1. Biology 1130
March 19th
Please do not eat or drink in our classroom.
Attendance Poll

2. Announcements
• Chapter 9 reading quiz deadline: March 26th
• Chapter 10 reading quiz deadline: March 28th

3. Let’s Review!
• What’s a hypothesis? What notable features
does a hypothesis have?
• What’s the scientific method?

4. Darwin’s Theory of Natural Selection
and its precursors

5. What’s a Scientific Theory?
• The result of repeated hypothesis testing
• Provides an explanatory model in a scientific
discipline
• The best explanation for what we see in the
natural world
• As close to a fact as we can get

6. What did Western Europeans
believe before the 1550s?
• The Earth was flat
• The Sun and other
heavenly bodies moved
around the Earth
• The Earth is young
• The accounts of organismal
and human creation in
Genesis were true:
– Fixity of Species
– Great Chain of Being

7. European History
(1400s – 1900s)
• What were some of the major discoveries,
wars, and social events of this time period?
• How did these events change how people saw
the world?
• How might these events have influenced
scientific thought?

8. Scientific Breakthroughs
in the Renaissance and later
• Heliocentric, rather than geocentric universe
• Earth is round
• Invention of telescopes & microscopes

9. If the Biblical account of
special creation is literally true, then…
• There should be no evidence that organisms have
changed over time
• All features of organisms should be perfectly designed
for their function
• There should be no features that have no obvious
function
• There should be no similarities between organisms
• There should be no extinct organisms (that didn’t die in
the flood)
• There should be no evidence of organisms existing more
than 6000 years ago

10. Discoveries that challenged the Biblical
account of creation (1700 and 1800s)
 Why organisms were more diverse than in the
Bible

11. “New” Continents, “New” Species

12. Invention of the microscope

13. Breakthroughs in Biology in the
Renaissance and later
• Why organisms were more diverse than in the
Bible
 Apparently extinct organisms

14. Mary Anning, Fossil Discoverer

15. Breakthroughs in Biology in the
Renaissance and later
• Why organisms were more diverse than in the
Bible
• Apparently extinct organisms
 Gross anatomical similarities between organisms

16. Homology of mammal forelimbs
Humerus
Radius
and ulna
Carpals
Metacarpals
Phalanges
Bat Sea lion Lion Chimpanzee Human

17. Order Primates
Family Hominidae
Subfamily Homininae
Squirrel Common
monkey Orangutan Gorilla chimpanzee Bonobo Human
increase in size of
genital structures
delayed sexual maturity
broad incisors
shortened canine teeth
enlarged brow ridges
elongated skull
reduced hairiness
large brain
no tail
more erect posture
increased flexibility of thumb
Mammal ancestor

18. Breakthroughs in Biology in the
Renaissance and later
• Why organisms were more diverse than in the
Bible
• Apparently extinct organisms
• Gross anatomical similarities between organisms
 Vestigial structures

19. “Useful” trait in primate relative Vestigial trait in human
(a) Tail bone
(b) Goose bumps

20. Breakthroughs in Biology in the
Renaissance and later
• Why organisms were more diverse than in the
Bible
• Apparently extinct organisms
• Gross anatomical similarities between organisms
• Vestigial structures
 Similar embryonic development between species

21. Comparative Embryonic Development
Snake Chicken Possum Cat Bat Human
Pharyngeal
Early slits
embryo
Tail
Intermediate
embryo
Late
embryo

22. Breakthroughs in Biology in the
Renaissance and later
• Why organisms were more diverse than in the
Bible
• Apparently extinct organisms
• Gross anatomical similarities between organisms
• Vestigial structures
• Similar embryonic development between species
 Evidence that organisms have changed over time

23. Horses and their ancestors
Equus
Merychippus
1 toe
Mesohippus 3 toes
Hyracotherium
(Eohippus)
3 toes
4 toes
Horse ancestor Modern horse
55 40 17 4
Millions of years ago

24. Darwin and the armadillos

25. How can we explain all of this??
• Why organisms were more diverse than in the
Bible
• Apparently extinct organisms
• Gross anatomical similarities between organisms
• Vestigial structures
• Similar embryonic development between species
• Evidence that organisms have changed over time

26. Darwin’s Voyage on the Beagle

27. Individuals who influenced Darwin
• Age of the Earth:
– Lyell
• Similarities between organisms:
– Ray
– Linnaeus
• Fit between organisms and their environments:
– Buffon
– Lamarck
• Economics (?!):
— Malthus

28. Charles Lyell: Uniformitarianism
• 1830s
• Uniformitarianism &
deep time

29. Uniformitarianism
• Geologic processes (wind and water erosion,
sedimentation, flooding, volcanic eruptions)
are constant now and have been in the past
• These processes take place over a long time
• The Earth is really old!

30. John Ray
• Late 1600s
• Definition of
species
(reproductive
isolation)

31. Carolus Linnaeus:
Linnaean Classification of Organisms
• 1735
• Taxonomy (study of
relationships between
organisms)
• included humans
• differences and
similarities between
species
• descent from a
common ancestor

32. Order Primates
Family Hominidae
Subfamily Homininae
Squirrel Common
monkey Orangutan Gorilla chimpanzee Bonobo Human
increase in size of
genital structures
delayed sexual maturity
broad incisors
shortened canine teeth
enlarged brow ridges
elongated skull
reduced hairiness
large brain
no tail
more erect posture
increased flexibility of thumb
Mammal ancestor

33. Georges Leclerc Comte de Buffon
• 1749
• organisms are “well-
suited” to their
environments
• adaptation
• but against
“transmutation”

34. Jean-Baptiste, Chevalier de Lamarck
• Late 1700s
• Inheritance of
acquired
characteristics
• first person to try to
explain adaptation

35. Lamarck’s Inheritance of Acquired
Characteristics

36. Thomas Malthus
• 1798
• Economist
• Populations have
finite resources
• More individuals
born in most species
than can survive

37. Malthus’ observation about
populations and their resources

38. Charles Darwin
• Voyage of the Beagle
(1830s)
• On the Origin of
Species published
(1859)
• Notice the gap in
time…

39. Charles Darwin:
Voyage of the Beagle (1830s)

40. What Darwin saw…
• Similarities in Galapagos & South
American finches
• Descent from a common ancestor
• Differences seemed to be related to
food

41. What Darwin knew…
• Knew about Malthus’
idea
• Knew about artificial
selection
• Sexual reproduction
produced variation

42. Alfred Russel Wallace:
Almost “scooped” Darwin
• 1848: Amazonian
journey
• knew species well-suited
to environments
• Wrote to Darwin (1858)
• 1859 Darwin published
On the Origin of Species
• Why did Darwin wait?

43. For Natural Selection to Happen, There Must Be:
1. Variation
2. Variation must be heritable
3. Some variants better able to survive OR
reproduce than others in a given
environment (reproductive fitness =
differential reproductive success)
 Over time, accumulation of successful
variants result in adaptation

44. More about natural selection
• Survival only matters until the point of
reproduction
• Environments contain selective
pressures (predators, competition for
food / mates)
• Environmental context is key (example:
wooly mammoths)

45. More about natural selection
Geographical isolation can produce new species:
– if groups are exposed to different selective pressures
in their respective environments
– gradually differences will accumulate
– groups will no longer be able to interbreed
• Individuals survive & reproduce, but populations
evolve

46. Evolution Example: “Peppered” Moths in England
What’s the
selective pressure
in the
environment?
How did the
population evolve?

47. Evolution Example:
antibiotic-resistant bacteria (example: MRSA)
• What’s the selective
pressure in the
environment?
• How did the
population evolve?

48. Misconceptions about Evolution
• It’s not testable
• How does one formulate a testable hypothesis
about something that happened in the past?
• It’s all about survival
• If something exists, it’s the result of natural
selection (adaptationism) (example: male
nipples)

49. Follow-up Questions
• What’s the Great Chain of Being?
• What’s the Fixity of Species?
• How do geocentric and heliocentric universes differ?
• What’s a vestigial trait?
• What’s uniformitarianism? What’s deep time?
• What’s a species? What’s taxonomy?
• What’s the inheritance of acquired characteristics?
• What is adaptation?
• What is required in order for natural selection to occur?

50. Judgment Day:
Intelligent Design on Trial