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WHY EVOLUTION IS TRUE?
Chapter 1 notes:
evolution erodes our sense of self, and our morality
two ideas that completely rejected god: natural selection and evolution
parts of the evolutionary theory:
1.evolution- organisms undergo genetic change overtime depending on pressures
2.gradualism- it takes many generations to produce a substancial change
3.speciation(or splitting)- species split from a common ancestor. The common
ancestor b/w descendant groups is called the “missing link”
- the groups that split can no longer interbreed (unattractive mates, or sterile
- speciation does not happen very often, but when it does, the number of
opportunities for future speciation are doubled!
4. Common ancestory- flip side of speciation, means we have a common ancestor
- mammals and reptiles are joined by having an “amniotic egg” – nested hieracy
-plants and animals fell under “natural classification”
-if speciation is true, then common ancestry is true
5. Natural Selection- survival of the fittest
- wooly mammoth got coolderthose with think hair genes survived, passed
- mutations sometimes lead to the perfect design (rhinos with antlers)
- however brand new features are not made. And so compromises must be made.
- Male testes would be better if outside he body, but they are not, they have
evolved form fish-like testes. Why would intelligent design make us go through
6. Processes other than natural selection can cause evolutionary change- such as
random changes in genes. (genetic drift)
theory of evolution is not just that it happened, but how and why it
happens. Also, it is testable and can make verifable predictions.
Another theory: continental drift caused by plate tectonic found fossils!
Theory of evolution can be supported by evolutionary predictions:
fossil record as evidence for evolutionary change “descent with modification”
speciation should be found in fossil record – splitting of species
species that link, “missing links”, together major groups should be found show
be able to find imperfect designs!
See natural selection happening in the wild
Retrodictions (things that only make sense in the light of evolution): patterns of
species distribution, vestigial features, how organisms develop.
-we only have a fossil record for 0.1-1 percent of all life in all of history
- principle of super position- ordering rocks by age, tells relative age, not
- radio isotopes used too, uranium-235 for older rocks and carbon-14 for
- rocks that bear fossils are sedimentary and harder to date (can be aged by
using adjacent igneous using radioisotopes)
- earth is 4.6 billion years old, corals used to find days and months length
- evolution is not always consistent, sometimes it is irregular like the
- transitional forms: fossils that fill gaps b/w different kinds of organisms,
from bird to humans.
- Creationists believe in microevolution (minor changes) but not
macroevolution (one animals completely changes into another!)
- transitional and ancestral species are not the same. Transitional could be
cousins to the descendants, and they have to appear before and after one of
the species not just b/w the two species, as do ancestral species.
- link b/w fish and amphibians: tetrapods (titaalik) Like fish + amphibian,
could breather with lungs and gills. [transitional]
- how did animals begin to fly? First by gliding flying squirrel & lemur are
-archaeopteryx – dinsosaur had feathers, change from reptiles to birds!
Called a “mosaic”. Then in Chain, another feathered dinosaur was discovered
“S. milleni”, then the 4-winged dinosaur called “M. gui”
- these bird-like dinsosaurs (theropods- even behaved like birds (sleeping)
- wings came from the genes that make scales in reptiles
- wings could have developed b/c of two reasons: ground up theory –
leaping to catch prey, or b/c of the trees down theory- living in trees for
food, escaping predation
- transitional form b/w aquatic and terrestrial: the hippo! spend most time
in water (birth) but can come on land. Release a red oil sunscreen to
- whales have vestigial features, like hind legs, which suggest it came from a
species that lived on land, the closet relative of the whale is the hippo!
- a cousin (not ancestor)of whales- indohyous (partially in water)- similar to
whales b/c it took in oxygen and b/c it had bones denser than land animals
- ambulocetus- “walking whale” then dorudon (closet to whales right now)
- evolution of whales was fast. But why did only some animals go to water,
and not all? B/c when reptile competitors went extinct, the sea was ripe for
- “transitional ant” wasplike and antlike
- Fossils teach us three things:
1. evolution happens!
2. find transitional forms where we should in fossil records
3. evolutionary changes models old into new (not creates new from
ostriches have vestigial wings, that were useful to its ancestor but not anymore.
Still help bird mate, threaten enemies and maintain balance
also other flightless birds: kakpos “parachte” gently to floor of forest. Kiwis have
small wings, hidden behind feathers, have no use. In penguins, wings=flippers.
Vestigial means it is useless for the function for which it evolved.
Wings are not needed when food is found on ground, when you don’t need to fly
(being on an island), and when wings are injured b/c they come in our way (large)
So, natural selection got rid of wings b/c they are metabolically expensive
Eyes are vestigial too, for burrowers, that don’t need them. reduced vision
Why don’t eyes go away completely? Regulate animals bodily rhythym!
Humans have vestigial appendix actually more harmful. But helps immune
system. Our ancestors needing it b/c appendixes break down leaves, we no longer
eat leaves. But, it does not go away, b/c a smaller appendix is more dangerous.
We also have a vestigial tail: coccyx (some useful muscles attach to it)
Another vestigial feature is goosebumps and wiggling ears!
Atavisms- expressed remnants of ancestral features. For example: a horse being
born with an extra toe (come from ancestors with 5 toes, or whales being born
with legs, splint bones in horses are examples of vestigial features)
Atavisms can be made in the lab hen’s teeth. Using mouse tissue. Chickens
have the genes to make teeth, but they are silences.
A gene that doesn’t function (atavism or vestigial) is called a pseudogene.
Most famous human pseudogene is GLO (makes Vitamin C). primates carry
gene to make vitamin c but they don’t. A mutation has caused this.
We also have dead genes from viruses called “endogeneous retroviruses”