Transcript Theories and Evolution

Theories and Evolution

Objective:
 SWBAT
explain what makes a good scientific
theory

Catalyst:
 When
you hear the word theory, what do you think?
 Byron wants to test whether coming to after school
tutoring every single day will increase his test scores.
 What
is the independent variable?
 What is the dependent variable?
Agenda
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

Catalyst
What is a scientific theory??
Intelligent design
What is a scientific theory?
Key Point #1: A scientific theory is
not just a hunch!
Explanation
of observations
Has been supported by many, many
experiments
Can be disproved or modified
How is a THEORY different from a
HYPOTHESIS?
I THINK I
have an
idea!
HYPOTHESIS
Tentative explanation
based on observations
ONE SCIENTIST
Experiments must still
be conducted to test
hypothesis
How is a THEORY different from a
HYPOTHESIS?
THEORY
Explanation supported
by many, many
experiments
MORE THAN
ONE SCIENTIST
Takes time!
Where did evolution start?

Key Point #2:
Evolution
is a theory… it has been revised
many times because of new evidence.
One
of the first evolution theorists was
Jean-Baptiste Lamarck who had some
pretty crazy ideas.
This reading is far beyond high school
level…
Instead of me re-writing it,
let’s see if we can work this
out together…

Why do you think Lamarck’s theory…

Didn’t stick?

Key Point #3:
Evidence
from experiments is used to
support, modify, and/or reject theories.

Scientists have rejected Lamarck’s theory because evidence has
shown that organism do not spontaneously change because of
their environment.
What did Darwin actually say?
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Key Point #4
Charles Darwin put forth the scientific theory of
evolution by means of natural selection in 1859.
The Key Statements
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1.
2.
3.
Darwin’s theory can be broken down into three
main statements:
There is some variation that can be passed down
from generation to generation.
There is competition (fighting) for limited resources
(like food or water).
Environmental pressures force natural selection to
select those individual with the heritable traits
best suited to survive to pass on their traits.
Look at this scenario
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3.
1.
2.
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There is one kind of finch back on the big main
island. This finch flies over to two different islands.
One island is hot with tons of insects to eat and the
other is shady with big trees that have large seeds.
Environmental
pressures
forcecan
natural
selection
to
There is competition
some variation
(fighting)
that
forbe
limited
passed
resources
down
select
thoseorindividual
with the heritable traits
from food
(like
generation
water).
to generation.
best
suited
to survive
toand
pass
on
their
traits.
We know
There
are that
lots
of
some
birds
birds
will
there’s
have
not
big
enough
beaks and
In
thisto
case,
the small
type
of
food Some
isSo
thesurvival
pressure.
Big
some
food
will
support
have
ALL of
beaks.
them.
will have
of the
seeds
bigand
beaks
need
long
slenderneed
fittest:
the
beaks
ones
with
some
theand
adaptations
willinsect-eaters
have fatbest
beaks.
suited
slender
beaksontothe
getisland
them will
out survive
of hiding.
for the food
and
reproduce, passing on their genes.
So, the finches…
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Ok, so we know that
natural selection causes
changes in the gene
pool.
Depending on the
specific environment of
the finches, they had
different traits
(specifically beak size
and shape).
But why were they
different species?
Lastly, Intelligent Design…
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Intelligent design is the “theory” that life
on this earth was created by an
intelligent designer
How come this is not taught in science
classes?
Testable!
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Intelligent design is not testable!
There is no way to prove, modify, or disprove this
theory that there was this intelligent creator!
The DEBATE!
Exit Question
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Why was Lamarck’s theory
discredited?
Why is Intelligent Design not
taught as a theory?