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The History of Earth & Life
Spontaneous Generation
The idea that living things could arise
from nonliving things. T
Believers included great minds like:
Aristotle
Sir Isaac Newton
(384 BC - 322 BC)
1643 - 1727
Spontaneous Generation
• raw meat gave birth to maggots
• rotting logs at the bottom of lakes & rivers
gave birth to alligators and crocodiles
Spontaneous Generation
• mice from dirty hay
• Mud gives birth to mudpuppies
• Morning dew giving rise to ladybugs
Disproving Spontaneous Generation
• Francesco Redi (1626-1697) - a scientist who
used experiments to disprove spontaneous
generation of macro (large) organisms.
» Results: Covered flask
Open flask
no maggots
maggots
Conclusion: Raw meat does not give rise to maggots.
THE MAGGOTS CAME FROM FLIES!!!
Disproving Spontaneous Generation
• With the discovery of the
microscope, scientists found a tiny
world teeming with life.
• Scientists concluded that
microorganisms arise spontaneously
from a “Vital Force” in the air.
• In definition “Vital Force” states
that microorganisms arise
spontaneously from the air.
Disproving Spontaneous Generation
of Microorganisms
• Lazzaro Spallanzani (1729-1799) attempted to disprove
spontaneous generation
of microorganism.
• He stated that microorganisms
formed from other microorganisms, not from air.
• Many skeptics still believed in the “Vital
Force” & spontaneous generation hung
around for another 100 years.
Disproving Spontaneous
Generation
of Microorganisms
• By the mid 1800s, the controversy of
spontaneous generation had grown
fierce.
• The Paris Academy of Science offered
a prize to anyone who could clear up
the issue of spontaneous generation.
Disproving Spontaneous Generation
of Microorganisms
• Louis Pasteur (1822 - 1895) used a curvenecked flask.
• This technique allowed air with the so
called “Vital Force” to mix with the broth
in the flask, but prevented
microorganisms from entering the body
of the flask.
History of Earth
The solar system formed 5 billion years ago.
History of Earth
• Earth & other planets formed about 4.6
billion years ago by repeated collisions from
space debris.
• 2000˚ F - same as the Sun
• The surface is a entirely molten
• Thea (Mars -sized planet)
collides with Earth at
25,000 mph.
• Sent billions of tons of
debris from Earth’s crusts.
• Over 100 years a ring of
hot dust & rock circled the
Earth, collecting more
debris forming the Moon.
• 1/50th the size of Earth.
Great Impact
Theory -1974
Spin Off Theory
• The Earth was very
hot and spinning
rapidly.
• Moon split off of it.
History of Earth - 3.5 billion years ago
• Early volcanic activity formed earth’s
atmosphere.
• Millions & millions of years of rain filled
the oceans, lakes & rivers.
• Iron rich oceans - green in color.
• Temperature exceeds 200˚ F.
History of Earth
• Early earth’s atmosphere was very
inhospitable.
1.
2.
3.
4.
5.
6.
Very little O2 – (oxygen)
Mostly water vapor
Nitrogen
Methane(carbon based compound) CH4
Ammonia (inhospitable) NH3
Hydrogen (H2)
History of Earth 2.5 to 1.5 billion years ago
• Granite continents rise from the mantle.
• Stromatolites - are cyanobacteria found
around every continent that produced O2
Stromatolites - aka cyanobacteria
• The O2 rusted out the iron filled oceans
turning all green oceans blue.
• All this O2 formed the ozone (O3) layer
protecting the Earth from harmful UV rays,
allowing multi-cellular organisms.
History of Earth - 700 million years ago
• Snowball Earth - 40˚F
• All life gone, except marine bacteria &
algae in the oceans under the ice.
• The core & volcanic
eruptions caused a
greenhouse effect &
the Earth heated up.
History of Earth -225 million years ago
Pangaea(one
land mass) to present day earth.
ALFRED WEGENER 1912
The Theory of PLATE TECTONICS
or
The Theory of CONTINENTAL DRIFT
Wegener noticed similarities in
organisms from different
continents
“All in the family”
• Ostrich –
• Africa
*******************
• Emu –
• Australia
**************
• Rhea –
• South America
Wegener noticed other similarities
• Fossils indicate that the camel
family originated in North America
– where it became extinct.
• Migrated to South America Llamas,
alpacas, vicunas
• Also migrated to Asia via Siberia.
Africa and central Asia.
In addition, Wegener noted:
• Fossil records show tropical plants in the artic
Found Trilobites all over the world.
• Particularly common
fossil.
• Found primarily in
rocks from the first
half of the Paleozoic
era.
History of Earth - after Pangaea
• as Pangaea broke apart the Earth was battered
by many asteroids, volcanic eruptions & ice ages.
• 66 million years ago a huge asteroid (as big as
Mt. Everest) collided with the Earth, sending
debris & dust that totally blocked out the Sun.
• the Earth began another ice age
• all plant life died, followed by the Dinosaurs &
almost all other organisms died.
• last ice age occurred 12,000 years ago.
Earth - Present day
Earth
How old is the Earth?
• During the mid 1600's,
Archbishop James Usher of
Ireland, calculated the age of the
earth based on the genealogies
from Adam and Eve.
• According to Usher's calculations,
the earth was formed on October
22, 4004 B.C. Making the Earth
almost 6,000 years old.
How old is the Earth?
• Many geological structures and
processes cannot be explained if
the earth is only 6000 years old.
• The Grand Canyon was actually
formed in 6 million years .
• Nearly two billion years of the
Earth's geological history have been
exposed as the Colorado River and its
tributaries cut their channels
through layer after layer of rock
while the Colorado Plateau was
uplifted.
• The Grand Canyon’s Sky Walk
How old is the Earth?
• Leonardo da Vinci - painter,
architect and engineer.
• Calculated the sedimentation rates
in the Po River of Italy.
• Concluded it took 200,000 years to
form some nearby rock deposits.
How old is the Earth?
• Relative Dating - uses rock layers to
date fossils.
The lower the
object is the older it is.
Examples: Grand canyon,
Stack of newspapers
Relative Dating:
The process of putting things in a "correct order”
Use #”s 1-7
2 I got out bread, peanut butter and jelly.
• ___
6 I ate the sandwich.
• ___
5 I put the two pieces of bread together.
• ___
4 I spread a layer of jelly on another piece of bread.
• ___
1 I was hungry.
• ___
3 I spread a layer of peanut butter on a piece bread.
• ___
Relative Dating:
•
Radiometric dating
• Determines the age of an object by the
natural decay of an element.
• Radioactive isotope C14 decays to C12
• Isotopes- are the same element, same #
of protons, but different # of neutrons.
How old is the Earth?
• C14 is used to date living or once living things
• When organisms dies
it contains 100% C14
• In one half-life the
organism will have
50% C14 & 50% C12
• C14 has a half life of
5730 years
C14 - red
C12 - blue
• Carbon 14 half-life
is 5730 years.
• In one half-life how
50
much C14 - ______%.
How old is the
5730
organism? _____
• In two half-lives how
much C14 - ______%.
25
How old is the
11460
organism? ______
How old is the Earth?
• C14 dates objects up to
50,000 years old
• Isotope potassium 40 has a halflife of 1.3 billion & therefore
used to date the earth
• potassium 40 decays into argon 40
How old is the Earth?
Life on Earth?
• In the 1920s, Alexander Oparin
and J. B. S. Haldane proposed an
idea for how life may have
originated on Earth.
• They stated early atmosphere contained very
little O2 ammonia(NH3)
H2 gas
water vapor & methane(CH4)
Life on Earth?
• Oparin & Haldane stated that, as
the earth cooled these gases
condensed & collected in a
“primordial soup”.
• These elements, triggered by
lightning combined to form
proteins, the building blocks for
life.
Life on Earth?
• Stanley Miller & Harold
Urey set up
Oparin’s hypothesis.
• The experiment was
successful as it
produced organic
molecules from
inorganic substances.
Life on Earth?
• From 4.6 to 3.6 billion years ago
the earth was very inhospitable.
• By 3.9 billion, the earth cooled
and water vapor condensed in the
atmosphere, filling the oceans for
millions & millions of years.
Life on Earth?
• Primordial soup - pools
of water that contain
the essential ingredients
for life.
Life on Earth?
• Simple organic (carbon) molecules changed
into proteins, carbs & nucleic acids.
• Protocells are formed from the complex
organic molecules. Protocells are the first
cells(a living thing enclosed by a membrane).
• Protocells formed between
3.9-3.5 billions of years ago.
Examples of Protocells;
microsphere & coacervates
Life on Earth?
•
Prokaryotes cells that lack organelles.
evolved from protocells.
no O2 in atmosphere, therefore anaerobic
heterotrophs - consumed organic molecules
•
Autotrophs (make their own food)
evolved after prokaryotes make glucose
by chemosynthesis, not photosynthesis
•
Photosynthetic prokaryotes evolved due to an
increase in atmospheric O2 levels.
Life on Earth?
• Eukaryotes - cells that
contain organelles.
as O2 levels rose lightning converted
much of the O2 into ozone.
this ozone layer protected more
advance organisms, such as eukaryotes.
asmmm2
Life on Earth?
• Endosymbiotic Theory - explains how
eukaryotic plant & animal cells evolved.
asmmm2
Geological Time Scale
Multi-cellular
organism
Put the following in order from primitive to more
advance:
• Cenozoic (2)
• Precambrian (5)
1. Precambrian
_________ era
• Paleozoic (3)
a. Protocells
• Mesozoic (1)
b. Prokaryotes heterotrophs
• explosion of Life
c. Prokaryotes autotrophs
• reptile & dinos
d. Eukaryotes
• multi-cellular organisms
e. Multi-cellular organism
Paleozoic era
• mammals
2. _________
• prokaryotes (autotrophs)
a. Fish
• prokaryotes (heterotrophs)
b. Amphibians
• fish
c. Pangaea - broke up
225 million years ago
Explosion
• amphibians
• homo sapiens
3. Mesozoic
_________ era
eukaryotes
a.
of life
Reptiles & Dinos
• Protocells
Cenozoic
• Pangaea - broke up 225
4. _________era
million years ago
a. Homo sapiens b. mammals
Charles Darwin
(1809-1882)
• Between 1831 and 1836
Charles Darwin traveled
around the world on The Beagle.
• He was hired to chart the eastern
coastline of South America.
• He was only 21 years old.
Charles Darwin’s Voyage of Discovery
Darwin’s book
“On the Origin of Species”
published in 1859 is
considered a
milestone event.
Charles Darwin’s
The Theory of Evolution
Darwin’s Theory of Evolution -
the process by which different kinds
of organisms are thought to have
changed or developed over a long
period of time.
Darwin (continue)
• Darwin spent much time ashore
collecting plant, animal and fossil
specimens, as well as making extensive
geological observations.
• On his return to England in 1836,
Darwin began to catalog his collections
and ponder the seeming "fit" of
organisms to their mode of existence.
• He eventually settled on
four main points of the theory.
Darwin (continue)
Adaptation: all organisms adapt to their
environments.
Variation: all organisms are variable in
their traits.
Over reproduction: all organisms tend to
reproduce beyond their environment's
capacity to support them
Natural selection: Since not all
organisms are equally well adapted to
their environment, some will survive and
reproduce better than others.
Sometimes this is also referred to as
"survival of the fittest”.
Darwin (continue)
• Not all members of a population
necessarily have an equal chance of
surviving and reproducing (due to
competition for resources and mates).
• The better adapted individuals are more
"fit" and tend to survive and reproduce,
passing on their adaptations to the next
generation in greater frequency than
those adaptations of the less "fit"
members of the population.
• Natural selection:
is the process of survival and
reproduction that inevitably leads
to changes in allele frequencies over
time as those individuals who are
the most "fit" survive and leave
more offspring.
Natural Selection - three types
• Stabilizing selection:
favors the average phenotype
out of a range of phenotypes.
• Disruptive selection:
favors individuals at both
extremes of variation:
selection is against the
middle of the curve.
• Directional selection
favors phenotypes of one extreme
of the range of variation.
Another thought on Evolution called
Inheritance of acquired traits
Jean Baptiste Lamarck
believed that organisms “acquire traits”
during their life time & are able to pass
their newly acquire traits to their
offspring
This was not true!
Examples: sun tan
appendicitis
Evidence of Evolution
• A fossil is a trace of a previously existing
organism. They come in many forms.
• Most fossils occur in sedimentary rock.
• The fossil record is not complete .
Skeletal Remains
Footprints embedded in Rock
Insects trapped in tree sap
Galileo
• studied fossils (evidence of past life)
and concluded that they were real
and not inanimate artifacts
Galileo finger
• convicted heretic
for his contention
that the earth was
not the center of
the Universe
Evidence of Evolution
The structures of many similarly related organisms have
many similarities. For example, the forelimbs of
mammals contain the same number of bones in the
the
human forearm.
Evidence of Evolution
• Homologous structures are structures that share a
common ancestry. The forelimbs of all vertebrate are
constructed from the same array of bones.
• Analogous structures are structures that have a similar
function but do not share a common ancestry.
Evidence of Evolution
• Vestigial structures are considered to be evidence of an
organism’s evolutionary past. They are bones or other
structures that are reduced in size and appear to have no
use or a less important use than in other organisms.
• Examples: Human tailbone & appendix.
Ostrich & penguin wings. Whale hip.
Evidence of Evolution
• Isn’t it interesting that every living
organism, from the eagle flying above,
to the sea sponges on the ocean floor
share the same chemical makeup?
• Every organism is composed of
the same nitrogen bases(ATGC)
that make up DNA.
• The greater the similarity in
the DNA sequence, the more
closely related they are.
Red Panda
Evidence of Evolution
• Embryology is the study of
the embryo(early stage of
development).
Many organisms share
similarities in the embryo
stage.
• The human embryo
develops and then loses
artifacts like
gill pouches and tails.
FISH
BIRD PIG HUMAN
FIS
H
Convergent Evolution
Convergent evolution
unrelated species have similar
adaptations to similar environments.
Divergent Evolution or
adaptive evolution
Divergent evolution
The evolution from a common ancestor to a
variety of species.
Example: Hawaiian honeycreepers
Divergent Evolution or
adaptive evolution
Darwin’s finches - presently there are 13
species of finches. Darwin suggest that
they came from common ancestors.
The rapid evolution of a single species to fill
many ecological niches from one ancestor.
•
Mimicry is the resemblance of one
organism (mimic) to another
North American King Snake
"Red to yellow, Kill a fellow; Red to black, Venom lack”
• Extinction is the process in which
groups of organisms (species) die out.
Over 99 per cent of the species that have
ever lived have gone extinct.