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Evidence for Evolution
Human Biology and Forensics
January 7, 2014
Evidence for Evolution
• What do we know about evolution
– Change in species over time
– Darwin explained using Natural Selection
– Natural Selection: Individuals with traits that are
more favorable in a particular environment are
more likely to survive and reproduce
– NeoDarwinian Evolution also says that Mutation,
Gene Flow and Genetic Drift contribute to
evolution
This Unit: Evidence for Evolution
• This Unit:
– Forms of evidence of evolution
– Hominid Traits
– Different Types of Hominids
– Phylogenies
– Phylogeny Project
What evidence is there for evolution?
• There are lots of forms of evidence for
evolution:
– Comparative Anatomy
• Homologous Structures
• Vestigial Structures
– Embryology
– Biogeography
– Comparing Macromolecules
– Fossils and Law of Superposition
Comparative Anatomy
• Evolution is a continuous process and by
examining genotypes and phenotypes in
modern organisms we can see that evolution
has occurred
• Since organisms change through a process of
gradual modifications we can see evidence of
their evolutionary history
Homologous & Analogous Structures
• Homologous features are similar features that
are found in organisms that share an
evolutionary relationship
– Wings in Eagles and wings on a chickadee
– Opposable thumbs on monkeys and humans
– Forelimbs: penguin, alligator, bat, human
Homologous & Analogous Structures
• Analogous features have identical functions
and look alike
• Have different embryological development
and may have different internal anatomy
• No evolutionary relationship
• Bird and insect wings
Vestigial Structures
• These are structures with no useful function
– Human tail bone, appendix
– Whales with pelvic bones; limb bones in snakes
• Features were useful to ancestor but not
useful today
• Understand
evolutionary past
Embryology
• Early stages of vertebrate embryos are similar
• Ontogeny recapitulates phylogeny – embryo
development repeats evolutionary history –
gills and fins
Biogeography
• Study of distribution of fossils and living things
• Organisms are compared with fossils in the
area; similar in forms
• Modern kangaroos only live
in Australia where the
extinct giant
kangaroo lived.
Similarities in Macromolecules
• More similar forms of organisms have a more
recent common ancestor than less similar
forms
• Compare proteins, DNA and RNA molecules
Similarities in Macromolecules
• Amino acid sequences in hemoglobin are
similar but not identical
– Humans and gorillas differ by one amino acid
– Humans and frogs differ by 67 amino acids
• The more time passed, the more differences
between amino acid sequences; more amino
acids shared the more recent they were
Fossils
• Fossil is a trace of a long-dead organism
• Usually in rock when sediment is deposited by
wind and water
• Develop from hard parts of body (teeth,
bones, etc.)
Fossils
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Hard mineral replace organic tissue
Molds are imprints of living thing
Cast are rock like models of organisms
Mosquitoes trapped in amber are fossils,
footprints, tracks
Law of Superposition
• Layers of soil get deposited on top of each
other; Lowest layers are oldest and top are
youngest (stratum)