Transcript Evidence for Evolution

Evidence for Evolution
Bill Nye:
http://www.youtube.com/watch?v=sv
HQ4BQY__o&feature=results_video
&playnext=1&list=PL51E21E1D19F
B81E0
Major Evidence for Evolution
Fossil record
 Homologous structures
 Vestigial structures
 Biochemical evidence
 Embryological development

Charles Darwin

1859 – “Origin of Species”
published
1.
2.

Argued from evidence that species
inhabiting Earth today descended
from ancestral species
Proposed a mechanism for evolution
 Natural Selection
Many scientists helped pave the
way for Darwin’s Theory
Theory of Evolution By Natural Selection
In each generation of a species,
individuals have slight
differences.
 Sometimes these variations
make an individual more
successful in its environment

(more food, live longer,
reproduce more, attract better
mates). Then individual may
then reproduce and pass this
variation on to its offspring.
 Then the individual may
reproduce and pass this
variation on to its offspring.

Natural Selection
 Variations
in individuals are
controlled by genes.
 Individuals have no control
over what variations they
will have.
 Useful
variations are NOT
ALWAYS passed on.
 Variations
that are not useful
may also be passed on.
Alfred Russel Wallace

co-discovered natural selection and prompted
Darwin to finally rush his Origin of Species to
press.

One of the modern world’s greatest scientific
adventurer explorers

eight-year exploration of Southeast Asia and the
Malay Archipelago he wrote The Malay
Archipelago in 1869,

Geographical Distribution of Animals (1876)
is one of the seminal works in the field.

the workhorse of Darwinian evolution,
diverged from Darwin’s methodological
naturalism (i.e., the notion that scientists must
invoke only natural processes functioning via
unbroken natural laws in nonteleological
ways) to propose a theory of evolution
defined by intelligence and design.
Jean Lamarck
1. Fossil Record

What does the Fossil Record tell
us about organisms?



Looks (size, shape, etc.)
Where or how they lived
What other organisms they lived
with



What time period they
lived in (based on
location in rock layers)
What order living
things came in (based
on location in rock
layers)
Transitional forms
 Organisms that were
intermediate
(between) two other
major organisms
Example: Horse
 Homologous
Structuresbodily structures that are
similar in structure, but
different in function, due to
sharing a common ancestor
2. Homologous Structures
Homologous Structures
Analogous Structures

Analogous structures- bodily
structures that are similar in
function, but not in structure.
NOT EVIDENCE OF COMMON
ANCESTRY.
 Example: wings of a bee and
wings of a bird
3. Vestigial Structures

Structures that serve no function
but useful structures in earlier
ancestors
 Examples: Ear muscles
 Human tailbone
 Appendix
Vestigial Organs
4. Embryological Development

Embryo- fertilized egg that will/is in the
process of growing into a new individual

Closely related organisms go through
similar developmental stages early in
development

All vertebrates have gill pouches sometime
during their early development
5. Molecular/Biochemical Evidence
o
DNA used to translate
nucleotide sequences into
amino acid is essentially the
same in all organisms
o
Proteins in all organisms are
composed of the same set of
20 amino acids
Powerful argument in favor
of the common descent of
the most diverse organisms.
o
Universal Code
Biochemical Compound Ex

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
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DNA
Cyt C
20 amino acids
Some enzymes
Molecular/Biochemical Evidence

Cytochrome c
 An ancient protein common to all aerobic (oxygen
breathing) organisms
 Amino acid sequence to make cytochrome c differs
increasingly the more distantly related two
organisms are (very similar amino acid sequence =
closely related)
 The cytochrome c of humans and chimpanzees is
identical
DNA
Cyt C