Download History of Life On Earth

THE HISTORY OF LIFE
• EARLY GEOLOGIC HISTORY
OF EARTH
• GEOLOGIC EVIDENCE
• DATING OF ROCKS AND
FOSSILS
• GEOLOGIC TIME
• THE FIRST CELLS
• FOSSIL EVIDENCE
• ENDOSYMBIONT
HYPOTHESIS
Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
THE HISTORY OF LIFE
• EARLY GEOLOGIC HISTORY
OF EARTH
• GEOLOGIC EVIDENCE
• DATING OF ROCKS AND
FOSSILS
• GEOLOGIC TIME
• THE FIRST CELLS
• FOSSIL EVIDENCE
• ENDOSYMBIONT
HYPOTHESIS
Courtesy NASA/JPL-Caltech
http://origins.jpl.nasa.gov/habitable-planets/invest16.html
Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
Origin of Earth
• EARTH IS AT LEAST 4.5 BILLION
YEARS
• EVIDENCE: oldest known rocks
Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
• About 15 billion years ago an explosion started the
expansion of the universe.
• Known as the Big Bang.
• At the point of this event all of the matter and energy of
space was contained at one point.
• What existed prior to this event is completely unknown
and is a matter of pure speculation. This occurence was not
a conventional explosion but rather an event filling all of
space with all of the particles of the embryonic universe
rushing away from each other.
• Consisted of an explosion of space within itself
• Galaxies were not all clumped together, but rather the Big
Bang lay the foundations for the universe.
• Credited to Edwin Hubble. Hubble made the observation
that the universe is continuously expanding. He discovered
that a galaxys’ velocity is proportional to its distance.
Galaxies that are twice as far from us move twice as fast.
Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
Conditions of Early Earth
• METEORS IMPACT EARTH FOR MILLIONS OF
YEARS, DEPOSIT LARGE QUANTITIES OF WATER
IN THE FORM OF ICE
• EARTH COOLS DOWN - STEAM ESCAPES AND
RAIN FORMS
• WATER COLLECTS IN LOW AREAS
• ATMOSPHERE FORMS; AMMONIA,
METHANE, WATER VAPOR, CO2, AND
NITROGEN GASSES
• WHAT GAS IS MISSING? Hint: →
• CONDITIONS NOT SUITABLE FOR LIFE YET
Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
THE HISTORY OF LIFE
• EARLY GEOLOGIC HISTORY
OF EARTH
• GEOLOGIC AND FOSSIL
EVIDENCE
• DATING OF ROCKS AND
FOSSILS
• GEOLOGIC TIME
• THE FIRST CELLS
• FOSSIL EVIDENCE
• ENDOSYMBIONT
HYPOTHESIS
Courtesy NASA/JPL-Caltech
http://origins.jpl.nasa.gov/habitable-planets/invest16.html
Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
Evidence for Past Life
• FOSSILSremains and
traces of past
life. Types:
–
–
–
–
–
–
TRACE
MOLD
CAST
AMBER
IMPRINT
PETRIFIED
Images courtesy of the UC Museum of Paleontology Understanding Evolution: http://evolution.berkeley.edu."
Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
• WHERE ARE FOSSILS USUALLY FOUND? In sedimentary rock
layers
• WHO STUDIES THESE? paleontologists
• HOW DO SCIENTISTS DETERMINE THE AGE OF SOMETHING
BILLIONS OF YEARS OLD? By “dating” igneous rocks near fossils
– RELATIVE DATING; age relative to some known date
– RADIOMETRIC DATING; an absolute date determined by rate of
radioactive decay of isotopes
Understanding Evolution: http://evolution.berkeley.edu."
Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
THE HISTORY OF LIFE
• EARLY GEOLOGIC
HISTORY OF EARTH
• GEOLOGIC AND FOSSIL
EVIDENCE
• DATING OF ROCKS AND
FOSSILS
• GEOLOGIC TIME
• THE FIRST CELLS
• FOSSIL EVIDENCE
• ENDOSYMBIONT
HYPOTHESIS
Courtesy NASA/JPL-Caltech
http://origins.jpl.nasa.gov/habitable-planets/invest16.html
Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
GEOLOGICAL TIME
• TIME TOO OLD FOR
YEARS OR MONTHS
• DIVIDED INTO FOUR
ERAS BASED ON
DOMINANT LIFE
FORMS
1.
2.
3.
4.
PRECAMBRIAN (oldest)
PALEOZOIC
MESOZOIC
CENOZOIC (youngest)
Or Precambrian
Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
WHY DO WE HAVE DIFFERENT ERAS?
To Mark Major Mass Extinctions
Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
PRECAMBRIAN
• WHAT LIVED IN THE Precambrian ERA?
Bacteria & Algae
Stromatolitesformed from
algae/bacteria
Cyanobacteria IMAGES for use through the Centre for Bioscience that secrete a
ImageBank,http://www.bioscience.heacademy.ac.uk/ima
sticky slime that
Life Sciences-HHMI Outreach. Copyrightgebank/"
2006 President
traps minerals
and Fellows of Harvard College.
WHAT LIVED IN THE PALEOZOIC
ERA?
• MULTICELLULAR LIFE FORMS:
–
–
–
–
–
–
Marine Invertebrates
Fish
Amphibians
Insects
Reptiles
Land Plants-ferns and evergreens
Crenoids
• WHAT ENDED THE PALEOZOIC ERA? A “Mass
Extinction”-massive die off of species due to sudden
environmental change
IMAGES for use through the Centre for Bioscience ImageBank,http://www.bioscience.heacademy.ac.uk/imagebank/"
Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
www.carnegiemnh.org/ip/tours/virtual/hall.htm
Image courtesy of the UC Museum of Paleontology Understanding Evolution: http://evolution.berkeley.edu."
Image courtesy of the UC Museum of Paleontology Understanding Evolution: http://evolution.berkeley.edu."
Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
WHAT LIVED IN THE MESOZOIC
ERA?
– Birds
– Flowering Plants
– Dinosaurs
Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
Archaeoptryx
Allosaurus
Liaoconodon hui
Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
Plesiosour
WHAT LIVED IN THE CENOZOIC ERA?
– MAMMALS
– PRIMATES ABOUT 30 MILLION YEARS AGO
– MODERN HUMAN SPECIES – ABOUT 200,000
YEARS AGO
Morganucodon
(early mammal)
Smilodon
(later mammal)
Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
THE HISTORY OF LIFE
• EARLY GEOLOGIC HISTORY
OF EARTH
• GEOLOGIC AND FOSSIL
EVIDENCE
• DATING OF ROCKS AND
FOSSILS
• GEOLOGIC TIME
• THE FIRST CELLS
• FOSSIL EVIDENCE
• ENDOSYMBIONT
HYPOTHESIS
Courtesy NASA/JPL-Caltech
http://origins.jpl.nasa.gov/habitable-planets/invest16.html
Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
How Did Life Begin?
• DOES ANYONE KNOW FOR SURE? No
• SPONATEOUS GENERATION-the idea that life could come
from non-living things (based on the observation that mice
appeared from a pile of rags and wheat)
• 1668-FRANSISCO REDI PROVED THAT LIFE COULD
ONLY COME FROM LIVING THINGS, SPECIFICALLY,
THAT FLIES COULD ONLY COME FROM OTHER FLIES.
Redi’s controlled
experiment concluded that
small living things come
from small living things
Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
IDEAS ON THE FORMATION OF THE BASIC
CHEMICALS OF LIFE
•
•
PRIMORDIAL SOUP MODEL– HYPOTHESIS THAT OCEANS FILLED
WITH ORGANIC MOLECULES, NO OXYGEN, THUS UNDER THE
RIGHT CONDITIONS, ELECTRONS FREE TO REACT WITH
HYDROGEN RICH MOLECULES TO FORM ORGANIC COMPOUNDS
STANLEY MILLER AND HAROLD UREY EXPERIMENT-TESTED THE
PRIMORDIAL SOUP MODEL AND DID PRODUCE ORGANIC
COMPOUNDS
Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
• BUBBLE MODEL-KEY CHEMICAL
PROCESSES TOOK PLACE WITHIN BUBBLES
ON OCEAN’S SURFACE
Microspheres and Coacervates -lipid droplets that
contain amino acids, can make in a simulated early
earth experiment
Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
THE HISTORY OF LIFE
• EARLY GEOLOGIC HISTORY
OF EARTH
• GEOLOGIC AND FOSSIL
EVIDENCE
• DATING OF ROCKS AND
FOSSILS
• GEOLOGIC TIME
• THE FIRST CELLS
• FOSSIL EVIDENCE
• ENDOSYMBIONT
HYPOTHESIS
Courtesy NASA/JPL-Caltech
http://origins.jpl.nasa.gov/habitable-planets/invest16.html
Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
FOSSIL EVIDENCE FOR OLDEST
CELLS
Living Stromatolites- chalky
mounds built up of layers of
microbial secretions and
trapped sediments.
Fossil Stromatolites-discovered
in Western Australia have been
dated to 3.5 billion years ago
Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
ONE CELL ORGANISMS (Unicellular)
• FIRST BACTERIA AROUND 3.5 BILLION YEARS AGO
• SOME ARE CYANOBACTERIA - THESE ARE
PHOTOSYNTHETIC BACTERIA
• WHAT DO THESE BACTERIA PRODUCE? Oxygen
• WHAT DOES OZONE, O3, DO? Screens out UV radiation
• WHAT TYPE OF CELLS ARE BACTERIA? Prokaryotes
• WHAT TYPE OF CELLS ARE ALL OTHER ORGANISMS?
Eukaryotes
• WHERE DID EUKARYOTIC CELLS COME FROM?
• Hypothesis: ENDOSYMBIOSIS
Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
THE HISTORY OF LIFE
• EARLY GEOLOGIC HISTORY
OF EARTH
• GEOLOGIC AND FOSSIL
EVIDENCE
• DATING OF ROCKS AND
FOSSILS
• GEOLOGIC TIME
• THE FIRST CELLS
• FOSSIL EVIDENCE
• ENDOSYMBIONT
HYPOTHESIS
Courtesy NASA/JPL-Caltech
http://origins.jpl.nasa.gov/habitable-planets/invest16.html
Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
ENDOSYMBIOSIS
BEGINNING OF THE EUKARYOTIC CELLS
• EVIDENCE FOR ENDOSYMBIOSIS
– Chloroplasts and mitochondria have their own DNA
– Are about the same size and structure as bacteria (prokaryotes)
– Have similar ribosomes as bacteria
Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.