THE HISTORY OF LIFE• EARLY HISTORY

OF EARTH• EVIDENCE• HOW OLD IS

SOMETHING?• WHAT IS

GEOLOGIC TIME?• FIRST CELLS• ENDOSYMBIONT

THEORY

Courtesy NASA/JPL-Caltechhttp://origins.jpl.nasa.gov/habitable-planets/invest16.html

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

•EARTH HAS TO COOL DOWN - STEAM ESCAPES AND RAIN ALLOWS COLLECTION OF WATER

WHAT DO YOU THINK EARLY EARTH WAS LIKE?

•EARTH NOW HAS……ATMOSPHERE OF AMMONIA, METHANE, WATER VAPOR, CO2, AND NITROGEN

THE HISTORY OF LIFE

•EVIDENCE

WHAT EVIDENCE DO SCIENTISTS USE?

• FOSSILS!

–TRACE

–MOLD

–CAST

–AMBER

WHERE ARE FOSSILS USUALLY FOUND?

•WHO STUDIES THESE?

•HOW DO SCIENTISTS DETERMINE THE AGE OF SOMETHING BILLIONS OF YEARS OLD?

RELATIVE DATING

RADIOMETRIC DATING

WHERE ARE FOSSILS USUALLY FOUND?

Relative Dating

THE HISTORY OF LIFE

• WHAT IS GEOLOGIC TIME?

• FIRST CELLS• ENDOSYMBIONT

THEORY

GEOLOGICAL TIME

• TOO OLD FOR YEARS OR MONTHS

• FOUR ERAS DEPENDING ON WHICH ORGANISMS LIVED

• PRECAMBRIAN

• PALEOZOIC

• MESOZOIC

• CENOZOIC

GEOLOGICAL TIME

WHY DO WE HAVE DIFFERENT ERA’S?

Image courtesy of the UC Museum of Paleontology Understanding Evolution: http://evolution.berkeley.edu."

PRECAMBRIAN• WHAT DO SCIENTISTS THINK WAS

ALIVE WAY BACK THEN??

• BACTERIA

• THIS ERA LASTED FOR BILLIONS OF YEARS UNTIL MORE LIVING ORGANISMS EVOLVED

PALEOZOIC ERA540 MILLION YEARS AGO!!

• NOW THE EARTH IS GETTING LARGER LIFE!

• FIRST PART OF PALEOZOIC IS CALLED CAMBRIAN

• PROTISTS!

• SEA PLANTS!Dr. Thomas W. Kammer

PALEOZOIC ERA540 MILLION YEARS AGO!!

• SEA ANIMALS!

• LAND PLANTS!

• LAND ANIMALS!

• WHAT ENDED THE PALEOZOIC ERA??

• MASS EXTINCTION!

MESOZOIC ERA245 MILLION YEARS AGO!!

• DINOSAURS

• REPTILES

• SMALL MAMMALS APPEAR

• BIRDS EVOLVE

MESOZOIC ERA245 MILLION YEARS AGO!!

• PLATE TECTONICS• WHAT ENDED THE

MESOZOIC ERA?• MASS EXTINCTION!• ? METERORITE

CENOZOIC ERA66 MILLION YEARS AGO!

• MAMMALS FLOURISH

• PRIMATES ABOUT 30 MILLION YEARS AGO

• MODERN HUMAN SPECIES – ABOUT 200,000 YEARS AGO

THE HISTORY OF LIFE

• FIRST CELLS• ENDOSYMBIONT

THEORY

Courtesy NASA/JPL-Caltechhttp://origins.jpl.nasa.gov/habitable-planets/invest16.html

HOW WERE THE FIRST CELLS MADE?

• DOES ANYONE KNOW FOR SURE?

• SPONATEOUS GENERATION VS BIOGENESIS

• FRANCESCO REDI

• LOUIS PASTEUR’S

• EXPERIMENThttp: //en.w ikipedia.org/wiki/Louis_Pasteur

LOUIS PASTEUR

LPPasteur filled a flask with medium, heated it to kill all life,and then drew out the neck of the flask into a long S.

LP• This prevented

microorganisms in the air from entering the flask

• Allowed air to flow freely. If the swan neck was broken, microbes could enter the flask and grow.

• ALEXANDER OPARIN - CREATION OF MACROMOLECULES WITHOUT OXYGEN

• STANLEY MILLER AND HAROLD UREY EXPERIMENT

• FIRST BACTERIA AROUND 3.5 BILLION YEARS AGO

ONE CELL ORGANISMS NOW!

SOME ARE CYANOBACTERIA - THESE ARE PHOTOSYNTHETIC BACTERIA - HMMMMMMMWHAT ARE THESE BACTERIA GOING TO PRODUCE?

ONE CELL ORGANISMS NOW!

•ALMOST 10% ABOUT 2.5 BILLION YEARS AGO•WHAT TYPE OF CELLS ARE BACTERIA?

WHAT TYPE OF CELLS ARE ALL OTHER ORGANISMS?WHERE DID EUKARYOTIC CELLS COME FROM?ENDOSYMBIOSIS

THE HISTORY OF LIFE

• ENDOSYMBIONT THEORY

• Proposed by Lynn Margulis in 1960

Courtesy NASA/JPL-Caltechhttp://origins.jpl.nasa.gov/habitable-planets/invest16.html

ENDOSYMBIOSIS BEGINNING OF THE EUKARYOTIC CELLS

• EVIDENCE FOR ENDOSYMBIOSIS

• DNA