Prepared May, 2010
In Celebration of Psalm
God's handiwork in
and Formation of Dry Land
3.9 to 1.8 Ba
NOTE: Ba (Ma) = Billions (Millions) of years before the present time.
NOTE 1: see
the lecture A Fit Place to Live
for a synopsis of Chapters 5-??. The
and highly readable book by J. William Schopf, Cradle of Life treats
the material of this chapter in greater depth.
NOTE 2: This website follows the nomenclature established by
Margulis, Five Kingdoms.
Some biological systematists use the term "domain" where Margulis uses
the term "kingdom." Furthermore, we use the term "bacteria" for the
more formal term "prokaryotes" (kingdom prokaryota or eubacteria),
meaning single-celled species that lack a nucleus. Nucleated species
are eukaryotes, kingdom eukaryota[See Margulis, Kingdoms and Domains, p.9ff.].
I call eukaryotes "proper cells" which will be the subject of the next
The last chapter described
the state of the Earth
around 3.9 Ba, when it first became able to support a primitive sort of
life. Immediately bacterial life appeared in all of its essential
The earliest actual fossils that have survived undamaged
come from some 400 million years later, about 3.5 Ba. For the next
2 billion years (to about 1.8 Ba), bacterial life dominated the
world and caused major
transformations of the earth's surface and atmosphere. These changes
prepared the earth for the next great innovation: the
"proper" nucleated cell -- the kingdom of Eukaryotes, the subject of
the next chapter.
The Primordial Environment
Necessary Changes to Foster Advanced Life.
The first living material had to be strictly autotrophic,
(obviously) all of its food and energy had to come from inorganic
material. In modern usage the term "autotrophic" is used in a much
looser sense. often including plants and bacteria that utilize carbon
dioxide or sulphur rather than oxygen.
Just as importantly, the first living material had to have a
fixed nitrogen, which is a major component of organic food. The early
atmosphere was mostly nitrogen gas. The two nitrogen atoms in the gas
are very energetically bound. It takes a very large amount of energy to
separate ("fix") the atoms so they can be used biologically, usually as
ammonia, NH3 or the salt NH4OH. In the inorganic
world, these necessary products are rare and occur mostly as transient
byproducts of chance events such as lightning or volcanic activity --
not a stable or abundant source of nitrogen needed for the necessary
rapid proliferation of life
The early earth was strongly reducing, which means that free
not reliably available -- it would be sucked up in oxidizing nearby
minerals. Advanced life, particularly multicellular life, requires the
abundant availability of oxygen: there is no alternative to this. Thus
early life was limited to single-celled bacteria which could thrive in
a non-oxygen atmosphere.
Advanced life is too busy with other
to make its own food from scratch. Therefore
a major requirement for a global environment that supports advanced
life is that pre-processed organic food must be readily available
worldwide, together with a vast global distribution of bacteria to
produce it and break it down. This requires in particular, that fixed
nitrogen must be prepared in advance and readily available. In a word,
Advanced life cannot be autotrophic in the strict sense.
The early earth was covered with a global ocean -- hundreds
of feet deep -- so the first life thrived in a water medium. The water
distributed life and its products worldwide. The
tidal effects of a nearby moon and the continued cooling of the earth's
crust resulted in many large volcanoes whose debris often penetrated
the ocean surface to form volcanic cones, but these quickly eroded by
the violent tides and weather so that for many millions of years there
was nothing resembling permanent dry land. Eventually the
volcanic activity resulted in extensive, reasonably stable,
shallow-water tidal zones -- areas that were washed by the ocean and
tides but reliably remained within reach of sunlight.
Bacteria dominated the scene for over two billion years. In
(as we will see) it transformed the atmosphere from a reducing,
atmosphere, to an oxidizing one that has oxygen gas as a major
component. Towards the end of this period, the earth also began to form
permanent dry land, the ancestors of the continents that exist today.
Earliest Fossil Species.
Fossils, of course, exist in rocks that must be at least as
old as the
fossils, and that must have been preserved intact without being
deformed or subjected to extreme heat or pressure. There are very few
locations on the earth where such ancient rocks exist. A small amount
of such rock exists in Western Australia, and another place is portions
of Eastern South Africa near Swaziland.
Although there is evidence of life as far back as 3.9 Ba, the
actual fossils are closely dated to 3.465 Ba ± 5 Ma, disovered
by J. William Schopf. This close dating is possible because the fossils
are sandwiched between lava flows containing zircon crystals that can
be precisely dated[FOOTNOTE: Schopf, Fig.
3.4 p.77; "The Apex fossils are preserved in a chert
bed sandwiched between two massive lavas of the Pilbara sequence." p.
These early fossils appear in chains as depicted in the
See Op. Cit. Fig. 3.4 for
Sketch of earliest fossil (3.465 Ba)
They appear to be chains of
called blue-green algae. A
typical modern example is Anabaena, see Figure 2.
Photograph of Anabaena, a modern Cyanobacteria
Sketch of a Cyanobacteria chain.[FOOTNOTE http://www.biol.tsukuba.ac.jp/~inouye/ino/cy/36.gif.
by permission. For discussion of Anabaena Cyanobacteria see Lynn
and Kathlene V. Schwartz, Five Kingdoms: An Illustrated Guide to
Phyla of Earth,Third Edition, W.H. Freeman, 1999, p79. The most
recent edition of this work has been renamed Kingdoms and Domains (2009)].
Preservation of the first
fossils through almost 4.5 billion years of chaotic upheaval of the
earth's crust is practically a miracle. Almost all of the rock on earth
has been melted, compressed, distorted or otherwise changed in ways
that would destroy fragile fossil evidence. Schopf's book gives a vivid
description of what has to happen for these ancient fossils to survive
to the present day[FOOTNOTE: Get reference].
The result is that such fossils are found in only a few small location
worldwide: small areas in South Africa (Swaziland formation) and in
Western Australia. Indeed it is remarkable that there are any fossils
remaining from these ancient times.
In the example of Schopf's fossils they had to avoid being "cooked" by
lava flows both below and above the actual fossils -- a rare event
indeed -- but without this lava and the risk of overheating, the
fossils could not be dated.
I believe this is an example of the silent speech that God preserves in
his creation to declare his glory and handiwork.
Cyanobacteria are moss-like
species that live in
bathed in light, such as in shallow bodies of water. They are
complex, far from what one would think to call primitive. They grow in
long chains because when the cells reproduce they divide in half and
to remain attached. They secrete a kind of mucilage or slime which
to form characteristic multi-layered dome-like structures called
that grow in shallow water between high and low tide. Living
exist today in only a few locations worldwide, one being Hamelin Pool
Location of stromatolytes
The fossils appear to be a type of bacteria that formed stromatolytes,
which are found in ancient rocks worldwide. Stromatolytes grow in
highly saline tidal basins and are relatively rare today. An example of
modern living stromatolyte formations is found at Hamelin pool, a tidal
flat in Western Australia.
Stromatolytes at Hamelin Pool
Photo by Martin W. Peters,
used by permission
If the identification of
these fossils as cyanobacteria is correct (the
assumption here), then it immediately poses a problem because -- as we
will see -- cyanobacteia are advanced bacteria, not what one would
assume to be representative of the earliest living species[FOOTNOTE:
Schopf, ibid, p.78 "It seems
to me likely that several of the Apex species are cyanobacteria, a
fairly advanced group of microorganisms that until this find was not
guessed to be present so early in Earth history.].
Why bacteria and not
paleo-biologists insist that the earliest life was from the kingdom
Archaea (indeed the name
implies that they are the most ancient bacteria), based on the ability
of archaea to manage in very hostile environments (which the early
earth certainly was), and the claimed advantages of survival near deep
water thermal vents.
It is not the purpose here to confirm or deny this
there are some good reasons to doubt that archaea could "be fruit and
multiply and fill the earth"[FOOTNOTE: Genesis 1:22]
to the degree required at this point in the earth's history: Archaea
are too limited and specialized to fill that role. In addition, the
genetic make-up of the archaea appears to be more advanced than that of
bacteria, more akin to eukaryotes, and therefore (one would assume) a
later development. In the final analysis, though, it does not really
matter whether the first
living species were archaea; the first practical living species had to be
bacteria, and as a matter of fact, bacteria were the first fossils
preserved in the fossil record.
Preparation for advanced life.
The rapid multiplication of the early species of life was needed to
prepare the earth for more advanced species. Almost three billion years
separate the first fossils and the first eukaryotic fossils -- the
first step towards complex, multicellular life.
Looking ahead, the main tasks for the early bacteria were:
Distribute abundant amounts
of organic food worldwide.
- This task is needed because
advanced life cannot take the time or energy to be self-sufficient
• Convert the earth's atmosphere and the oceans from reducing
to oxidizing. The atmosphere must have around 20-25% oxygen content.
Complex life requires at least the lower limit of abundance, and the
upper bound is needed to avoid spontaneous combustion.
- In particular, this food provides fixed nitrogen, which is essential
for all of life. Its manufacture from atmospheric nitrogen is a
difficult, energy-consuming slow process (see below). No eukaryotic
species is able to manufacture nitrogen. In fact, very few bacteria
species are able to manufacture all of its own requirements for
The nitrogen may be either organic or inorganic (in the form of
nitrates or ammonia gas).
It appears that the limiting requirement was the oxygen
took the full
three billion years to achieve, with the aid of oxygen-producing
bacteria. The global distribution of the food supply, fixed nitrogen,
formation of vast mineral deposits that are so essential to the
modern technological age were by-products of
this push to develop the oxygen supply.
the first living species. Cyanobacteria
are apparently the bacteria of choice in this
task because they produce oxygen as a "waste" byproduct of
photosynthesis. One problem is that cyanobacteria
are complex -- in Margulis' classification they are phylum B-6, about
half-way up the ladder of bacterial complexity. This
in such ancient species is something that evolutionary
theory would not have predicted.
using solar energy to energize life processes -- involves interactions
between many individually complex molecules. Photosynthesis requires
the use of a closed membrane that can enclose an acidic interior
(excess H+) to drive ATP production. The chlorophyll and ATP
synthase molecules are embedded in this membrane.
similarities between all photosynthetic systems and its complexity is
such that evolutionists such as Stephen Jay Gould assert that it could
only have evolved once, which means (in his lingo) that it is a very
low probability result of random processes.[FOOTNOTE:
According to an
analysis of the cyanobacterial genome (Hasselkorn and
Johnston (PNAS)) the earliest cyanobacteria
already had the light & Calvin processes for
photosynthesis in place. These are two very complex and subtly linked
processes and involve many specialized molecules working together.
These are such complex biological processes, that the complexity and
early appearance on earth seems to indicate planning and design.
Biologists universally (as far as I am aware) point to the complexity
and the similarity of photosynthesis among all species to imply that
the process evolved only once in earth's history[FOOTNOTE:
for example, Schopf p. ???; other references] -- the
chance events that had to occur for photosynthesis to arise even once
by natural processes are vanishingly low probability, so that assuming
the same system would arise more than once defies even an
Photosynthesis divides into
two parts: the light process and
process. In the light
process, chlorophyll uses the energy of
sunlight to produce ATP and NADPH. Each of these processes involves
complex molecules: ATPsynthase (a molecular motor described in the last
chapter) and NADP reductase. The dark
process, also called the Calvin cycle then
uses these products to form triose sugar (C3H6O3)
with the help of another complex molecule
(RuBisCo). The triose sugar is used to form
starch, amino acids and sugars.
Photosynthesis: Light Process
ATP provides energy to the dark process and to the cell generally
NADP is an H carrieer enzyme used in the dark process.
In cyanobacteria photosynthesis occurs in a thylokoid membrane.
Process Animation [FOOTNOTE: From Virtual Cell Animation
Photosynthesis: Dark Process
5 of 6 triose sugars are re-used in the cycle.
All cyanobacteria use the Calvin cycle.
[FOOTNOTE: Hasselkorn, Johnston].
The chlorophyll molecule of
species captures light
energy using a special ring structure that has a magnesium atom
suspended between four nitrogen atoms. When light hits this structure,
a high energy electron is emitted and its energy initiates the
The hydrophobic tail is embedded in a membrane.
The magnesium complex captures light.
TODO: Discuss the special
molecules and the genetic machinery to
construct them. See The
Cyanobacterial genome core and the origin of photosynthesis
(Proceedings of the National Academy of Sciences, 2006).
nitrogen made up about 80% of the ancient earth's atmosphere, it cannot
be used to fill every living cell's need for nitrogen. As one author
remarked, "No animal, plant, fungus, or protist has mastered the
chemical art of converting the abundant gaseous form of nitrogen into a
biologically useful one."[FOOTNOTE: David W. Wolfe, Out
of Thin Air - nitrogen fixers, Natural History, Sept. 2001.
Note that he suggested a source of nitrogen from lightening forming
Nitrate, but this is not possible because the early atmosphere was
almost entirely oxygen-free. See Schopf, p. 153]
had to fix
nitrogen; that is, convert atmospheric nitrogen to amonia;
otherwise life could not flourish. There was no other effective way to
get the nitrogen needed[FOOTNOTE:
p 153 "Today, large amounts of nitrate are made
when oxygen and nitrogen combine during lightening storms, but this
could not happen in the early oxygen-deficient atmosphere.... The
scarcity of ammonia and nitrate posed a major problem to life." Also
see NAS studies].
Only one way to fix nitrogen exists in nature, and that is
with the use
of the complex nitrogenase
motor molecule. Nitrogen fixing
is a very slow
process. To convert a single molecule of nitrogen gas to ammonia, the
molecule, which is made up of two giant proteins, must physically
and rejoin eight times, and this takes about 1.2 seconds. Today,
nitrogen fixing worldwide only supplies 10-20% of life's annual
consumption. The rest must come from recycled organic food (or, in the
past century, from commercial inorganic nitrogen).
Nitrogenase molecule, illustrated in Figure 5 has
and is composed of two proteins involving a molybdenum and magnesium
atoms, called MoFe (dinitrogenase) and FeMo-co (MoFe cofactor). MoFe is
produced by the genes nifD and nifK. All told some 22 genes are involved
in producing and regulating the molecule. A full explanation of how
nitrogen fixation works is still unresolved.
The formula for nitrogen fixing by the nitrogenase molecule
N2 + 8 H+
+ 8 e− + 16 ATP → 2 NH3 + H2 + 16 ADP
+ 16 Pi
where Pi denotes an
inorganic phosphorous compound. This is a formal
equation only: other than with the use of the nitrogenase molecule as a
catalyst, there is no known way to execute the equation at normal
ambient temperature and pressure in any chemistry laboratory. The
formula indicates that 16 ATP molecules are reduced to ADP to supply
the energy to produce 2 ammonia atoms. This is very expensive
energy-wise, as well as very slow.
The only commercial way to fix nitrogen is by using the Haber process,
which operates at high temperature and pressure[FOOTNOTE:
pressure 2250-4000 psi. and temperature 300-550°C.],
and so cannot be duplicated in the biological world.
A cell that fixes nitrogen is called a diazotroph. The
irony is that such a cell that fixes nitrogen cannot produce enough
nitrogen to meet its own needs. Typically, the fixed nitrogen is
released from the diazotroph as a waste product rather than used
directly for its own needs. In exchange, the cell receives the bulk of
its own nitrogen needs from food which it receives from its
surroundings. So the typical nitrogen-fixing bacteria live in a
symbiotic relationship with a normal cell and exchange food for fixed
nitrogen. [QUESTION: TRUE? HOW MANY NITROGENASE "FACTORIES" ARE
IN OPERATION IN A TYPICAL FIXING CELL AND WHAT THROUGHPUT? ANSWER THIS:
A CELL NEEDS ABOUT ??? NITROGEN ATOMS AND PRODUCES ABOUT ??? FIXED
NITROGEN ATOMS PER UNIT OF TIME.]
also very scarce. All the world's supply of nitrogenase could be
in a single bucket[FOOTNOTE: David W.
Wolfe, Tales from the Underground: A Natural History of
Life, Perseus, 2001, p. 78; Huxtable, Reflections: Fritz Haber (regarding
the Haber process whish is the only inorganic way to fix nitrogen).].
not surprising that nitrogen-fixing bacteria had to work for billions
years to make enough nitrogen available for higher plants and animals
thrive. It was a vital task for the early cyanobacteria, along with
building the earth's supply of atmospheric oxygen.
There is an irony here: It was vital that cyanobacteria
but oxygen is lethal to the nitrogen-fixing process[FOOTNOTE:
Schopf, p153, "The
ferredoxin-driven [nitrogenase] complex dates from early in Earth
history when the environment was all but oxygen-free... [It] is brought
to a standstill by trace amounts of molecular oxygen. N2-fixation
happens only if O2 is shut out, even in oxygen-producing
cyanobacteria....".]. The solution is that the
cyanobacteria had to conduct nitrogen-fixing in a specialized cell,
called a heterocyst,
that was isolated from the photosynthetic
activity. The heterocyst has a thick wall to isolate its contents, and
it is dependent on other cells for food and energy, which it needs in
abundance. In a typical nitrogen-starved medium, about one in 15 cells
in a (modern) cyanobacteria chain is a heterocyst (Figure 6).
Fixing and Nitrogenase
A method to fix
nitrogen was absolutely critical for the early species to fluorish on
the early earth; otherwise life at best could only falter along using
the scarce fixed nitrogen found naturally. A major task of this early
life was to spread fixed nitrogen as food worldwide so that it could be
used by more advanced life, and so it had to have an abundant supply.
There appears to be only one way to fix nitrogen naturally, and that is
with the use of the complex nitrogenase molecule. The
nitrogenase molecule is so complex that to date (2010) the procedure
that it uses is not fully understood. In any case the process is very
slow (taking 1.3 seconds to fix a single nitrogen molecule), and
requires not only a very complex molecular process, but it also
requires a specialized cell in which oxygen is excluded.
How is such a molecule to be developed by purely natural, undirected
processes? As with photosynthesis, the molecule is so complex and
unique that it is inconceivable that the molecule could have arisen
naturally more than one time in the history of life -- and I would
argue that it stretches credulity to think that it could have arisen
even one time without a creator's hand.
By permission of David Webb
SHARP POINT: Nitrogenase
also produce another specialized cell called an akinete, which can
survive under harsh conditions -- freezing,
dehydration -- for long periods of time. Since the early earth was
constantly changing with no permanent dry land or shorelines, the
ability to survive and resume growth in another locality or time was
important. In addition the ability to go into a kind of suspended
existence also allowed the cyanobacteria to drift with the ocean
currents and distribute life and nutrients worldwide.
describe the form/interdependence of the colonies. Multiple
SHARP POINT: THE ARRIVAL OF
EUKARYOTES AT JUST THE RIGHT TIME [MOVE TO NEXT CHAPTER].
[CHECK THE CHEMISTRY IN THE FOLLOWING]
Life's Early Boom and Bust
Formation of Uranium and Iron Ore Deposits. Because the early
earth was starved for oxygen, the ocean held abundant amounts of
reduced salts in solution. The oxygen produced by the early
cyanobacteria combined with these reduced salts. If the product was
(relatively) insoluble, it precipitated out, forming over time vast ore
Uranium salts were among the first to oxidize because
reason]. The product, UO2 (pitchblende) is virtually
insoluble and so as the salts oxidized the product precipitated out,
forming the uranium ore deposits. This continued for about a billion
years, until most of the uranium salts were fully oxidized.
For the next
billion years, silicon and iron soaked up the excess oxygen,
and the great iron ore deposits. The precipitation of silicon and
iron is sensitive to the acidity
of the environment. When acidity is high, silicates remain dissolved in
the ocean water, but iron oxide precipitates. When acidity drops, the
precipitate out. These boom and bust cycles can be seen in a geological
record known as the banded iron formations.
The banded iron formations
end at about 1.5 Ba, when most of these elements in the ocean and
exposed crust are
oxidized, and the next great biological invention -- eukaryotes --
appears on the scene. Afterwards, the oxygen rose to a fairly stable
20-25% level in
atmosphere, where it has remained ever since. The stability is the
result (???CHECK) of an ecological balance between oxygen-consuming and
carbon dioxide-consuming species.
You may immediately see a potential problem:
oxygen is generally
poisonous to the bacteria that are the only life on earth. As long as
were minerals to draw off the excess oxygen, things could go on. But
the earth's crust is fully oxidized. What is going to keep the oxygen
growing to the point where life hits a stagnant and unfruitful plateau?
We will see the answer next.
The changes in acidity reflect the changing fortunes of the
oxygen-producing biological material in the oceans. When the bacteria
thrive they produce an over-supply of oxygen which poisons the
environment and causes the bacteria to die out. When the over-supply is
absorbed by reduced salts, the bacteria recover and once again
over-produce oxygen. Ultimately the problem is that there is not enough
oxygen-consuming biological material to provide a biological balance:
the arrival of eukaryotes will resolve the imbalance. This is the
subject of the next chapter.
Banded Iron Formation
iron oxide (Fe2O3) = dark
and silica (SiO2) = light.
The Appearance of Dry Land. For the
first two billion years, the earth had no permanent dry land. Frequent
volcanoes caused ashes and debris to form volcanic cones that would
penetrate the ocean surface, but these cones were not permanent because
storms and tidal activity eroded them over time. The final result of
these temporary penetrations of the ocean surface was the formation of
extensive shallow tidal areas that became homes for extensive
shallow-water species including the cyanobacteria and other bacteria
that formed extensive beds containing stromatolytes.
When the earth cooled from a molten state, its interior
formed strata (Figure 8), with a heavy nickel-iron core mixed (and kept
hot) with a low
concentration of other heavy radioactive metals and their daughter
products. Layers below the crust are in a plastic or semi-liquid state,
maintained by pressure and radioactive heat[FOOTNOTE:
Without radioactive heating, the Earth's interior would have cooled
because of radiation to space, over a time on the order of a hundred
million years. This realization was a great puzzle to scientists until
the discovery of the heating potential radioactive decay in the early
1900s. See Lord Kelvin [GET REFERENCE]]. The layered
structure of the earth has been confirmed by analysis of global
acoustic sound transmission (seismology) conducted over many years. The
most recent analyses use a form of tomography (similar to the
techniques used in medical imaging) to reconstruct the form of the
The interior heat gives rise to convection currents in the Earth's
Mantle, energized by the heat emitted by the (semi-solid) core (Figure
9a). These currents carry along the earth's crust, which fractures at
collision and separation points.
crust broke up into a number of large plates that were carried along by
subduction currents in the mantle (Figure 10). These collided, causing
one plate to
pass under an adjacent plate. This is called subduction. The edges of
the plates that end up underneath in the collision are
carried along by the mantle currents deep into the mantle itself. As
this happens, the sinking edges of the plates melt from the heat.
with a lower melting point melts first. This also happens to
a lower density, and as it melts, it rises through cracks, leaving
denser matter behind. Over time the lighter material forms the
continents which, because of their lower density, literally float atop
the mantle. As the continental mass builds up, it rises above the ocean
surface and the result is permanent dry land. This process is called plate tectonics[FOOTNOTE:
For an interesting account of plate tectonics, see "Plate
Tectonics in a Nutshell" by the
U. S Geological Survey.]
Mantle Convection Currents
Present Day Currents
An example of this subduction is along the
western coast of South America, forming over
the South American continent and the Andes mountains.
Figure 11 shows a map of the tectonic plates at the present time.
Volcanic activity tends to follow the plate boundaries.
Present Day Tectonic Plates
Showing Active Volcanic Zones
Where mantle currents diverge, the crust separates, causing newly
formed crust to form under the oceans. The mid-Atlantic ridge is an
example of such a divergence. The newly formed material is basalt.
Recently formed material (within the past 600 Ma)
underlays most of the ocean floor. It is denser
than continental rock.
Dry Land and Land Plants
THE GENESIS ACCOUNT
Creation Day 3
Genesis 1:9-13 (ESV)
9 And God said, “Let the waters under the
heavens be gathered together into one place, and let the dry land
appear.” And it was so. 10 God called the dry land Earth, and the
waters that were gathered together he called Seas. And God saw that it
11 And God said, “Let the earth sprout vegetation, plants yielding
seed, and fruit trees bearing fruit in which is their seed, each
according to its kind, on the earth.” And it was so. 12 The earth
brought forth vegetation, plants yielding seed according to their own
kinds, and trees bearing fruit in which is their seed, each according
to its kind. And God saw that it was good. 13 And there was evening and
there was morning, the third day.
DAY THREE. The
record shows that the creation of dry land began around 2 Ga. with the
formation of what would become the continents. The geological
record agrees completely with the Genesis account in the fact that the
initially covered with water and that the dry land was made to appear
out of the waters. This happened by forming
the continents of less dense granites and other materials by the
process of fractionation that is described above. Both the
less dense continental rocks and the denser magma that forms ocean
floor and underlays the continents float together on the fluid mantle
with the result that the continents rise above the ocean surface much
as icebergs float on the oceans.
This is a physically stable and permanent arrangement. The opposing
tendencies of weather and water erosion and dry land formation achieved
an equilibrium by about 600 Ma, and then the tectonic plate
movements gradually moved the continents to the present configurations
forming the seas, all of which connect with each other into a single
The tectonic forces that create the
continents also lead naturally to the formation of mountain ranges
collision lines of the plates (and abyssal depressions where they
separate). The mountain ranges have a beneficial effect in climate
control since the prevailing westerly winds precipitate rain as they
rise over the mountains.
The "earth sprouting vegetation" -- creation of seed plants, fruit
trees, etc., was a long process that started with microscopic life but
the full-fledged creation of air-breathing plants: grasses (a more
literal translation of "vegetation"), and eventually fruit trees,
required one major innovation, namely the ozone layer in the high
atmosphere, to shield exposed plants from damaging cosmic rays. This
layer began to form once the oxygen content of the atmosphere
stabilized at around 20%, but it took until about 300 Ma to develop
fully. Thus the second half of the creation recorded in Day Three
really took off by around 300 Ma, and overlaps with the creation of sea
animals in Day Five.
Reactions (at 300°K)
of the third phosphate group by hydrolysis: ATP + H2O → ADP
is the standard source of energy for most bioloical activity. Pi
denotes an inorganic phosphate (-PO4). The exact energy
depends on the particular reaction. See Alberts et al. Essential Cell Biology, Ch. 3
-> 2 H+
-> 2 O+
reactions that break down Oxygen take less energy than indicated here
because they exchange the oxygen bond for other bonds.
-> 2 N+
has one of the highest bond strengths. As a result, nitrogen fixing is
a very energy-intensive process. The usual end product of nitrogen
fixing is ammonia (NH3).
(mid-infrared) Thermal energy (300°K)
Wikipedia Article, Bond
dissociation energy (Bond Strength);
Handbook of Physics and Chemistry, (60th Ed 1980)
of diatomic molecules, table 1, pg F-220ff.
* Morowitz, Table 12.
Note: 23.065 Kc/Mole = 1.000 ev.
|Archaeobacteria are more advanced than
One argument against the view that archaeobacteria were the first form
of life is that archaeobacteria appear to be more advanced than other
bacteria. For example, the ribosomes of archaeobacteria look like
eukaryotic ribosomes and they differ considerably from bacterial
ribosomes, as shown in the following sketch[FOOTNOTE: Source: Margulis,
Kingdoms and Domains,
TODO: Compare the ribosome construction and function.
Bruce Alberts, et al. Essential Cell Biology: An Introduction to
the Molecular Biology of the Cell
David C. Bossard, A
Fit Place to Live
S. Broecker, How to Build a
Guillermo Gonzalez & Jay W. Richards, The Privileged Planet
Robert Hasselkorn, The
Cyanobacterial genome core and the origin of photosynthesis
(Proceedings of the National Academy of Sciences, 2006)
D. T. Johnston et al, Anoxygenic
photosynthesis modulated Proterozoic oxygen and sustained Earth's
(Proceedings of the National Academy of Sciences, 2006)
and Kathlene V. Schwartz, Five Kingdoms: An Illustrated Guide to
Phyla of Earth,Third Edition, W.H. Freeman, 1999, p79. The most
recent edition of this work has been renamed Kingdoms and Domains (2009) by
Lynn Margulis and Michael J. Chapman.
Harold J. Morowitz, Beginnings of cellular Life,
J. Willliam Schopf, Cradle
of Life: The Discovery of Earth's Earliest Fossils
Peter D. Ward & Donald Brownlee, Rare Earth: Why Complex Life is Uncommon
in the Universe.
Prepared May, 2010