Thermal History of the Earth and
Biosphere
PALEOTEMPARATURES
Indiana University
PALEOTEMPARATURES
Sigman, D.M.; E.A. Boyle (October 2000).
"Glacial/interglacial variations in atmospheric carbon
dioxide" Nature 407 (6806): 859–869.
CRUST HARDENS; GLOBAL OCEAN FORMS
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Planet has cooled enough
that surface temperature
allows condensation
Atmosphere is full of an
ocean of water vapor
100,000 yrs of rain….
No land above water; crust
is below water, in what are
now ocean basins
Hot/warm water, high
energy, soup of chemicals
EVIDENCE OF LIFE: WHAT TO LOOK
FOR?
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Chemical footprints
Isotopes of carbon
What kind of material
can survive extreme
heat? Zircons, “shields,”
greenstones…
West Antarctica,
Greenland, W. Australia
Organic rich meteorites –
organic molecules for
first life from space?
The
MillerUrey
experime
nt
ORIGINS OF MICROORGANISMS
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Bacteria-like organisms have existed on earth for about
3.5 billion years
 Prokaryotes (pre-nucleus): Simple cells
 Eukaryotes (true nucleus): Complex cells
7
1. The earth was formed ~4.5 billion years ago
2. It took ~500 million years for the crust to
solidify.
3. The oldest fossils of microorganisms
• 3.5 billion years old,
• embedded in rocks in western Australia
3a. Prokaryotes dominated from 3.5 to 2
billion years ago.
- During this time, the first divergence
occurred:
Early and modern prokaryotes
DIAMONDS ARE MADE FROM DEAD
BACTERIA???
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Carbon, the main component of most diamonds, usually
contains an isotope of light carbon (12C), which is utilized by
some living organisms.
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Therefore, eclogitic diamonds with large amounts of the
isotope 12C, are believed to have an organic origin.
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These were formed from carbon near hydrothermal vents
which was also utilized by the bacterial communities near
the vents.
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Thus through time, heat and pressure were able to turn the
carbon along with the bacterial colonies into diamonds.
"So, those sparklers of yours may just be clumps
of billion-year-old bacterial corpses"
FACTS ABOUT MICROBES
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Microbes outnumber all other species and make up most
living matter (~60% of the earths biomass).
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Less than 0.5% of the estimated 2 to 3 billion microbial
species have been identified.
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Microbial cycling of critical chemical elements such as
carbon and nitrogen helps keep the world inhabitable for
all life forms.
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Underground: Chemolithotrophs found in Basalt deposits 1500m
(4700 ft) underground in solid rock.
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The Sky: Some bacteria spend their whole lives in the atmosphere,
growing and reproducing in the clouds above our heads.
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On Ice: Some bacterial species live in the ice of glaciers and others
have often found in the snows of the North and South poles at -17
and -85°C.
PERMIAN SALT LAYERS (SALT MINE IN
BERCHTESGADEN, GERMANY), CA. 250
MILLION YEARS OLD
Haloarchaeal isolates from Permo-Triassic salt
HALOCOCCUS SALIFODINAE DSM
8989T (FOUND IN ALPINE AND
ZECHSTEIN DEPOSITS)
Halococcus dombrowskii
T
DSM 14522
Extraterrestrial halite
SNC-Meteorites (from Mars; Shergotty, Nakhla Chassigny)
Murchison meteorite (from asteroid belt)
Monahans meteorite (from asteroid belt)
salt pools on the surface of Mars
ocean on the Jovian moon Europa
Enceladus (moon of Saturn) geysirs
Red and blue sodium
chloride crystals
in the Monahans
meteorite. Each
picture is 1 mm in
width.
.
Antarctica, 1984
Contd…
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Not So Cool: Some bacteria have learned to live in hot springs.
Some species are happy at 75°C while others think even this is
cool. Species of Aquifex can live in water as hot as 95°C. Archaea
are happy to grow deep sea hydrothermal vents at 106°C
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The Deep Sea: Bacteria ‘known as Extreme Barophiles’ live at
depths of >10000 m and are able to survive pressures in excess of
1000 times the air pressure at sea level; and they cannot function
properly at pressures less than 400 atmospheres and may die in a
couple of hours if brought to the surface.
This 4.5 billion-year-old rock, labeled meteorite ALH84001, is believed to have once been
a part of Mars and to contain fossil evidence that primitive life may have existed on Mars
more than 3.6 billion years ago. The rock is a portion of a meteorite that was dislodged
from Mars by a huge impact about 16 million years ago and that fell to Earth in Antarctica
13,000 years ago. The meteorite was found in Allan Hills ice field, Antarctica, by an annual
expedition of the National Science Foundation's Antarctic Meteorite Program in 1984. It is
preserved at the Johnson Space Center's Meteorite Processing Laboratory in Houston.
THERE'S A "SLEEPING BEAUTY"
STORY FOR BACTERIA?
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In May 1995, scientists were the prince as they revived
25-40 million year-old bacteria from the stomach of a
bee that was preserved in tree sap.
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It was this event that led to the notion of Spielberg's
Jurassic Park, where dinosaurs were created after
their DNA was extracted from mosquitoes trapped in
tree sap the same way.
“The dinosaurs, however, were the ones who took the limelight
away from the bacteria on the movie screens”
SERGEI WINOGRADSKY (1856-1953): THE
CONCEPT OF CHEMOLITHOTROPHY
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Interested in bacteria involved
in the cycling of nitrogen and
sulfur
Introduced the concept that
bacteria could be important
biogeochemical agents
SERGEI CONT.
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From studies on sulfur-oxidizing
bacteria:
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Chemolithotrophy: the oxidation of
inorganic compounds linked to energy
conservation
From studies on nitrogen fixing
bacteria, concluded that they
obtained their carbon from CO2
From studies, proposed these
organisms were autotrophs,
specifically chemoautotrophs
Also isolated the first nitrogen-fixing
bacteria
Microbial world
Organisms
Infectious agents
(non-living)
(living)
Prokaryotes
(unicellular)
Eubacteria
Archaea
eukaryotes
Algae
(unicellular
or
multicellular)
viruses
viroids
prions
Fungi
Protozoa
Other
(unicellular
(unicellular) (multicellular
or
organisms)
multicellular)
ARCHAEA
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Domain Archaea with 3 kingdoms:
2.7 Ga molecular data (Australia)
3.8 Ga organic matter = chemical fossils?
Methanogens
Thermophiles
Halophiles
DIVERSITY OF SKELETAL COMPOSITIONS
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*Aragonite
*Calcite
*Mg-calcite
*Opalline silica
*Apatite
*Organic
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Chitin
Cellulose
Others
*Arenaceous/agglutinated
Rare minerals
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Celestite (Sr sulfate)
Magnetite
Rhodocrosite (sp?)
The size and cell type of microbes
Microbe Approximate range of
sizes
Cell type
Viruses
0.01-0.25µm
Acellular
Bacteria
0.1-10µm
Prokaryote
Fungi
2µm->1m
Eukaryote
Protozoa
2-1000µm
Eukaryote
Algae
1µm-several meters
Eukaryote
STROMATOLITE-BUILDING COMMUNITIES
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rock-like buildups of microbial
mats that form in limestone
include oldest known fossils,
3.5 bya
encode role ancient
microorganisms played in
evolution of life and shaping
earth's environments.
Extensive fossil record of
stromatolites; spans 4 by of
geological history; occupied
every conceivable environment
that ever existed.
Today, nearly extinct in marine
environments, living a
precarious existence in only a
few places worldwide.
Modern stromatolites
discovered in Shark Bay,
Australia in 1956
STROMATOLITES – OXYGEN EXCRETING “COLONIES”
POPULATED EARTH
4. Oxygen began accumulating in the
atmosphere about 2.7 billion years ago.
a. Cyanobacteria are photosynthetic
prokaryotes that are still present today 
produced oxygen.
Banded iron formations are evidence of the
age of oxygenic photosynthesis –
By comparing ancient stromatolites with modern stromatolites, it
has been concluded that filamentous phototrophic bacteria, perhaps
relatives of the green nonsulfur bacterium Chloroflexus, formed
ancient stromatolites.
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• Early Earth was anoxic and much hotter than the
present Earth. The first biochemical compounds were
made by abiotic syntheses that set the stage for the
origin of life.
PRIMITIVE LIFE: THE RNA WORLD AND
MOLECULAR CODING
The first life forms may have been self-replicating RNAs (RNA life).
These were both catalytic and informational. Eventually, DNA became
the genetic repository of cells, and the three-part system—DNA, RNA,
and protein—became universal among cells (Figure 11.5).
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Possible mechanileifsm of evolution of life
Energy generating scheme for primitive cell
Oxygenic photosynthesis led to development of banded iron
formations, an oxic environment, and great bursts of biological
evolution (Figure 11.8).
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Landmarks of biological
evolution
5. The oldest eukaryotic fossils are ~2 billion
years old.
a. Symbiotic community of prokaryotes
living within larger prokaryotes.
 Mitochondria and chloroplasts
6. The oldest fossils of multicellular
organisms are ~1.2 billion years old.
ENDOSYMBIOSIS THEORY
(LYNN MARGULIS, 1970’S)
EUKARYOTIC ORIGINS
A. Invagination of plasma membrane
 B. Endosymbiosis
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 Symbiosis
: An ecological relationship between
organisms of 2 different species that live together
in direct contact.
 How did this get started?
 prey
or parasite
• Mitochondria arose from
the Proteobacteria, a
major group of Bacteria.
• Origin of the modern life
7. The oldest animal fossils are ~700 million
years old.
a. Animal diversity exploded ~540 million
years ago.
Fossilized animal embryos from
Chinese sediments 570 million years
8. Plants, fungi, and animals began
colonizing land ~500 million years ago.
a. First plants transformed the landscape…
b. Then animals were able to take
advantage of new niches
 Mammals evolved 50 to 60 million years
ago.
Self replicating
entities
on earth
METHODS FOR DETERMINING
EVOLUTIONARY RELATIONSHIPS,
EVOLUTIONARY CHRONOMETERS,
The phylogeny of microorganisms is their evolutionary
relationships.
•
• Certain genes and proteins are evolutionary
chronometers—measures of evolutionary
change. Comparisons of sequences of
ribosomal RNA can be used to determine the
evolutionary relationships among organisms.
SSU (small subunit) RNA sequencing is synonymous with 16S or
18S sequencing.
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• Differences in nucleotide or amino acid sequence of
functionally similar (homologous) macromolecules are
a function of their evolutionary distance.
• Phylogenetic trees based on ribosomal RNA have
now been prepared for all the major prokaryotic and
eukaryotic groups.
• A huge database of rRNA sequences exists. For
example, the Ribosomal Database Project (RDP)
contains a large collection of such sequences, now
numbering over 100,000.
Ribosomal RNA
Universal phylogenetic tree
Life on Earth evolved along three major lines, called
domains, all derived from a common ancestor.
•Each domain contains several phyla.
•Two of the domains, Bacteria and Archaea, remained
prokaryotic, whereas the third, Eukarya, evolved into the
modern eukaryotic cell.
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CHARACTERISTICS OF THE DOMAINS OF LIFE
Although the three domains of living organisms were originally
defined by ribosomal RNA sequencing, subsequent studies have
shown that they differ in many other ways.
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• In particular, the Bacteria and Archaea differ
extensively in cell wall and lipid chemistry (Figure
11.18) and in features of transcription and protein
synthesis (Table 11.2).
It has been proposed that a prokaryote whose 16S
ribosomal RNA sequence differs by more than 3% from
that of all other organisms (that is, the sequence is less
than 97% identical to any other sequence in the
databases), should be considered a new species (Figure
11.25).
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Relationship between 16S ribosomal RNA sequence
similarity and genomic DNA:DNA hybridization