Transcript evidence for evolution notes

What Scientists Agree On
– Earth is about 4.6 billion years old
– Life has inhabited Earth for most of its history
– All organisms living today have evolved from
earlier, simpler organisms
Evidence #1
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Fossils
• Preserved remains or imprints of an
organism
– Remains include bone, teeth, or shells
Fossils
Fossilized species in older rock are simpler
from those found in newer rock
140 million years
800 million years
Intermediate Fossils
• “Transitional fossils” link the
older and newer species
• Many have been found:
– Fish and Amphibians
– Dinosaurs and Birds
– Reptiles and Mammals
Intermediate Fossils
• In 1990, transitional whale
fossils were discovered
• Evidence shows that
whales evolved from 4legged land mammals
Whale Example
Why We Don’t Have More Fossil
Clues
• Fossils only form when the conditions are
right!
• Most common in streams, lakes, shallow
seas, and near volcanoes
Why We Don’t Have More Fossil
Clues
• Even if the conditions are right sometime
the body plan is not!
– Exoskeleton vs. soft body
VS.
Evidence #2:
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Anatomy Development
• Comparing different body structures
between species suggests relatedness
a. Homologous Structures
• Different functions but same
bones/structures
• These organisms likely evolved from a
closely related common ancestor
b. Analogous Structures
• Same functions but different
bones/structures
• These organisms likely evolved from
distantly related ancestors
c. Vestigial Structures
• Structures that are present but are no
longer needed for survival
Tailbone
Tonsils
Appendix
Evidence #3
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Biological Molecules Contain
Evolutionary Record
• If species change over
time, so does the genetic
material
• Study proteins and DNA
code for clues
Proteins
• Your DNA code determines what proteins
are being made in your cells
• Your proteins determine what you look
like!
• Proteins are made up of chains of amino
acids
• Closely related = similar amino acids =
similar proteins
Cytochrome C Protein
Relationship to Humans
Species
Protein
Differences
Gorilla
1
Rhesus Monkey
8
Mouse
27
Chicken
45
Frog
67
Lamprey
125
Evidence #4:
• Closely related species have more
similar embryo development
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Embryo Development
• Closely related species have more
similar embryo development