Download Evolution Evidence Overview

Evolution Evidence
Overview
By:
Historical Sciences –
Reconstructing a Crime
• Discuss: When someone is accused of committing a
crime, how are they shown to be guilty or not guilty?
– Eye witnesses, DNA evidence, finger prints, etc.
• One thing we can not do is rewind time to repeat the
crime.
• We can, however, use evidence to draw the most
reasonable conclusion.
• We will use this same process used in a court room to
determine if evolution is historically accurate.
Questions to Get You Thinking
• If evolution is true, what kind of evidence
might you suspect you would find in nature?
• If evolution is false, what kind of evidence
might you suspect you would find in nature?
• Is there any evidence to support the theory of
evolution?
• If so, what kind of evidence?
Evidence Overview
• Similarities between species showing
common ancestry
• Progressions of species changing over time
• Remnants of past generations within species
Similarities – Family Resemblance
• Discuss: Do people ever say that you look like
anyone else in your family? Why?
• In the same way that people in the same family
look alike, so species that are related also share
similarities inherited from common ancestors.
Examining the Evidence –
Similarities
• What might disprove evolution:
– species are totally unique, unlike each other.
• Strong evidence in support of evolution:
– Similarities from multiple disciplines agree –
genetics, anatomy, behavior, geography, etc.
– Species share greater number, intensity, and
variety of similarities the more recent they shared
a common ancestor
– The similarities shared between species are
arbitrary or harmful to have
Examples of Similarities
Between Species
• Vertebrates usually have a humerus, an ulna, a
radius, wrist bones, and five fingers, even though
they use them for very different purposes – walking,
grasping, flying, swimming, digging, etc.
Examples of Similarities Between
Species
• Almost all mammals have 7 neck vertebrae,
even though they use them very differently
Examples of Similarities Between
Species
• Orchids of incredible variety have the same
pattern of parts
Examples of Similarities Between
Species
• Though both groups are extremely diverse,
insects have 6 legs, while arachnids have 8.
Arachnids
Insects
Examples of Similarities Between
Species
• Echinoderms, though very diverse, have 5
sides.
Examples of Similarities Between
Species
• Species also share a number of molecular
similarities.
– Species share
• the same genetic language
• the same types of amino acids – L isomer
• The same kind of sugars – D isomer
Genetic Language
Amino acids
Sugars
Examples of Similarities Between
Species
• Humans share
98% of our genes
with chimpanzees
•
This picture graphically
represents a
comparison of one
gene, FOXP2, shared
by both humans and
chimps. The white
gaps are deletions or
insertions that differ
between humans and
chimps. The red spots
are significant genetic
differences between
humans and chimps.
The letters that form
the body of the chimp
are the shared
sequences.
Progressions of Change –
Putting the Frames of a Movie Together
• When we watch TV or a movie our brain puts
together individual frames into smooth movements.
• Evolutionary progressions also come in similar
"frame by frame" sequences.
Examining the Evidence –
Progressions
• What might disprove evolution:
– Species are shown to be unchangeable
– Species remains do not show progressions of change
• Strong evidence in support of evolution
– Modern dating techniques confirm the ages of fossils
within a progression
– Multiple traits are held in common by evolving species
showing they are related
– Multiple traits change over time within an evolving
species
Examples of Progressions - Whales
• Modern day whales
evolved from land
dwelling relatives of
hippos
•
Examples of
Progressions Whales
The back legs of the whales
become reduced over time
• The nose of the whales
moves to the top of the
head
• As some whales
transitioned from eating
with teeth to eating with
baleen, some intermediate
fossil species had both
teeth and baleen
– bottom right photo is of a
toothed whale with baleen
blood vessels
Examples of Progressions - Horses
• Horses have evolved to become larger, have
fewer toes, and to eat grass.
Remnants – Signs of Origins
• Coins minted in the U.S. have letters
on them that tell which mint they
came from.
• Discussion: Has anyone ever said that
you have an accent? Do you think you
do? What can we tell about where
someone is from based on how they
speak?
• Similar to the above signs of origins,
we can look at species and tell a lot
about their evolutionary history.
Remnants – Whale Legs
• Whales and dolphins
have the vestigial legs
early in development
• All whales and
dolphins have the
remains of hips and
legs inside their body.
Remnants – Fibulas
• Horses have vestigial bones in
their legs called fibulas.
– These bones easily break
causing the horse great
discomfort. Race horses have
their legs wrapped to help
prevent breaks.
• Many other species also have
vestigial fibulas, chickens are
one example.
• Discussion: Have you seen
this bone while eating
chicken?
Remnants in You!
•
•
•
•
•
Coccyx
Wisdom teeth
Ear muscles
Goosebumps
Nictitating eye
membrane
• Canine teeth
Genetic
Remnants
• Pseudogenes are genes that no longer
have their original function but are similar
to functional genes.
– Examples:
• humans can’t synthesize Vitamin C, but we
possess the pseudogene to.
• 51% of human scent genes have mutated into
pseudogenes
• Atavistic genes are genes are that are
typically pseudogenes but occasionally
mutate to be turned on again.
– Examples
• Toothless chickens and baleen whales can
grow teeth
• Whales grow hind legs
• Humans can grow tails
Review
1. Species share similarities that are signs of
their common ancestry.
2. There are progressions of species changing
over time.
3. Species have traits that are the remnants of
past generations.