Transcript The EVIDENCE for Evolution

The EVIDENCE for Evolution
In
order for an idea to be
considered a “scientific”
idea, it must be TESTABLE
with experiments,
observations, data and
conclusions.
EXTRAPOLATE

TO INFER (AN UNKNOWN- such as how
evolution has taken place ) FROM
SOMETHING THAT IS KNOWN.
The FOSSIL RECORD
2.Fossil: any remains of a living
thing preserved by sedimentation
petrification or mineral
replacement
Fossilization is RARE!!! Because
most organisms are decayed by
oxygen , water, fungus, bacteria
etc. Leaving no trace of their
existence
Examples of FOSSILS
 Bones
 Insect
in amber
 Scat (poop!)
 Footprints
 Pottery shards,
stone tools
 Imprints
(leaves,
skin, bacteria)
 Eggs
 Burrows
 Nests
 Original remains
Corprolite- fossilized dinosaur
feces
Baby Wooly Mammothpreserved in permafrosst
Man preserved in ice- believed
to be over a 5,000 yrs old
Tollund man- found in a peat
bog – believed to be 1,500
yrs. old
Trilobite and hand print
organisms preserved in
amber
Insects in amber
Petrified wood
Mineralization of bone
Stromatolites- oldest known
fossils- structures created by
blue-green algae
Dinosaurs
Wolf-like mammal that became
extinct ~1 million years ago (found
in South Dakota)
Cave bear skullsover 9 feet tall when
on hind legs, became
extinct ~ 20,000 years
ago
Ginkgo leaf54 million
years old
Fish eating a fish
fossil!
LUCY- found in 1974Ethiopia, Africa- thought to be
3.2 million yrs old
Transitional fossil – Idaancestor of humans
What do Fossils tell us???
When fossils are found, they can be
compared to modern day species to find
similarities, differences, relationships,
geographical locations and age.
 Strata- which are layers of earth in
which fossils are found can help us
 determine how long ago the organism
lived on earth.
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Radioactive Dating
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Technique used to date materials based upon
the known decay rates of naturally occurring
radioisotopes and current abundances
Invented in 1947 by William Libby; he
received the Nobel Prize in chemistry in 1960
Half-life: the amount of time necessary for
½ of the radioisotopes in a sample to decay
into the more stable form
Radioisotope
Half-Life
Polonium-215
.0018 seconds
Bismuth-212
60.5 seconds
Sodium-24
15 hours
Iodine-131
8.07 days
Cobalt-60
5.26 years
Radium-226
1600 years
Carbon-14
5730 years
Uranium-238
4.5 billion years
HOW IT WORKS- RADIO
CARBON DATING
Transitional Forms
Fossil remains that link OLD species to
NEW species
 Fossils have been found that link
modern day whales to animals that
lived on LAND

Evolution of
the foot of
horses and their
ancestors
Beluga Whale nostril
position:
Homologous Structures
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Structures that
share a common
ancestry:
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Bird wing, dolphin
fin, human arm
Similar structures
means similar
DNA, and similar
DNA means they
shared a common
ancestor
Vestigial Structures
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Vestigial structures are
structures that
organisms possess that
have NO APPARENT
FUNCTION
Examples: human
appendix, whale pelvis,
snake leg buds, human
tail bone, human ear
muscles
Leg buds of a python snake
EXAMPLES : WHALE PELVIS
So What do Vestigial
Structures Tell Us????
If an organism has the DNA to cause
the development of a specific structure,
then the organism’s ancestors must
have had a use for that structure in the
past.
 Herbivores have huge appendicesmaybe humans used to be strictly
herbivores???
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