Theories and Evolution
Catalyst: How does macroevolution/speciation occur?
When you hear the word theory, what do you think?
What are the two criteria of a good scientific hypothesis?
Theories and Evolution
By the end of today, all SWBAT…
Explain what makes a good scientific theory
What is a scientific theory?
Key Point #1: A scientific theory is a testable explanation of observations
Explains why things happenTestable and based on evidenceNot just a belief!
How is a THEORY different from a HYPOTHESIS?
HYPOTHESISTentative explanationbased on
observationsONE SCIENTISTExperiments must
stillbe conducted to
testhypothesis
I THINK I have an
idea!
How is a THEORY different from a HYPOTHESIS?
THEORYExplanation supported by many, many experiments
MORE THANONE 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 adaptFalse! Random mutations are required!
Believed acquired characteristics are inheritedFalse! My children won’t be born with tattoos!
Thanks, Darwin!
Charles Darwin rejected Lamarck’s theory of evolution, and created 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 had more children. This caused the mutation to become more common. Eventually, all giraffes have long necks.
Wolves
Wolves need to run to catch food. Since they run so often, they get faster. Children are born fast because the parents are fast. Why is this wrong? (Lamarck)
Children 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 wolves. The fast ones had more children. This caused the mutation to become more common. Eventually, all wolves will be fast.
Elephants
Larger elephants are more difficult to kill. Elephants got big from eating a lot. Children were born large because their parents ate a lot. Why is this wrong? (Lamarck)
Children 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 #3: 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. J’s roommate, Mr. Akingbola, keeps trying to convince Mr. J to teach intelligent design in biology class.
Write 5-7 sentences 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 Can be disproved or modified by new
evidence Key Point #2: Lamarck’s theory was
tested and proven wrong Key Point #3: Intelligent design
cannot be tested, so it is not a scientific theory
Exit Questions
Why was Lamarck’s theory of evolution rejected? Be specific: what is wrong with it?
Why is Intelligent Design not a scientific theory?Write in complete sentences!
Don’t talk during the Exit Question!