Trivia: How long have humans existed on Earth? Hint: the earth has been around for 4.5 Billion years! Life started 3.8 Billion years ago= Life has existed on Earth for 84% of its existence 200,000 years= 0.04% of Earth’s History

Aim: How did life form on Earth?

How did the Earth form? The Big Bang Theory Scientists believe that a huge space explosion created earth and our solar system 14 BILLION Years ago

Earth = 4.5 Billion Years Old

Primitive Earth Poisons & inorganic molecules: No Oxygen !!! Hydrogen cyanide, Hydrogen (H), Methane (CH4), Ammonia (NH3), Carbon Monoxide (CO), Carbon Dioxide (CO2), Nitrogen (N) No Oxygen !!!

Water & Energy Appear Earth cooled & thunderstorms drenched the earth with water, forming the oceans Lightning provided an energy source for life to begin

Organic Compounds Form Lightning sparks reactions with the inorganic compounds, & organic compounds are created!!! C + H Experiment by Stanley Miller & Harold Urey

Organic Compounds – the compounds of life Examples:

Life begins in the Oceans Unicellular, Prokaryotic Anaerobic Heterotrophs The first organisms on earth were simple one-celled organisms

Where did oxygen come from? Some of these early forms of life changed/evolved into autotrophs. Autotrophs: get energy from the sun & make oxygen) The first cells were heterotrophs, anerobic prokaryotes. They had to compete for food so what adaptation would help them survive? By what process do autotrophs make their food? What is given off by the process of photosynthesis? So, now what gas do we have in our environment

Aerobic Organisms Now that the new atmosphere has OXYGEN, aerobic organisms that use oxygen for cell respiration slowly evolved

Eukaryotic Cells Form Single celled organisms in communities joined together to form the more complex eukaryotes

Then life took off in all different directions!

When did Homo sapiens first appear? Human-Like Species Appeared 200,000 years ago http://evolution.berkeley.edu/evosite/evo101/IIE2cHumanevop2.shtml

9 mya: bipedal & climbed trees Humans, Chimpanzees, and Gorillas all have a Common Ancestor: shared ancestor 9 mya: bipedal & climbed trees

Similar to a family tree Descendents Descendents Common Ancestor

Evolutionary Tree – a family tree of organisms Species living at present time (top) Ancestral common species (bottom)

Common Ancestor for all organisms – the first living thing Unicellular Common Ancestor 100’s of Millions of year ago

Determining Relationships Which organisms are closely related? Those who have a recent common ancestor (a close point of intersection in a tree diagram)

What organisms are our closest relatives? Chimpanzees! -share closest branch on tree

Speciation Evolution has lead to the formation of new species from different ancient organisms

How did so many species develop from one common ancestor? Species have changed over time. This is called…..Evolution

Creationism Why is evolution so controversial? Evolution – species change over time Controversy- 1) Science: Theory of Evolution by Natural Selection * Based on Evidence 2) Religion: _____________________ * Based on beliefs Testable! Experiments, evidence! I will give you EVIDENCE to analyze. We can make conclusions based on this evidence. Can’t test with scientific method or provide evidence … You are free to believe! Creationism