Transcript Chapter 2 the Development of Evolutionary Theory

Chapter 2
The Development of Evolutionary
Theory
Evolution?
• Brian Malow
http://www.youtube.com/watch?v=Ohvh47v
Tp34&feature=related
Introduction to the Subject of
Evolution
• Evolution is the most fundamental of all
biological processes, but one of the most
misunderstood.
• Humans evolved from a species that lived
some 6-8 million years ago (mya), not
monkeys or chimpanzees.
 Evolution takes time;
hence, the appearance
of a new species is rarely
witnessed
(microevolutionary
changes occur, however:
see Chapt. 1)
 The subject of evolution
is controversial,
especially in the U.S.
because of conflicting
spiritual teachings
Evolution Is a Theory
• The theory has been tested and subjected to
verification through accumulated evidence
(and has not been disproved)
• The theory of evolution has been supported
by a mounting body of genetic evidence.
• The theory has stood the test of time.
• The theory continues to grow.
A Brief History of Evolutionary
Thought
• Evolutionary principles were developed in
western Europe, made possible by scientific
thinking dating to the 16th century.
• Western science, however, borrowed ideas
from Arab, Indian, and Chinese cultures where
notions of biological evolution had already
developed.
• It was the theory that was new.
Natural Selection
 Natural selection in the theory of evolution refers to
genetic change or changes in the frequencies of
certain traits in populations due to differential
reproductive success between individuals.
 The most critical mechanism of evolutionary change,
first explained by Charles Darwin
 Same conclusions were independently reached by
Alfred Russel Wallace.
 A predominant feature of European worldview was,
however, that all forms of nature never changed….
Fixity of Species
• The notion that species, once created, can
never change.
• An idea opposed to theories of biological
evolution.
• To challenge the idea was to challenge the
perfection of God’s design.
The Scientific Revolution
 Came with the
discovery of the New
World, introducing
new ideas and
challenging
fundamental views
about the planet.
 Exposure to new
plants and animals
increased awareness
of biological diversity.
 John Ray, a minister educated
at Cambridge University,
developed the concept of
species.
 He recognized that groups of
plants and animals could be
differentiated from other
groups by their ability to mate
with one another and produce
offspring.
 He placed such groups of
reproductively isolated
organisms into a single
category, which he called the
species.
 Carolus Linnaeus, a Swedish
naturalist who developed a
method of classifying plants and
animals.
 In Systema Naturae, first
published in 1735, he
standardized Ray’s use of genus
and species terminology and
established the system of
binomial nomenclature.
 He added two more categories:
class and order.
 Linnaeus’ four-level system
became the basis for taxonomy.
 Erasmus Darwin, Charles
Darwin’s grandfather
 Physician, poet, and leading
member of an intellectual
community in England
 In a poem, expressed the view
that life had originated in the
seas and all species descended
from a common ancestor.
 Charles read his grandfather’s
writings, but how much he
was influenced by them is
unknown.
 Jean-Baptiste Lamarck
developed a theory to explain
the evolutionary process,
known as the inheritance of
acquired characteristics.
 An example is the giraffe:
having stripped the leaves
from the lower branches of a
tree, the animal tries to reach
leaves on upper branches.
 The neck becomes slightly
longer.
 The longer neck is passed on
to offspring.
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