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 no maggots Open flask

maggotsConclusion: 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 microorganismsformed from other micro-

organisms, 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

curve-necked 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 EarthThe 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

Great Impact Theory -1974

• 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.

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. Very little O2 – (oxygen)

2. Mostly water vapor3. Nitrogen4. Methane(carbon based compound)

CH4

5. Ammonia (inhospitable) NH3

6. 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

• Ostrich –• Africa*******************

• Emu –• Australia************** • Rhea – • South America

“All in the family”

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 • ___ I got out bread, peanut butter and jelly.

• ___ I ate the sandwich.

• ___ I put the two pieces of bread together.

• ___ I spread a layer of jelly on another piece of bread.

• ___ I was hungry.

• ___ I spread a layer of peanut butter on a piece bread.

1

2

3

4

5

6

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 diesit contains 100% C14

• In one half-life the organism will have50% C14 & 50% C12

• C14 has a half life of5730 years

C14 - red C12 - blue

• Carbon 14 half-life is 5730 years.

• In one half-life howmuch C14 - ______%.

How old is theorganism? _____

• In two half-lives how much C14 - ______%. How old is the organism? ______

50

5730

25

11460

How old is the Earth?

•C14 dates objects up to 50,000 years old

•Isotope potassium 40 has a half-life 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 anaerobicheterotrophs - 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 ScalePut the following in order from primitive to more advance:• Cenozoic (2)• Precambrian (5) 1. _________ era• Paleozoic (3) a.• Mesozoic (1) b.• explosion of Life c.• reptile & dinos d.• multi-cellular organisms e.• mammals 2. _________ era• prokaryotes (autotrophs) a. • prokaryotes (heterotrophs) b. • fish c.• amphibians• homo sapiens 3. _________ era eukaryotes a. • Protocells• Pangaea - broke up 225 4. _________era

million years ago a. b.

Precambrian Protocells

Prokaryotes autotrophs

Eukaryotes

Multi-cellular organism

PaleozoicFishAmphibiansPangaea - broke up 225 million years ago

Mesozoic

Reptiles & Dinos

CenozoicHomo sapiens

Explosion

of life

Prokaryotes heterotrophs

Multi-cellular organism

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 DiscoveryCharles Darwin’s Voyage of Discovery

Darwin’s book Darwin’s book ““On the Origin of Species” On the Origin of Species” published in 1859 is published in 1859 is considered a considered a milestone event.milestone event.

Charles Darwin’s Charles Darwin’s The Theory of EvolutionThe Theory of Evolution

Darwin’s 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 .

Insects trapped in tree sapFootprints embedded in RockSkeletal Remains

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

FISH BIRD PIG HUMAN

Convergent EvolutionConvergent Evolution

Convergent evolution

unrelated species have similar adaptations to similar environments.

Divergent Evolution or Divergent Evolution or adaptive evolutionadaptive evolution

Divergent evolution The evolution from a common

ancestor to a variety of species.

Example: Hawaiian honeycreepers

Divergent Evolution or Divergent Evolution or adaptive evolutionadaptive 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”

Over 99 per cent of the species that have ever lived have gone extinct.

• Extinction is the process in which groups of organisms (species) die out.