1. Evolution – Just A Theory?

2. Evolution in the News 1925: Scopes “Monkey” Trial
science teacher charged with contravening Tennessee’s Butler Act, which forbade the teaching of "any theory that denies the story of the Divine Creation of man as taught in the Bible, and to teach instead that man has descended from a lower order of animals."
1980s: Alabama and Louisiana laws mandating teaching of “creation science” found to be unconstitutional
Right now: Challenges to teaching of evolutionary theory versus “Intelligent Design” in Kansas, Michigan, Pennsylvania (aclupa.blogspot.com)

3. Charles Darwin Born 1809, 5th son of wealthy physician
Studied medicine and natural history in Edinburgh
Studied to be a clergyman at Cambridge

4. Charles Darwin’s Controversial Theory
Charles Darwin – 19th century scientist
Famous for Theory of Natural Selection
In a population, naturally occurring variations affect which individuals survive and reproduce
Natural selection - the force which acts on populations, and the best adapted organisms survive
Evolution - the process by which populations change over time
Darwin rarely used the word “evolution” so as not to imply progress in a certain direction or towards a set goal

5. Charles Darwin’s Controversial Theory
150 years of controversy!

6. Competing Belief
Many people, even today, do not believe in the theory of evolution, but instead, the idea of creationism.
Creationism is static and unchanging… but has meaning and purpose.

7. What is a Scientific Theory?
National Academy of Science:
“a well-substantiated explanation of some aspect of the natural world that can incorporate facts, laws, inferences, and tested hypotheses.”
Modern science is based on the scientific method

8. Darwin’s theory
Darwin published his findings from his trip around the southern hemisphere in a book called On the Origin of Species
Darwin visited the Galapagos Islands, a group of very small islands off the coast of Ecuador.
Even though the islands are close together, each island has a unique climate.
Darwin proposed that evolution worked by way of natural selection.

9. Charles Darwin – Voyage of the Beagle
1831: Joined the HMS Beagle on five year voyage to South America
Studied geology, paleontology, plants and animals

10. Animals of the Galapagos
Darwin could tell by the shape of the Giant
Tortoises’ shells and their neck length
which island they were from.

11. Darwin’s theory
Organisms differ, and some of this variation is heritable.
Some cows produce more milk, some apple trees produce larger apples, etc.
People now use artificial selection: nature provides the variation, but humans select for the variations they find useful
Ex. Only breed the dogs that lose the least amount of fur.

12. Darwin’s theory
2. Organisms produce more offspring than can survive, and many that do survive do not reproduce.
3. Because more organisms are produced than can survive, they compete for limited resources.
Struggle for existence.
In this struggle, predators that are faster get more prey.

13. Darwin’s theory
4. Natural selection causes species to change over time.
Survival of the fittest!!! (natural selection)
Adaptation is any inherited characteristic that increases an organism’s chance for survivial.
Those individuals best adapted to their environment will survive and reproduce.

14. Darwin’s theory
5. Species alive today are descended with modification from ancestral species that lived in the distant past.
All living organisms are
Related to one another-
common descent.
Single “tree of life” links
all living things (classification)

15. Darwin’s Finches Finches looked different on different islands
Different beak shapes depending on feeding habits
Finches on different islands can still interbreed but geographically isolated
in the process of becoming different species

16. Evolution by Natural Selection
Natural selection - force of nature that acts on populations
Individuals that compete more effectively pass on their traits to the next generation
Natural variation plus natural selection = evolution
All species could share common ancestor

17. Evidence of Evolution Molecular Evidence 2. Fossils
Study proteins (amino acid sequences)
Biologists believe that the greater the similarity between the amino acid sequences of two organisms, the closer their relationship
2. Fossils
Fossil evidence can show us what older, possibly extinct organisms looked like and we can compare them to organisms known today.
3. Homologous Structures
Similar bone structure can reveal evidence of evolutionary relationships.
4. Comparative Embryology
The more similar organisms are in their embryological development, the more closely they are related.

18. Molecular Evidence The more amino acids that are
the same, the closer the
evolutionary relationship
between the organisms.
Hemoglobin, protein in blood,
is often looked at for
comparisons – all of these
organisms have blood.

19. Fossils Radioactive dating gives relatively exact dates for fossils.
If undisturbed, the older fossils
will be found deeper in the ground
than younger fossils.

20. Homologous Structures
Structures have different
mature forms , but from the
same type of tissue.
Suggests common
ancestor.
Analogous structures:
Similar in function, but
not from the same ancestor.

21. Embryology Embryological development The developing embryos of many
very different organisms are
surprisingly similar in their early
stages.

22. Ideas that Shaped Darwin’s Theory
At the time Darwin was doing his research, the majority of people in the world though that the earth was only a few thousand years old.
5 main scientists helped shape our modern theory of evolution.

23. Classification of Species
Carl Linnaeus (1700s)
Identify relationships between groups of organisms
Species: groups of organisms based on physical resemblances and ability to interbreed
Created system of classification - taxonomy
Canidae
Canis
Vulpes
familiaris
lupus
vulpes
fulva
Dog
Wolf
European fox
American fox
Family
Genus
Species
Common name

24. How old is the earth?
James Hutton and Charles Lyell, both geologists, helped
scientists realize that the earth is many millions of years
old.
Contrary to popular religious beliefs at the time.
James Hutton
Charles Lyell

25. Lamarck – Theory of Evolution
Jean-Baptiste Lamarck – French naturalist
By the use or disuse of organs, organisms acquired or lost certain traits during their lifetime.
Organisms pass on acquired characteristics to next generation
Organisms adapt to different environments, causing branching of species
“Use it or lose it”

26. Lamarck – Theory of Evolution

27. But how are species selected in nature?
Insight from Thomas Malthus: struggle for existence
Constant pressure of expanding population for resources
If the population keeps growing unchecked, humans would run out of living space and food (1798).
He felt the only thing that could limit population growth would be war, famine and disease.
Was he correct?

28. Darwin’s Career
1858: Alfred Wallace published a similar theory to Darwin’s
1859: Darwin published The Origin of Species by Means of Natural Selection, or The Preservation of Favoured Races in the Struggle for Life
Darwin dubbed “most dangerous man in England” but became famous and well-respected scientist
Later published The Descent of Man and Selection in Relation to Sex and The Expression of the Emotions in Man and Animals

29. Major Misconception about Evolution
Evolution has never been observed.
Peppered moths during industrial revolution.
Change has been directly observed.
Antibiotic Resistance
Flu Vaccines
Creation of new species of bacteria has been directly observed.