Transcript Evidence of Evolution

Evolution
The Evidence
‘Evolution’ stands for several theses:
• Mutability of species (i.e. species change over time)
– (observed/confirmed)
• Natural selection
– (observed/confirmed)
• Community of descent (i.e. all life forms share a common
evolutionary history ; all forms are related by descent)
– Including humans and chimpanzees; humans and fish;
humans and turnips; humans and bacteria
– (inference; but based on diverse and compelling evidence)
– (indirectly observed/indirectly confirmed)
Evidence for evolution
1. Fossil Record
2. Vestigial Structures
3. Skeletal Homologies
4. Embryological Homologies
5. Cellular Homologies
6. Genetic Homologies
7. Imperfect Design (Dysteleology)
8. Observed instances of origin of new species
Fossil record
Archaeopteryx, dinosaur-bird transition
Fossil record
Tiktaalik rosae, fish-land vertebrate transition found Canadian
Artic 2004
Vestigial structures
Vermiform appendix
Vestigial structures
Hand bones
Skeletal homologies
Embryological homologies
Haeckel 1874
Embryological homologies
Richardson et al 1997
Cellular homologies
Genetic homologies
1. All living things use same genetic code: DNA,
RNA
2. All living things employ same 20 amino acids
to form proteins
3. All living things use only right-handed
molecules
4. Homologous proteins and genes found in
organisms as widely different as humans,
fruitflies, tulips, brewers yeast, and bacteria
Genetic homologies
Human-chimp 98% overlap
Same base-pair errors occur in human & chimpanzee pseudo-genes:
Coincidence?
Missing Human Chromosome Pair
If humans and other apes evolved from a common ancestor why do we
have only 23 chromosome pairs to chimps’ 24?
Tinkering
Dysteleology (poor design)
Dysteleology (poor design)
Dysteleology (poor design)
Dysteleology (‘tinkering’)
Dysteleology (‘tinkering’)
• Eukaryotic cells (like
ours) a symbiotic
merger of several
previously independent
prokaryote bacteria
• Mitochondria (animals)
• Chloroplasts (plants)
• Centrioles, nucleus too?
Poster child of tinkering
Symbiotic merger of at least 4 separate organisms; 5 counting mitochondria
Have we ever observed the origin of
any new species?
• First, what do we mean by a species?
• Morphological species concept: based on
observable body shape, size, markings etc.
• Reproductive species concept: two organisms
are of the same species if they can
successfully produce fertile offspring
Origin of new species observed
Polyploidy = chromosome # increase (genome
doubling etc.; common in plants; but also seen in
amphibians, fish)
Origin of new animal species observed
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Fruitflies
Mosquitoes
Cichlid fishes
Amoeba-bacteria
symbiont