1. AIM:
How can we know that evolution has
actually occurred?
Warm – up:
How does Darwin explain the
presence of organisms alive
today?

2. LaMarck
• Organisms adapted to their environments
ØThrough acquired traits
ØChange in their lifetime
v Use & Disuse: organisms lost parts of their body
because they did not use them (like the missing
eyes and digestive system of the tapeworm)
v Perfection with Use & Need: the constant use of an
organ leads to an increase in size of that organ
ØTransmit acquired characteristics to next
generation

3. LaMarck
• Organisms adapted to their environments
ØThrough acquired traits
ØChange in their lifetime
v Use & Disuse: organisms lost parts of their body
because they did not use them (like the missing
eyes and digestive system of the tapeworm)
v Perfection with Use & Need: the constant use of an
organ leads to an increase in size of that organ
ØTransmit acquired characteristics to next
generation

5. But the fossil record shows…

6. Descent with Modification
Darwin’s idea that each species living
today arose from a pre-existing
species!

8. Hundreds of millions of years passed before atmospheric
oxygen levels were high enough to support eukaryotes.

10. Evidence Supporting Evolution

11. Evidence Supporting Evolution
• Fossils (descent with modification)

12. Evidence Supporting Evolution
• Fossils (descent with modification)
• Comparative biochemistry

13. Evidence Supporting Evolution
• Fossils (descent with modification)
• Comparative biochemistry
• Comparative cell biology

14. Evidence Supporting Evolution
• Fossils (descent with modification)
• Comparative biochemistry
• Comparative cell biology
• Comparative embryology

15. Evidence Supporting Evolution
• Fossils (descent with modification)
• Comparative biochemistry
• Comparative cell biology
• Comparative embryology
• Comparative anatomy

17. Fossils as Evidence

18. Fossils as Evidence
• A fossil is the remains of organisms that
lived in the past.

19. Fossils as Evidence
• A fossil is the remains of organisms that
lived in the past.
• They are preserved by natural processes
(in ice, rock, etc.)

20. Fossils as Evidence
• A fossil is the remains of organisms that
lived in the past.
• They are preserved by natural processes
(in ice, rock, etc.)
• Examples: bones, shells, footprints,
imprints

21. Fossils as Evidence
• A fossil is the remains of organisms that
lived in the past.
• They are preserved by natural processes
(in ice, rock, etc.)
• Examples: bones, shells, footprints,
imprints
• Generally, found in sedimentary rock that
has been quickly covered by silt. Why?

23. How old are fossils?

24. How old are fossils?
• Relative dating: Fossils can be dated in
correlation with the age of the strata (layer
of rock) they are in.

25. How old are fossils?
• Relative dating: Fossils can be dated in
correlation with the age of the strata (layer
of rock) they are in.
• Absolute Dating: Using radioactive
isotopes (half life) to get a more accurate
estimate of age.

28. Problems with Fossils?

29. Problems with Fossils?
• Dating is only an approximation

30. Problems with Fossils?
• Dating is only an approximation
• No fossils of early or soft-bodied
organisms

31. Problems with Fossils?
• Dating is only an approximation
• No fossils of early or soft-bodied
organisms
• Holes in the fossil record

32. Problems with Fossils?
• Dating is only an approximation
• No fossils of early or soft-bodied
organisms
• Holes in the fossil record

33. Problems with Fossils?
• Dating is only an approximation
• No fossils of early or soft-bodied
organisms
• Holes in the fossil record
So what do scientists turn to?

34. Land Mammal
?
?
?
?

35. Land Mammal
?
?
e the ?
re ar tes?
Whe edia ?
In term

36. Land Mammal
?
?
e the ?
re ar tes?
Whe edia ?
In term

37. Land Mammal
?
?
e the ?
re ar tes?
Whe edia ?
In term

38. Land Mammal

39. 2006 Fossil Discovery of Early
Tetrapod
• Missing link from sea to land animals

40. 2006 Fossil Discovery of Early
Tetrapod
• Missing link from sea to land animals

42. Comparative Biochemistry &
Cell Biology show that…

43. Comparative Biochemistry &
Cell Biology show that…
• the genetic code in nucleic acids is almost
universal

44. Comparative Biochemistry &
Cell Biology show that…
• the genetic code in nucleic acids is almost
universal
• physiological processes follow common
metabolic pathways

45. Comparative Biochemistry &
Cell Biology show that…
• the genetic code in nucleic acids is almost
universal
• physiological processes follow common
metabolic pathways
• ATP is the universal form of energy

46. Comparative Biochemistry &
Cell Biology show that…
• the genetic code in nucleic acids is almost
universal
• physiological processes follow common
metabolic pathways
• ATP is the universal form of energy
• Organisms that are related often have
similar types of proteins and antibodies

47. Comparative Biochemistry &
Cell Biology show that…
• the genetic code in nucleic acids is almost
universal
• physiological processes follow common
metabolic pathways
• ATP is the universal form of energy
• Organisms that are related often have
similar types of proteins and antibodies

48. Comparative Biochemistry &
Cell Biology show that…
• the genetic code in nucleic acids is almost
universal
• physiological processes follow common
metabolic pathways
• ATP is the universal form of energy
• Organisms that are related often have
similar types of proteins and antibodies

49. Comparative Biochemistry &
Cell Biology show that…
• the genetic code in nucleic acids is almost
universal
• physiological processes follow common
metabolic pathways
• ATP is the universal form of energy
• Organisms that are related often have
similar types of proteins and antibodies

50. Comparative Biochemistry &
Cell Biology show that…
• the genetic code in nucleic acids is almost
universal
• physiological processes follow common
metabolic pathways
• ATP is the universal form of energy
• Organisms that are related often have
similar types of proteins and antibodies

52. Comparative Embryology

53. Comparative Embryology
• Species that are known to be closely
related show similar embryonic
development.

54. Comparative Embryology
• Species that are known to be closely
related show similar embryonic
development.
• Inference: The longer two embryos stay
looking similar, the more closely related
they are.

57. Comparative Anatomy

58. Comparative Anatomy
• Study of biological structures in different organisms

59. Comparative Anatomy
• Study of biological structures in different organisms

60. Comparative Anatomy
• Study of biological structures in different organisms
• Homologous structures: structures in different species
that have a similar design and position but serve
different purposes in species that live in different
environments.

61. Comparative Anatomy
• Study of biological structures in different organisms
• Homologous structures: structures in different species
that have a similar design and position but serve
different purposes in species that live in different
environments.
ex. Pentadactyl limb in mammals

62. Comparative Anatomy
• Study of biological structures in different organisms
• Homologous structures: structures in different species
that have a similar design and position but serve
different purposes in species that live in different
environments.
ex. Pentadactyl limb in mammals
• Divergent evolution

63. Comparative Anatomy
• Study of biological structures in different organisms
• Homologous structures: structures in different species
that have a similar design and position but serve
different purposes in species that live in different
environments.
ex. Pentadactyl limb in mammals
• Divergent evolution

64. Comparative Anatomy
• Study of biological structures in different organisms
• Homologous structures: structures in different species
that have a similar design and position but serve
different purposes in species that live in different
environments.
ex. Pentadactyl limb in mammals
• Divergent evolution
• Analogous structures: Structure of two unrelated species
that can evolve to look alike on the basis that they serve
a similar function in a similar environment.

66. Analogous structures

67. Analogous structures

68. Analogous structures
• Separate evolution of structures

69. Analogous structures
• Separate evolution of structures
– similar functions

70. Analogous structures
• Separate evolution of structures
– similar functions
– similar external form

71. Analogous structures
• Separate evolution of structures
– similar functions
– similar external form
– different internal structure & development

72. Analogous structures
• Separate evolution of structures
– similar functions
– similar external form
– different internal structure & development
– different origin

73. Analogous structures
• Separate evolution of structures
– similar functions
– similar external form
– different internal structure & development
– different origin
– no evolutionary relationship

74. Analogous structures
• Separate evolution of structures
– similar functions
– similar external form
– different internal structure & development
– different origin
– no evolutionary relationship
Solving a similar problem with a similar solution

75. Analogous structures
• Separate evolution of structures
– similar functions
– similar external form
– different internal structure & development
– different origin
– no evolutionary relationship
Don’t be fooled
by their looks!
Solving a similar problem with a similar solution

76. Vestigial Structures

77. Vestigial Structures
• Modern animals may have structures that
serve little or no function

78. Vestigial Structures
• Modern animals may have structures that
serve little or no function
– remnants of structures that were functional in
ancestral species

79. Vestigial Structures
• Modern animals may have structures that
serve little or no function
– remnants of structures that were functional in
ancestral species
– evidence of change over time

80. Vestigial Structures
• Modern animals may have structures that
serve little or no function
– remnants of structures that were functional in
ancestral species
– evidence of change over time
• some snakes & whales

81. Vestigial Structures
• Modern animals may have structures that
serve little or no function
– remnants of structures that were functional in
ancestral species
– evidence of change over time
• some snakes & whales
show remains of the

82. Vestigial Structures
• Modern animals may have structures that
serve little or no function
– remnants of structures that were functional in
ancestral species
– evidence of change over time
• some snakes & whales
show remains of the
pelvis & leg bones of

83. Vestigial Structures
• Modern animals may have structures that
serve little or no function
– remnants of structures that were functional in
ancestral species
– evidence of change over time
• some snakes & whales
show remains of the
pelvis & leg bones of
walking ancestors

84. Vestigial Structures
• Modern animals may have structures that
serve little or no function
– remnants of structures that were functional in
ancestral species
– evidence of change over time
• some snakes & whales
show remains of the
pelvis & leg bones of
walking ancestors
• human tail bone

85. Vestigial Structures
• Hind leg bones on whale fossils

86. Vestigial Structures
• Hind leg bones on whale fossils

87. Vestigial Structures
• Hind leg bones on whale fossils
Why would whales
have pelvis & leg bones
if they were always
sea creatures?

88. ANY QUESTIONS??
This is the time to ask…