EVOLUTION Flashcards
Theory
- Every day language = educated guess
- Sciences = explanatory model that accounts for a very large body of evidence
- Scientific theories provide basis for explaining observations of the natural world and for making testable predictions
Evolutionary Theory (general)
- All life forms are fundamentally similar at cellular and molecular level
- Evolution explains the history of life on earth
- Evolution is the process by which organisms change over time
Evolution of Evolutionary Theory
(important people)
Aristotle (384 - 322 BCE)
Georges-Louis Leclerc de Buffon (1707-1788)
Carl Linnaeus (1707-1778)
Erasmus Darwin (1731-1802)
Chevalier Lammark (1744-1829)
Charles Darwin
Early Theories: Aristotle
- Most Europeans accepted the idea that all living things had been created in their present forms and were immutable
- They could not change and had not changed
- All natural phenomena developed through strongly held religious beliefs
Early Theories: Buffon
- Applied scientific methods to the detailed study of anatomy
- Studied animal structures
- Considered their functions
- Puzzled by some features that seemed to have no purpose
- E.g. he studied pig toes, they have toes that don’t reach the ground
Evolutionary Theory: Linnaeus and Erasmus Darwin
- Proposed life changed over time
- Erasmus (Charles Darwin’s grandfather) suggested life might have evolved from a single original source
How old was the world originally thought to be, and what contradicted this belief?
- Scientists thought would was 1,000 years old
- Scientists began to find fossils, which contradicted this belief
Fossils
Any ancient remains, impressions, or traces of an organism or traces of its activity that have been preserved in the Earth’s crust
* Fossils dated back to minimum age of 1,000 years
Preserved materialized remains of organisms
* The closer to the surface, the more recent the ancestor
* Organisms die and become trapped in sediments
* Fossilization is a comparatively rare event
* Fossil record is incomplete
Palentology
Study of fossil organisms to learn about prehistoric life
* Cuvier (1769-1832) was a paleontologist
Geology
Study of the Earth’s physical structure
* Lyell (1797-1875) was a geologist
Cuvier
Through study of paleontology, noted the following:
* Fossils of very simple organisms are found in all depths of fossil deposits
* Fossils of more complex organisms are found only at shallow depths in younger rock
* Fossils in shallower depths are more likely to resemble living species
* Rock layers contain fossils of many species that do not occur in layers above or below them
Catastrophism
- Fossil observation offered strong support that life evolved from simple to complex
- Cuvier believed that species themselves didn’t change
**Catastrophism **= global catastrophes, such as fossils, caused the widespread extinction of species
* Cuvier believed these speicies were then replaced w another newly created set of species
Uniformitarianism
- Charles Lyell (father or modern geology)
- 1830 - put forth his theory/principles of uniformitarianism
**Uniformitarianism = **
* Earth has been changed by same processes in the past that are occurring in the present
* Geological change is slow and gradual, rather than fast and catastrophic
* Natural laws that influence these changes are constant and eternal, they operated in the past w the same intensity they do today
* Lyell’s theories directly challenged belief in a young Earth (1,000 years old or less)
Evolutionary Theory: Lamarck
- Student of Buffon
- First scientist to offer a mechanism for the evolution of a species
- Evolutionary change resulted from two distinct principles:
- Use and disuse
- Inheritance of acquired characteristics
Lamarck’s First Principle: Use and Disuse
Structures an individual uses become larger and stronger while structures not used become smaller and weaker
* E.g. athlete’s muscles increase in size (structures in use), astronauts returning home have reduced muscles from lack of use (structures not in use)
Lamarck’s Second Principle: Inheritance of Acquired Characteristics
Individuals pass down characteristics acquired during lives
* E.g. if adult giraffe stretched its neck during its lifetime, then its offspring would be born w slightly larger neck
Lamarck’s Findings
Though Lamark’s theory was flawed, he made significant contributions to our understanding of evolution
* All species evolve over time
* A species evolves in response to its environment and becomes better adapted to that environment
* E.g. bunnies fur turns white in winter, helps blend in w snow and hide from predators
* Changes are passed from generation to generation
Charles Darwin
- By the 19th Century, there was growing evidence that Earth was old
- Ideas of the history of the Earth and its life-forms were being challenged
- Charles Darwin linked ideas from paleontology, Geology, geography biology, and his own observations to come up w a mechanism of evolution: Natural Selection
Who was Charles Darwin
- Born in 1809 in Shropshire, England
- Son of a local doctor and wedgusod heiress
- Parents wanted him to study medicine
- Found more interest in natural word
Voyage of the HMS Beagle
In 1831 at 22, Darwin set sail on HMS Beagle for a 5 year trip to record and collect specimens for the British Navy
* They had hoped that Darwin would find evidence of biblical creation
On his voyage, Darwin:
* Collected thousands of specimens
* Collected fossils that resembled existing animals
* Volcanic Galapagos Islands had species similar to South American natives
* Made most discoveries in galapagos
* Species differed from island to island
Patterns in Diversity
- Species vary globally: species varied depending on where they lived on Earth
- Species vary locally: species had different features depending on local habitat
- Species vary over time: species evolve from one common ancestor
- Become different creatures over time
- Geological change
