Download Theories and Evolution

Theories and Evolution
Write in complete sentences!
Don’t talk during the Catalyst!
Put your Post-Lab questions in your group folder.
Catalyst:
 How
does speciation (one species splitting into two)
occur?
 When you hear the word theory, what do you think?
Write at least three complete sentences.
 Flashback Friday: What are the two criteria of a good
scientific hypothesis?
Objective
 SWBAT
theory
explain what makes a good scientific
What is a scientific theory?

Key Point #1:
A
scientific theory is a testable
explanation of observations
Not just a hunch!
 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?

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 TOUGH…
Instead of me
re-writing it,
let’s see if we
can work this
out together…

What was wrong with Lamarck’s
theory?

Key Point #2: Lamarck’s theory was
tested and proven wrong.
Believed
organisms can force themselves
to adapt
False!
Random mutations are required!
Believed
acquired characteristics are
inherited
False!
My children won’t be born with tattoos!
Thank goodness!
Thanks, Darwin!

Key Point #3: Darwin developed the
modern theory of evolution in 1859.
 Random
mutation
 Environmental pressure
 Natural selection for heritable traits
 Evolution
Giraffe

Giraffes eat leaves on tall trees. Since they stretch their
necks so often, the neck grows. Children inherit the
stretched out necks.
 Why
is this wrong (Lamarck)?
 Can’t
make your neck grow by stretching it!
 Children wouldn’t inherit stretched out necks, anyways.
 What
really happened (Darwin)?
 Random
mutations produced some giraffes with longer necks than
others.
 The ones with long necks were able to have more children.
 This caused the mutation to become more common.
 Eventually, all giraffes have long necks.
Wolves

Cougars need to run to catch food. Since they run so
often, they get faster. Offspring are born fast
because the parents are fast.
 Why
is this wrong? (Lamarck)
 Offspring
aren’t born fast just because parents exercise!
 If I lift weights, are my kids born with big biceps? NO!
 What
really happened? (Darwin)
 Random
mutations produced some fast cougars.
 The fast ones were able to have more children.
 This caused the mutation to become more common.
 Eventually, all wolves have long necks.
Elephants

Larger elephants are more difficult to kill. Elephants
got big from eating a lot. Offspring were born
large because their parents ate a lot.
 Why
is this wrong? (Lamarck)
 Offspring
aren’t born big just because parents eat lots!
 If I eat a lot, are my kids going to come out 200 lbs? NO!
 What
really happened? (Darwin)
 Random
mutations produced some larger elephants.
 The large ones had more children.
 This caused the mutation to become more common.
 Eventually, all elephants were large.
Intelligent Design
Intelligent design = some organisms did not
evolve, they were created in their final form
by an intelligent designer
 Key Point #4:

 Intelligent
design cannot be tested, so it is not a
scientific theory


There is no way to prove, modify, or disprove
the theory
It is not science!
Guided Practice
Mr. Sanacore’s BFFAE, Ms. Ryan, keeps trying
to convince Ms. S to teach intelligent design in
biology class.
 Write one paragraph to answer…

 What
is intelligent design?
 Why is intelligent design not a scientific theory?
 Why is intelligent design not taught in biology
class?
Key Point Wrap-Up

Key Point #1: A scientific theory is a testable explanation
of observations


Key Point #2: Lamarck’s theory was tested and proven
wrong



Can be disproved or modified by new evidence
Believed organisms can force themselves to adapt and acquired
traits are inherited
Key Point #3: Darwin developed the modern theory of
evolution in 1859
 Random mutation, Environmental pressure, Natural selection,
Evolution
Key Point #4: Intelligent design cannot be tested, so it is
not a scientific theory
Exit Questions
Write in complete sentences!
Don’t talk during the Exit Question!
WHY was Lamarck’s theory of
evolution rejected? Be specific: what
is wrong with it?
 Why is Intelligent Design not a
scientific theory?
 Reflect on your Weekly Goal.
 Feedback?
