Evidence for Evolution and Common Descent - student notes
Natural selection notes
Make sure your check out the evolution links for lots of background info | Check out this
site for an excellent overview of evolution | Also check out the PBS evolution site for lots of
good basic info
The textbook covers evolution in chapter 13 (natural selection)); 14 (speciation); and 15
(fossils/history of life)
I. Definitions: (click for more details)
A. Change over time
B. Cosmic Evolution: the Big Bang - theory that explains how the universe was
created (how it happened, not why or who) (this theory in no way conflicts with
Genesis, but for some reason a lot of people think it does) (how do we know how
big the universe is??) (more on the evolution of the universe and stars)
C. Chemical evolution: the origin of life (how it started, not how it has evolved
since) (check out some recent research)
D. Biological evolution: Natural selection - theory that explains how species can
change over time in response to environmental changes; involves survival of the
"fittest" individuals or genes
E. Biological Evolution: Common descent/ancestry - theory that all living
things share a common ancestor - presumably a one-celled creature of some sort.
It is usually postulated that new species arise over time through natural selection,
and that over very long periods of time the vast diversity of living things was
produced. (click here for the latest version of the "tree of life")
F. Evolutionism (evolutionary philosophy) is a belief that physical explanations
provide all of the answers about life; that there is no God. (similar to atheism or
naturalism)
G. Social darwinism is a belief that "survival of the fittest" should be applied to
society, and that we should not allow "weaker" or "inferior" members to
reproduce. It is not believed by many people today, although it was widely held in
the early 1900's.
Timeline of evolution-related discoveries and events
II. Natural Selection
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first proposed by Charles Darwin in 1859 in "On the Origin of Species", and also by
A.R.. Wallace around the same time (Darwin’s voyage – p. 256-257)
A. The theory is based on several observations about the way the creation works: | check out this
background activity: how evolution works
1. overproduction of offspring
2. competition for limited resources
3. individual variation - some individual have genes/traits that allow them to
survive longer, sometimes called adaptations (see p. 270)
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example - snails
there is considerable debate about whether mutations can be helpful
As a result of these three situations, the following results:
4. the individuals with the "better" traits will live longer, have more offspring, and
pass on their traits
5. over time, the frequency of the favored trait increases
B. Examples of Natural Selection that do not involve new species:
1. industrial melanism – moths in England – (check out why this is a good
example)
2. pesticide resistance (more) (see fig. 13.3, p. 259)
3. antibiotic resistance (view animation of this process and another animation)
(overview of the problem - CDC)
4. sickle-cell anemia
5. changes in salmon size as a result of fishing
6 forest vs. savanna elephants
7. the multiple varieties of dogs are a results of artificial selection
8. many examples involve co-evolution, where one species evolves in response to another
| more on co-evolution
9. evolution in action - crickets in Hawaii - 2008 study
10. Fish in the Hudson River have evolved resistance to PCBs, industrial chemicals that
were dumped there for decades by GE
C. speciation refers to the process of a new species being formed | more here - evidence for how
speciation works | and here - basic overview
In order for new species to form, the population usually must be separated into two groups. Over
time, they evolve differently, until they can no longer interbreed
D.. adaptive radiation refers to the development of several new species from a common ancestor
after colonization of a new area, or after a major extinction (see fig. 14.10 p. 288 and
15.10). Following are examples of speciation, some of which are also considered adaptive
radiation.
a. Cichlid fish in Lake Victoria (more)
b. shell fish in inter-tidal zones
c. rainforests – adaptive radiation of insects, rodents, etc.
d. arctic char in an Iceland lake
e. plants
f. observed examples of speciation -- talk.origins faq
g. directional vs. stabilizing selection
h. species on islands are often larger or smaller than their mainland counterparts
i. salamanders in California - (other examples of "ring species") (a good article
explains how this works)
j. finches in Galapagos – p. 287, fig. 14.9 and p. 288, fig.14.10
k. animation of natural selection
Check out an illustrated explanation of how new species can form - this is
called allopatric speciation
E. Geographic separation can lead to reproductive isolation:
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sexual selection -- preference for size, color, etc.
o more examples -- "The importance of being flashy"
o the Irish elk -- huge antlers considered an example of "runaway
sexual selection"
o see fig. 13.14
parasites
timing of mating
size/shape changes
hybrid sterility (p. 281, fig. 14.3C)
changes in chromosome number (examples - tree frogs and plants)
see table 14.3, p. 280; examples of barriers p. 280-281
example of geographic isolation -- p. 282-283, fig. 14.4 and 14.5
hybridization can cause speciation to "run in reverse"
F. some changes do not result from natural selection – p. 268
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1. genetic drift
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2. bottleneck – fig. 13.11
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3. founder effect
G. evo-devo: developmental changes can drive major evolutionary changes. More here.
a. macroevolution refers to large-scale changes, such as the evolution of wings
b. Does evolution have goals? p. 307 - fig 15.13 – horses
c. scientists debate the pace of evolutionary change by comparing the gradualist
and punctuated equilibrium models. Many scientists propose that the
environment plays a significant role in the evolution of species, especially in the
case of mass extinctions (such as the asteroid that may have killed off the
dinosaurs; also a mass extinction at the end of the Permian period)
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debate on the tempo of evolutionary change – p. 289
dinosaur extinction – p. 302-303
H. The gene pool of non-evolving populations remains constant over time -- see p. 266-267 Hardy-Weinberg equilibrium
I. Natural selection can shift gene frequencies in three ways -- see p. 270, fig 13.13
1. Stabilizing selection
2. Directional selection
3. Diversifying selection
J. Kin Selection
III. Common Descent and the history of life (chap 17) | check out evidence for evolution |
more evidence here (plus all the links below)
Common descent: the theory that all creatures are descended from a common ancestor. (This
theory is not the same thing as natural selection and was not invented by Darwin)
A preview of the Categories of Evidence:
A. Fossils and the history of life
B. Biogeography patterns
C. Similarities between creatures
Darwin's predictions - evidence for common descent
A. Biogeography - see p. 301
1. definition: study of the differences between similar species in differing
geographic locations
2. species on islands differ from those on mainland (background information)
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Madagascar | another site and still another |
new tree species | another Madagascar site
Galapagos (another site) (still another) (and
yet one more!)
Hawaii
o what makes it unique
o hundreds of species of fruit flies
Australia and New Zealand
Island species are often smaller or larger than
their mainland counterparts | more here
Catalina Island, southern CA
3. species on one side of a continent differ from those on the other side (example white-tail deer and mule deer)
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more info
4. species on different continents are different, but fossils show that species on
different continents used to share the same range. (ties in with continental drift)
· plants in Australia, South America, Africa, and Antarctica
· fate of marsupials on South America
Examples of speciation based on biogeography (some new species have evolved,
but this does not necessarily prove common descent of all creatures):
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Cichlid fish in Lake Victoria | more on Cichlids
more listed with the natural selection section
B. Similarities between species
1. extensive similarities are often found between limbs or organs of similar
creatures
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check out these comparisons of human and gorilla skeletons
similarities between limb bones of tetrapods
compare wolves, dolphins, and fish
compare the skeletons of humans with chimpanzees and extinct homonids
2. homology and analogy (click for a good explanation) (fig. 15.14, p. 308):
a Galapago finch
a. homologies are structures that share a common origin but not
necessarily a common function
examples: reptile jawbone and mammal inner ear bones; and the swim
bladders and lungs; “animal hands”
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Convergent evolution (analogous structures develop more than once)
Examples of convergent evolution | the Tasmanian "tiger"
postulated ancestry of whales (more here) | and here
fossil snake with hind legs
3. comparison of protein sequences and DNA sequences between various
organisms
a. similarities often parallel the anatomical similarities – human
proteins are more similar to monkeys than to lizards, for example.
b. pseudogenes, gene duplication and divergence, and exon
shuffling help explain genetic changes
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"pseuodgenes" and other genetic sequences
exon shuffling
example
gene duplication
c. The rate of mutation can be used as a “molecular clock”
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it is assumed that mutations happen at a regular rate, and
thus the number of differences between two genes (in
different species) tells how long ago they shared a common
ancestor (see 15.8, p. 313)
4. Patterns of development
a. development is the process of growth from fertilization to adult.
It usually refers to animals.
b. patterns are often similar in the early stages. Structures not
found in the adult will appear and then disappear. (note examples
below)
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vestigial structures, such as the pelvis
in whales
pharyngeal "gill slits"
kidneys
major blood vessel connections
some of these similarities can be seen
in the embryo drawings show here.
(This drawing from newer edition of the
honors text. Our version has the older diagram
based on 19th century work by Haekel; it
turns out that he "forged" his drawings a bit to
make them look more similar. These drawings
are more accurate. For more info check out
this link)
c. recently, evidence has shown that small genetic changes can
cause major developmental changes, and might help explain the
formation of new species with new features. For examples, see:
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This image is from a recent study
that showed a genetic change could cause the loss of legs in
arthropods.
Learn more about the relationship between evolution and
development
Macrodevelopment is a new theory from a pair of Christian
biologists. The theory suggests that new types of creatures
form by major developmental changes, rather than natural
selection.
criticisms: Mike Behe says that sequence comparisons do not establish how complex structures
such as eyes could have evolved. examples. He calls this concept "irreducible complexity"
C. Fossils and the history of life – p. 299
1. life has changed over time - we can tell by
interpreting the fossils
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a brief history of life
the Tree of life
Explore fossil research
this is a fossil
shrimp
2. how are fossils formed and interpreted?
a. formation - rapid burial in sand, mud, tar, etc. Hard parts are
most often preserved; also impressions of soft parts
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more background info on fossils
amber (link to NOVA website: Jewel of the Earth)
learn how fossils form and are buried
b. dating the fossils
· relative dating (position in rock layers)
· radioactive dating (p. 298 - fig 15.5)
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Overview of geologic time
another overview
animated explanation | another animation |
still another animated explanation
another overview from a Christian
perspective
Radiometric Dating: a Christian Perspective
c. studying the fossils involves careful comparison of various
features
3. geologic periods - the time table gives us a general progression of when
different species lived when went extinct. (p. 299, table. 15.6)
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Interactive tour of Geologic time
Animated timeline of the history of life
Timeline with pictures and background info (American Museum of
Natural History)
Timeline with illustrations of sample creatures
Triumph of Life - timeline with photos of representative creatures
Geological time machine -- links to details on geological eras
Timeline with emphasis on evolution
Major events in the history of life (interactive)
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History of the universe (interactive)
there were many coral reefs in the Silurian era
4. Continental drift – p. 300-301, fig. 15.7
5. most major complex kinds of animals (phyla) appeared early and have changed
little since that time. This happened during the so-called "Cambrian explosion".
(scroll down to learn more)
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the Burgess Shale fossils represent interesting and (some)
unique creatures from the time of the Cambrian Explosion
more on the Burgess shale -- this one with photographs of
the fossils
6. there have been 5 major extinctions, but the overall diversity of life has
increased
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Blast from the past - evidence for the Asteroid theory of
dinosaur extinction
7. "transitional forms" between major groups
a. there is some debate about how common transitional species are
b. examples of some transitional forms can be found at these web
sites:
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overview of the fossil record
The American Museum of Natural History has a site
that explains the supposed transitions between major
groups of reptiles and mammals
Transitional Fossils section of the Talk Origins site
reptile-bird and reptile-mammal transitions
fossil mammals
a discussion of the transition from fish to amphibians
Hallucigenia -- an extinct creature fr
Cambrian period
The Illinois State Museum has a good site that explains
the effect of the ice ages on recent extinctions. They also
have pictures of extinct mega-mammals from before the
last ice age.
Virtual Paleontology Museum
Dinolab - a great site about dinosaurs
Fossil Horses in Cyberspace -- pictures/info on horse
fossils
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Paleontology museum at Cornell -- check out images and
information on invertebrate fossils.
This page, produced by a Christian geologist, explains the
purported transitions between fish and amphibians.
hind legs on a whale??
more on whale origins (Nov 2001 Nat. Geographic)
origins of bird flight
Compare modern humans with Neanderthals
The famous "Piltdown man" hoax
overview of 5 significant transitional fossils
simulations of dinosaurs and other prehistoric life
(interactive site from BBC)
4-winged dinosaur - a possible dinosaur/bird transition
This image is of Archaeopterix, a fossil thought by
some to represent the transition between reptiles and
birds.
8. transitional forms are more common within similar groups (e.g. good evidence
that all bears had a common ancestor)
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read an analysis of the Cambrian explosion by Christian geologist Glen Morton (in the
last five years, more fossil finds have suggested that pre-Cambrian ancestors for some of
the phyla may exist)
view an animation of the Cambrian explosion
IV. History of life - some relationships | see BBC's gallery of prehistoric life | walking with
prehistoric beasts | more links below | see also chap 19
A. Modern species are not considered ancestors of other modern species.
B. Fish appear in the fossil record before other vertebrates. They are presumably
ancestors of other vertebrates
C. The first 4-legged creatures (tetrapods) were amphibians
D. Reptiles appear next. Birds, dinosaurs, modern reptiles, and mammals are all
considered descendents of extinct reptiles.
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click here for the latest version of the "tree of life", as proposed by
common descent theory)
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basic overview of evolutionary "family trees"
What is a dinosaur? | learn more about dinosaurs
Human evolution - compare a human skull to H. Florensis, the "hobbit"
fossil found recently in the South Pacific | more on the Floris fossils
Human evolution - gallery of fossil evidence | overview from PBS |
overview from Evolution 101
More on human evolution | New fossil specimens called "Ardi" are
possible human anscestor
The American Museum of Natural History site explains the current
theories on transitions between major groups of reptiles and mammals |
see also overview of palenotology from the American Museum of Natural
History | exhibit on human origins | vertebrate evolution
Smithsonian Institute: top 10 misconceptions about dinosaurs | pictures of
the Burgess Shale fossils, which date from the Cambrian Explosion
UCMP Berkeley -- paleontology museum: the history of evolution
(Darwin was not the first one to talk about it!) | overview of the latest
theories about relationships between organisms (a family tree of sorts) |
The Cambrian Explosion refers to the simultaneous appearance of most
major animal phyla, including fossils from the Burgess Shale | featured
site on the Origins of Bird Flight
The Illinois State Museum has a good site that explains the effect of the
ice ages on recent extinctions. They also have pictures of extinct megamammals from before the last ice age -- such as ground sloths.
video - tracing the history of life
Paleoportal - explore fossils and the geological time scale
Explore the origins of human anatomical features
Whale evolution
E. Most paleontologists believe that birds evolved from a group of dinosaurs called
Theropods
How will life evolve in the future? Check out the Future is Wild
V. Interpreting Evolution from a Christian perspective
A. God’s revelation to us comes in two forms
1. General revelation – the creation (see Ps. 19:1-4)
2. Special revelation – the Bible
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These two forms of revelation cannot disagree. When there are apparent
disagreements, they result from our theology or our science being wrong.
See diagram for more explanation
B. God works in two ways
1. Supernatural (miracles)
2. Natural
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we must view God’s action in both natural and supernatural – in
opposition to Deism
God is creator and sustainer (see Ps. 104:27-30)
C. Christians have taken several approaches to resolving the conflicts.
1. overview of seven different positions | another version
2. Young-earth creation
3. Old-earth creation/Progressive creation
4. Theistic evolution/evolutionary creation
5. Intelligent design
D. Framework approach to understanding Genesis 1
1. God forms on days 1-3 and fills on days 4-6
2. The progression of events is not necessarily literal – it was written to inform us
about the nature of God’s creation and our relationship to the rest of it