BLG 144 Lecture Notes - Lecture 2: Absolute Dating, Special Creation, Time Point
27 Apr 2018
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Background evidence for Evolution
Point 1. Naturalists have noticed species have changed through time
1. Geology – changes in the earth, age of earth, and age of life
2. Fossil record – extinctions and transitional forms
3. Living organisms – transitional forms
Radiometric Dating needs:
1. Observed decay rates of parent to daughter atoms
2. The ratio of parent to daughter atoms present in newly formed rocks
3. Ration of parent to daughter atoms present in a particular rock sample
-Researchers use radioactive isotopes to assign absolute ages to rocks
Vastness of Geologic Time
- Fossils are found in sedimentary rocks, which form from layers of sand or mud
- The layers of these rocks have different intervals in the geologic time scale (a relative time scale
based upon fossil content)
- Earth is much older than 6000 years claimed by proponents of the theory of special creation
according to the geologic record
- Earliest signs of life are found in rocks about 3.4- 3.8 billion years old
- Geologic times are divided into eons, eras, and periods
Extinction changes the species present over time
- Many fossils give evidence to extinct species
- Darwin said extinction was evidence that species are dynamic and species on earth changed
through time
- Fossil records show that over 99% of all species that have ever lived are now extinct
- Data shos etitios hae happeed otiuousl throughout Earth’s histor
- Progressively Older life forms are found in deeper earth layers
Transitional Forms in living organisms Vestigial Traits
- Vestigial trait – a reduced or incompletely developed structure in an organism that has no
function or reduced function, but is like functioning organs or structures in closely related
species ( eg. Human tailbone when we were monkeys, it was used to balance)
- It happens by normal evolutionary processes when the function is no longer needed
- It is also evidence that the characteristics of species have change over time
Point 2. Biologists have figured out that all species are related(to varying extents)
-Molecular Conservation genomics and proteomics
- Homologies - shared ancestry between a pair of structures, or genes, in different taxa)
-genetics, developments, structural, behavioral
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Document Summary
Naturalists have noticed species have changed through time: geology changes in the earth, age of earth, and age of life, fossil record extinctions and transitional forms, living organisms transitional forms. Radiometric dating needs: observed decay rates of parent to daughter atoms, the ratio of parent to daughter atoms present in newly formed rocks, ration of parent to daughter atoms present in a particular rock sample. Researchers use radioactive isotopes to assign absolute ages to rocks. Fossils are found in sedimentary rocks, which form from layers of sand or mud. The layers of these rocks have different intervals in the geologic time scale (a relative time scale based upon fossil content) Earth is much older than 6000 years claimed by proponents of the theory of special creation according to the geologic record. Earliest signs of life are found in rocks about 3. 4- 3. 8 billion years old. Geologic times are divided into eons, eras, and periods.
