1. Happy Thursday (10/16) Write your thoughts on these pictures
Happy Thursday (10/16) Write your thoughts on these pictures. How do they relate to evolution?

2. History of Life on Earth
SB5.b- Students will evaluate
the role of natural selection in the
development of the theory of
evolution.
b. Explain the history of life in terms of biodiversity, ancestry, and the rates of evolution.
c. Explain how fossil and biochemical evidence support the theory.
David A. 10 min Video/Intro

3. History of Life on Earth
Began approximately 4.6 billion years ago
Current speculations on formation of Earth
Cosmic debris collected and cooled
Planet experienced constant volcanic and geological upheaval
Anaerobic (no oxygen)
Finally began to cool and form liquid water
The origin of life, followed by a whirlwind tour of the past 4.6 billion years of history.
Starting from the beginning, as it is currently thought of: the Universe came into being about 15 billion years ago, with the sudden appearance of all the matter and energy in the Universe as a single very hot and dense point: the Big Bang. How this happened, and what came before, is a matter of complete speculation. Our history began then, and we have no scientific evidence of anything before then.

4. Origin of Life: Prokaryotes
Most popular theory
Life first appeared a few million years after formation of Earth
First organisms prokaryotic
Select prokaryotes began to create oxygen
This created aerobic atmosphere
We don’t know how life originated.
Probably arose on Earth, but an alternate theory suggests it arose elsewhere and drifted through space to seed the Earth. Note that it still had to originate somewhere.
What does life need? A way of harnessing energy to do useful work, a way of storing and reproducing genetic information, a way to keep the inside separated from the outside.
Which of these arose first is a matter of debate. Inheritance first or metabolism first? Or both simultaneously?
However, once a genetic system is in place, natural selection will quickly improve the new life form.
After Earth formed and began to cool, Scientists belive prokaryotes evolved. What are prokaryotes? (single cell organisms with no nuclues). What are modern day examples? (bacteria). These bacteria would have had to live in extreme environments; no oxygen and volcaninc.
Scientsist belive oxygen was absent on earth until 1.8bya. The first oxygen was most likely created by prokaryotes. Oxygen began to saturate the planet. These prokaryotes probably underwent the process of photosynthesis (cyanobacteria). This oxygenation of the atmoshphere allowed for the next type of organisms to develop.

5. Origin of Life: Eukaryotes Eukaryotic cells appeared approximately 1
Origin of Life: Eukaryotes Eukaryotic cells appeared approximately 1.8 billion years ago
Endo- symbiotic theory
Ancestors of eukaryotic cells lived in close proximity to bacteria and algae cells
The ancestral eukaryotes formed a symbiotic relationship and became incorporated into the bacteria and algae cells
Eukaryotes first appeared 1.8BYA in the fossil record. This is approx 2 billion years after life began on earth. What is a eukaryotic cell? (has nucleus and membrane bound organelles). So how did Eukaryotic cells arise? One theory is called the Endosymbioiont theory. The Eukaryotic ancestors lived in close quarters/proximity with prokaryotic organisms. Some eukaryotic ancestors may have lived inside of prokaryotic organisms. This relationship would have been symbiotic or mutually beneficial for both organisms. Think back to 7th grade, what did we call relationships that were beneficial to both organisms (mutalistic). Scientists believe this process is what led to our present day chloroplasts and mitochondria in eukaryotic cells.

6. Origin of Life: Eukaryotes cont.
Eukaryotic organisms continued to evolve
Sexual reproduction began
Increased genetic variation
New organisms developed
Gave rise to multi-cellular life
As time progressed Eukaryotic organisms became more numerous. Some began to reproduce sexually. What do you need to have to reproduced sexually (egg and sperm; both haploid). And why is sexual reproduction so adventagous? (greater genetic diversity). This diversity led to the development of new organisms. And over time gave rise to multicellular life. Multicellular means: (2> cells).
These fossils (on bottom) are 2.1byo and are some of the earliest known example of complex life on Earth. Have yest to classifified. Were either complex colonies of single-celled organisms, or early animals. Found in 2010.
Recap:
First organisms: Prokaryotes
Prokaryotes are… unicellular
These prokaryotes would have resembled what modern day organisms?.... Bacteria
Now, how do scientists believe eukaryotic organisms rise: From a close relationship between 2 prokaryotes
As eukaryotes began to evolve, some began to reproduce sexually; this allowed for…. Genetic variation, development of new organisms and multicellular life.

7. Geological Time Scale Represents the evolution of biodiversity
4 eras: Precambrian, Paleozoic, Mesozoic, and Cenozoic
Each era is broken into periods
People who study the history of earth are called paleontologists. They use a geologic time scale to represent the evolution of biodiversity. The time scale is broken into 4 eras: Precambrian, Paleozoic, Mesozoic, and Cenozoic. The eras are further broken into periods. What can paleontologists use to study past life? Fossils.

8. Precambrian Earth formed and first life appeared
Emergence of autotrophic prokaryotes (cyanobacteria)
Appearance of simple eukaryotes
Sexual reproduction begins
Multi-cellular organisms appear
Sponges, cnidarians, and annelids
Note: All life is aquatic!!

9. Paleozoic Era 543 Million Years Ago
Cambrian explosion
relatively rapid appearance, of most major animal phyla
Approximately MYA, life on land appeared
Mass extinction occurred at end of this era (252 MYA)
Wiped out 90-95% of aquatic life, 60-70% terrestrial life
Permian extinction: The largest mass extinction event in Earth’s history.
Large lava eruptions in Siberia followed by widespread glaciers. Volcanic dust in the atmosphere lowers temperature drastically. Possibly caused by an impact?
May have triggered a buildup of hydrogen sulfide (produced by bacteria) in the atmosphere that displaced most of the oxygen.
May have caused the release of vast quantities of methane from methane hydrate deposits on the ocean bottom. This greenhouse gas might have raised the Earth’s temperature enough to kill most life.
95% of all species die out.

10. Mesozoic Era 248 Million Years Ago
Mammals, dinosaurs, birds and flowering plants appear
Dinosaurs dominated
End of era meteorite hit near the north coast of the present-day Yucatan
75% of life goes extinct
Nothing above 25kg (55lbs) survive
Some survive meteorite, but die to changing climate after impact

11. Pangea Pangea was a supercontinent
Plate tectonics helped to change the environment.
Caused drastic geological changes throughout the Mesozoic era into the Cenozoic era
Plates began to drift apart
Allowed for new species and environments to form

12. Cenozoic Era 65 Million Years Ago to Present Day
After the mass extinction, mammals began to diversify into distinct groups
500,000 years ago Homo sapiens and Neanderthals lived
65,000 years ago Neanderthals die out
Started 65 million years ago, continues to present.
Mammals become the dominant life form on land. An adaptive radiation that took advantage of the sudden loss of dinosaurs.
Another large group evolves: the grasses.
Adaptive radiation of birds and flowering plants.
Fishes and reptiles don’t change much during the Cenozoic.
Geologically, continents that had been separated started to collide: Africa with Europe, North America with South America, India with Asia
There existed two major hominid species about half million years ago - the Homo sapiens neanderthals in Europe and the Levant (see Figure 18), and the Homo sapiens sapiens (see Figure 19) in Africa
Anatomically Modern humans (AMH), who emigrated from Africa about years ago, may have slaughtered the Neanderthals. Eventually, around years ago only one species, Homo sapiens sapiens, was left.

13. Quick Recap https://www.youtube.com/watch?v=ZSt9tm3RoUU
Life in 1 minute
Mr Parr Eras song

14. Fossils Study of fossils is called paleontology
Fossils are the remains of once living organisms found in the rock layers of earth
Found in sedimentary rock
Fossils are used to establish relationships among extinct and existing organisms
Most organisms decomposed before they could fossilize
Many fossils are just impressions of an organism
If organisms were rapidly buried in sediment then they would fossilize

15. Fossil Record
Show evidence of evolution by providing “snap shots” of ancient organisms
Used to create evolutionary charts to show how modern day organisms evolved
Ancestry is the history of an organisms development

16. How Old Are Fossils? Grand Canyon
Where are the oldest rocks found? (Towards bottom). What are the lines/strata indicate? (different layers of rock at different time periods). The comparison of the rock layers (older and newer) is called relative dating.
Rocks are made of different chemical elements. They break down over time, thus forming other elements. Some of the elements are radioactive, and break down at a constant rate. So when you measure the radioactive elements against the non, you can determine radioactive dating.

17. Now for a song… https://www.youtube.com/watch?v=RNSrNT-nIDE
Mr Parr
Fossils Rock Anthem