1. INTRODUCTION TO EVOLUTION
UNIT #5 EVOLUTION

2. Evolution Change in genetic composition over time
“Descent with Modification”

3. Darwin’s Influences Aristotle (384 – 322 BCE)
Viewed species as fixed (unchanging)
Believed that life-forms can be arranged on a ladder
Scala Naturae (Scale of Nature)
His ideas were consistent with the Old Testament
Species were designed by God (therefore perfect)
Species were created by God for a particular purpose

4. Darwin’s Influences Carolus Linnaeus (1707 – 1778)
Worked “for the greater glory of God”
Developed the two-part (binomial) format for naming species
Homo sapiens – Humans
Adopted a classification system grouping similar species into increasingly general categories
Same Family
Same Genus

5. Fossils
Darwin also gained many ideas from scientists that studied fossils
Fossils – remains or traces of organisms from the past
Found in sedimentary rocks from the sand and mud
New layers of sediment cover older ones compressing them into super-imposed layers of rock called strata
As time passes, erosion carves through upper (younger) strata revealing deeper (older) strata that had been buried
Paleontology – the study of fossils

7. Darwin’s Influences Georges Cuvier (1769 – 1832)
Noticed the older the stratum (layer), the more dissimilar its fossils were to current life-forms.
Observed that from one layer to another, some new species appeared while others had disappeared.
Inferred in the idea of extinction, while opposing to the idea of evolution
He believed that each boundary between strata represented a catastrophic event

8. Darwin’s Influences James Hutton (1726 – 1797)
Hutton proposed that Earth’s geographical features can be explained by slow and gradual mechanisms
Charles Lyell (1797 – 1875) incorporated Hutton’s thinking into his proposal
He believed the same geologic processes are occurring today as in the past, and at the same rate
Hutton and Lyell’s ideas influenced Darwin into thinking that geologic change occurs through slow, continuous actions rather than sudden events
Led Darwin to believe that Earth is more than thousands of years old .

9. Darwin’s Influences Jean Baptiste de Lamarck (1744 – 1829)
Proposed a mechanism for how life changes over time
He is not remembered for his recognition that evolutionary change explains patterns in fossils and the match of organisms to their environments
Remembered for the incorrect mechanisms that he proposed
Found what appeared to be several lines of descent
Each in a chronological series of older - younger fossils - present- day species

10. Darwin’s Influences Jean Baptiste de Lamarck (1744 – 1829)
He explained his findings with two principles that were widely used at the time
Use and Disuse - belief that parts of the body that are mostly used become stronger and larger, while those that are not used start to deteriorate
Inheritance of Acquired Characteristic - an organism can pass these modifications to its offspring
He believed that evolution occurred due to an organisms desire to become more complex (rejected by both Darwin and Cuvier)