Evolution Has
Occurred?
Functionless Vestigial Structures Are Inherited from Ancestors
How Do We Know That Evolution Has Occurred?
BUT: Some Anatomical Similarities Result from Evolution in Similar
Environments
Analogous
structures
Convergent Evolution
Comparative Embryology
Lemur, Pig and
Human Embryos
Embryological
Similarity Suggests Common Ancestry
How Do We Know That Evolution Has
Occurred?
Modern
Biochemical and Genetic Analyses Reveal Relatedness among Diverse Organisms
All
use DNA to store information
All
use RNA & ribosomes to turn genetic code into proteins
All
use same 20 amino acids
All
use ATP for ready energy
Sequence Conservation
What Is the Evidence That Populations Evolve by Natural Selection?
Controlled
Breeding Modifies Organisms
Dog diversity illustrates artificial
selection
Artificial Selection
What Is the Evidence That Populations Evolve by Natural Selection?
Evolution by Natural Selection Occurs Today
Brighter Coloration Can Evolve When Fewer Predators
Are Present
Natural Selection Can Lead to Pesticide Resistance
Experiments Can Demonstrate Natural Selection
Variations are
produced by chance mutations
Organisms become
adapted to a particular environment
A Postscript About the Nature of Science
Not a faith we
dont ask for belief
Look for
patterns, then test which ideas fit best to the data
NOT: have an
idea, look for patterns that are consistent with that idea
Evidence for
evolution is overwhelming not in doubt
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