1. THE HISTORY OF LIFE EARLY HISTORY OF EARTH EVIDENCE
HOW OLD IS SOMETHING?
WHAT IS GEOLOGIC TIME?
FIRST CELLS
ENDOSYMBIONT THEORY
Courtesy NASA/JPL-Caltech
Modified by JO from Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

2. THE HISTORY OF LIFE EARLY HISTORY OF EARTH EVIDENCE
HOW OLD IS SOMETHING?
WHAT IS GEOLOGIC TIME?
FIRST CELLS
ENDOSYMBIONT THEORY
Courtesy NASA/JPL-Caltech
Modified by JO from Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

3. WHAT DO YOU THINK EARLY EARTH WAS LIKE?
HOW OLD? 4.5 BILLION YEARS?
BIG BANG - GRAVITY CAUSES DUST PARTICLES TO CONDENSE
METEORS FOR MILLIONS OF YEARS - HOW HOT WOULD THE EARTH BE? Cold or hot?
EARTH HAS TO COOL DOWN - STEAM ESCAPES AND RAIN ALLOWS COLLECTION OF WATER - EARTH NOW HAS……
ATMOSPHERE OF AMMONIA, METHANE, WATER VAPOR, CO2, AND NITROGEN
WHAT IS MISSING?
OXYGEN IS MISSING!
Modified by JO from Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

4. THE HISTORY OF LIFE EARLY HISTORY OF EARTH EVIDENCE
HOW OLD IS SOMETHING?
WHAT IS GEOLOGIC TIME?
FIRST CELLS
ENDOSYMBIONT THEORY
Courtesy NASA/JPL-Caltech
Modified by JO from Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

5. WHAT EVIDENCE DO SCIENTISTS USE?
FOSSILS!
TRACE
MOLD
CAST
AMBER
IMPRINT
PETRIFIED
Images courtesy of the UC Museum of Paleontology Understanding Evolution:
Modified by JO from Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

6. WHERE ARE FOSSILS USUALLY FOUND? WHO STUDIES THESE? PALAENTOLOGISTS!
HOW DO SCIENTISTS DETERMINE THE AGE OF SOMETHING BILLIONS OF YEARS OLD?
RELATIVE DATING
RADIOMETRIC DATING
Understanding Evolution:
Modified by JO from Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

7. THE HISTORY OF LIFE EARLY HISTORY OF EARTH EVIDENCE
HOW OLD IS SOMETHING?
WHAT IS GEOLOGIC TIME?
FIRST CELLS
ENDOSYMBIONT THEORY
Courtesy NASA/JPL-Caltech
Modified by JO from Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

8. PRECAMBRIAN PALEOZOIC MESOZOIC CENOZOIC GEOLOGICAL TIME
TOO OLD FOR YEARS OR MONTHS
FOUR ERAS DEPENDING ON WHICH ORGANISMS LIVED:
PRECAMBRIAN
PALEOZOIC
MESOZOIC
CENOZOIC
Modified by JO from Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

9. WHY DO WE HAVE DIFFERENT ERA’S?
Image courtesy of the UC Museum of Paleontology Understanding Evolution:
Modified by JO from Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

10. PRECAMBRIAN ERA WHAT DO SCIENTISTS THINK WAS ALIVE WAY BACK THEN?
BACTERIA
THIS ERA LASTED FOR BILLIONS OF YEARS UNTIL MORE LIVING ORGANISMS EVOLVED
Dr Gordon Beakes © University of Newcastle upon Tynelicensed
Dr Tom Tregenza © Tom Tregenza
Modified by JO from Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

11. PALEOZOIC ERA 540 MILLION YEARS AGO!!
NOW THE EARTH SUPPORTS LARGER ORGANISMS
FIRST PART OF PALEOZOIC IS CALLED CAMBRIAN
PROTISTS!
SEA PLANTS!
SEA ANIMALS!
LAND PLANTS!
LAND ANIMALS!
WHAT ENDED THE PALEOZOIC ERA??
MASS EXTINCTION!
Dr. Thomas W. Kammer
Modified by JO from Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

12.
Images courtesy of the UC Museum of Paleontology Understanding Evolution:
Images courtesy of the UC Museum of Paleontology Understanding Evolution:
Modified by JO from Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

13. MESOZOIC ERA 245 MILLION YEARS AGO!!
Some serious evolution has occurred!
DINOSAURS
REPTILES
SMALL MAMMALS APPEAR
BIRDS EVOLVE
PLATE TECTONICS
WHAT ENDED THE MESOZOIC ERA?
MASS EXTINCTION!
? METEORITE
Modified by JO from Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

14. Images courtesy of the UC Museum of Paleontology Understanding Evolution:
Modified by JO from Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

15. CENOZOIC ERA 66 MILLION YEARS AGO!
MAMMALS FLOURISH
PRIMATES ABOUT 30 MILLION YEARS AGO
MODERN HUMAN SPECIES – ABOUT 200,000 YEARS AGO
Modified by JO from Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

16. Tom Tregenza © Tom Tregenza
Dr Gordon Beakes © University of Newcastle upon Tyne
Prof Paul F. Brain © University of Wales, Swansea
licensed for use through the Centre for Bioscience ImageBank,
Modified by JO from Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

17. THE HISTORY OF LIFE EARLY HISTORY OF EARTH EVIDENCE
HOW OLD IS SOMETHING?
WHAT IS GEOLOGIC TIME?
FIRST CELLS
ENDOSYMBIONT THEORY
Courtesy NASA/JPL-Caltech
Modified by JO from Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

18. WHERE DID THE FIRST CELLS COME FROM?
DOES ANYONE KNOW FOR SURE?
SPONTANEOUS GENERATION v BIOGENESIS
FRANCESCO REDI – maggots come from the eggs of flies
LOUIS PASTEUR – rejects spontaneous generation
Modified by JO from Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

19. LOUIS PASTEUR’S EXPERIMENTS
Pasteur filled a flask with medium, heated it to kill all life, and then drew out the neck of the flask into a long S.
This prevented microorganisms in the air from entering the flask, yet allowed air to flow freely.
If the swan neck was broken, microbes could enter the flask and grow.
With these results, Pasteur rejects spontaneous generation.
Modified by JO from Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

20. COULD THE FIRST ORGANIC MOLECULES HAVE FORMED SPONTANEOUSLY?
ALEXANDER OPARIN – ‘Primordial soup’
STANLEY MILLER AND HAROLD UREY – simulated the Earth’s early atmosphere and showed that organic molecules could be spontaneously created from the chemicals present then
Modified by JO from Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

21. SINGLE CELLED ORGANISMS NOW!
FIRST BACTERIA AROUND 3.5 BILLION YEARS AGO
SOME ARE CYANOBACTERIA - THESE ARE PHOTOSYNTHETIC BACTERIA – Hmmmmm!!!
WHAT ARE THESE BACTERIA GOING TO PRODUCE? OXYGEN!
WHAT TYPE OF CELLS ARE BACTERIA? PROKARYOTES!
WHAT TYPE OF CELLS ARE ALL OTHER ORGANISMS? EUKARYOTES!
WHERE DID EUKARYOTIC CELLS COME FROM?
ENDOSYMBIOSIS!
ENDOSYMBIOSIS?
Modified by JO from Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

22. THE HISTORY OF LIFE EARLY HISTORY OF EARTH EVIDENCE
HOW OLD IS SOMETHING?
WHAT IS GEOLOGIC TIME?
FIRST CELLS
ENDOSYMBIONT THEORY
Courtesy NASA/JPL-Caltech
Modified by JO from Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

23. ENDOSYMBIOSIS BEGINNING OF THE EUKARYOTIC CELLS
EVIDENCE FOR ENDOSYMBIOSIS?
Organelle size is approximately bacteria size
Membrane-bound organelles
Mitochondria and chloroplasts have their own DNA and ribosomes
Modified by JO from Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.