1. Evolution
Natural Selection – descent with modification. Charles Darwin Origin of the Species by means of Natural Selection
Evolutionary adaptation – increase in frequency of traits that are suited for the environment.
Evolution – genetic composition of the population changes over time

2. Evidence of Evolution
The fossil record – chronology of fossil appearances in the rock layers, marking the passing of geological time. Prokaryotes are the oldest fossils 3.5 billion years ago. (BYA). Fish, Amphibians, reptiles, mammals and birds
Biogeography – geographic distribution of a species. Ex. Australian marsupials

3. Evidences Cont.
3. Comparative anatomy - Comparison between structures of different species
Homologous structures – structures that indicate similar ancestory that have adapted differently through the years. Ex. Whale, bat, cat, human forelimb
Analogous Structures – structures that are used for the same purpose, but are not inherited from a common ancestor. Ex. Butterfly and bird wings
Vestigial Structures – structures inherited from a common ancestor, but no longer used. Ex. Leg and hip bones of a python.

4. More Evidence
4. Comparative Embryology – gill pouches and overall structure in all vertebrate embryos.
5. Molecular Evidence – A,T,C,G exists in all organisms on earth. Gene technology has allowed scientists to compare the genes of different organisms

5. Molecular Evidence

6. Fossil Record

7. Homologous Structures

8. Comparative Embryology

9. Spontaneous Generation
Spontaneous generation – the idea that living things could come from nonliving matter
1668 – Francis Redi – biogenesis – life came from life (meat experiment)
Pasteur’s broth experiment supported this.

10. Formation of the Earth
4.5 to 5 BYA – solar system formed from a swirling cloud of gases and dust with enormous pressure in the center – the sun
Planets formed held by the gravity of the sun.
Earth was probably very cold, with nickel and iron settling to the center and forming the core
Hydrogen gas made up the atmosphere
VERY VIOLENT ENVIRONMENT!!!
Carbon dioxide, nitrogen gas, and methane gas
No ozone layer – lots of UV radiation

11. Early Earth

12. Origin of the first cells
The synthesis of Organic Molecules on early Earth were stimulated by the UV radiation and lightning.
Miller and Urey in 1924 – took water vapor and a mixture of gases and observed amino acids and nitrogen bases ATCG

13. Miller-Urey Experiment

14. Protocells
The first “cell-like” microspheres

15. Early life forms Prokaryotes (bacteria) are the earliest fossils known
These were mostly anaerobic bacteria – live without oxygen
Eventually when oxygen entered the earth, it killed many of these early bacteria.

16. Early Prokaryotes

17. Endosymbiosis
Large bacteria “eats” small bacteria and they become the chloroplast and mitochondria