Message from the Oklahoma State Textbook Committee:
This textbook discusses evolution, a controversial theory, which some scientists present as scientific
explanation for the origin of living things, such as plants and humans.
No one was present when life first appeared on earth. Therefore, any statement about life's origins
should be considered as theory, not fact.
The word evolution may refer to many types of change. Evolution describes changes that occur within
a species. (White moths, for example, may evolve into gray moths). This process is micro evolution,
which can be observed and described as fact. Evolution may also refer to the change of one living
thing into another, such as reptiles into birds. This process, called macro evolution, has never been
observed and should be considered a theory. Evolution also refers to the unproven belief that random,
undirected forces produced a world of living things.
There are many unanswered questions about the origin of life, which are not mentioned in your
textbook, including: Why did the major groups of animals suddenly appear in the fossil record, known
as the Cambrian Explosion? Why have no new major groups of living things appeared in the fossil
record in a long time? Why do major groups of plants and animals have no transitional forms in the
fossil record? How did you and all living things come to possess such a complete and complex set of
instructions for building a living body? Study hard and keep an open mind. Someday you may
contribute to the theories of how living things appeared on earth.
Evolution remains at the center of controversy in many
communities.
Oklahoma, Alabama, Kansas, Virginia are some of the states
that have taken political action to devalue this theory in
science education
Here’s the approved statement for biology textbooks in
Oklahoma (1999):
Theory is the basis of science
Theory is necessary because it is impossible to observe all
systems in all places at all times (as you are reading this you
are theoretically generating a myriad of proteins – this is
theoretical, because you are not actually evaluating your body
chemistry).
“Fact” or “Truth” is the goal of every Scientific Theory
Some Theories have more lines of evidence
The evidence for the Theory of Plate Tectonics comes from
a number of places and times, over several length scales.
As of now, we have only one example of the origins and
development of life. Models built on one example can be
internal consistent, but not externally verifiable.
What of life’s origins
Science
•The Earth has rocks that yield radiometric dates of 4 Ga, and is
routine struck by meteorites with dates of 4.5 Ga
•Remains of life are found in rocks 3.5 Ga and younger
•Remains start simple, become more complicated over time
Non Science
•My belief and value system holds a religious text to be literal and
inerrant. Therefore, our perception of old life on the Earth is
incorrect.
Pseudoscience
•Scientific discovery should prove my beliefs to be true.
•All inconsistencies with my preconceived notion must be wrong.
If you believe in the Genesis account recorded in
Judeo-Christian scripture as literal natural history
The correct is response is:
The Earth may look old and life may look interrelated, but I
believe life developed from a supernatural source
(a non-science philosophy)
Not:
The Earth does not appear old and/or life does not appear
interrelated, and I will attempt to use natural processes to
show how the supernatural act occurred.
(a pseudoscience philosophy)
The latter is the modus of so-called “creation science” and
“intelligent design”: which typically call on unique physical
processes to maintain a consistency with the Genesis text.
Message from Dr. Price:
This lecture discusses evolution, a scientific theory, much like the theories developed for gravitation,
electrical conduction, magnetism, the parts of an atom, covalent bonding, the dissolution of ions, plate
tectonics, lithification of sediments, grain boundary energy, the interaction of trophic systems, genotypes,
and protein synthesis. In each case, explanations are made to explain observations; these are tested
repeatedly and refined such that each approaches universality (applicable anywhere at any time).
No person was present when life first appeared on earth some 3 or more billion years ago. However, an
extensive record of the remains of ancient biota are preserved within the rocks of the near-surface of the
earth. The oldest demonstrable fossils are morphologically similar to modern unicellular life. With
increasing time, the diversity of life increases substantially: fossils record more complicated multicellular
organisms, and fossils become increasingly prominent in rocks formed subareally as well as those formed
in aquatic environments.
Perhaps more substantially, all life on earth shares common characteristics and chemistry. All living
things contain long chains of deoxyribonucleic acid that interface with ribonucleic acid to produce
complex molecules, called proteins, out of 20 amino acids. Changes in the sequence of deoxyribonucleic
acid occur through several processes; such changes can be dramatic on relatively short time scales, and
are logically thought to be extensive when considering geologic time. All living things respire and regulate
respiration, grow, respond to stimuli, and may reproduce. Changing conditions, such as the result of a
dynamic lithosphere, hydrosphere, and atmosphere, largely fueled by the nonrandom conditions of
imposed by a cooling planet revolving around a planetary body massive enough to fuse hydrogen into
helium, may support certain genetic codes at the expense of others.
There are many unanswered questions about the origin of life, which are not answered by our current
understanding of the Earth, including: Why did life become rapidly diverse in rocks dating from 540 million
years ago? What is the nature of transition in life diversity? How did you and all living things come to
possess such a complete and yet simple sequential set of instructions for building a living body? Study
hard and keep an open mind, and actually learn how to evaluate observations scientifically. Someday you
may contribute to the theories of how living things appeared on earth.
So, my disclaimer (based on the one for Oklahoma):
In short: creation science and intelligent design
are not science - they are philosophies
They have no legitimate place in a science
class.
Domains of Life
Analyses of
DNA make it
suggest that
all of life on
Earth is
related back
to one
single
organism.
Chemically,
we’re all
very similar.
The remnants of many organisms are left behind in
accumulating sediments. Skeletal materials, made of dense
minerals can be particularly well preserved. In places entire
ecosystems are buried and lithified.
Note: these are categorized by morphology and environment (not
genetics)
Q: what type of rock is this?
Keep in mind the fossil record is by no means an accurate
depiction of ancient life
Fossilization favors Organisms
with simple skeletons (few pieces)
in aquatic environments with rapid depostion
that are small enough to buried quickly
that are abundant and well distributed
that existed over substantial periods of time
Note the oldest observed fossil certainly may not be the oldest individual
for that organism
Note fossils contain no organic materials; there is only a little chemical
evidence to be gleaned from them.
The Moon shows evidence of heavy bombardment up to 3.8 Ga
Undoubtedly, the Earth is being impacted simultaneously – the
impacts would make the surface of the Earth unsuitable for liquid
water. Life is not likely to arise until frequent impacts cease.
Or maybe not…
Recent evidence shows that
the oldest materials on earth,
Jack Hills Zircons, are 4.4
biliion years old.
These record crystallization
temperatures in the 600-750
ºC range - implying wet
magmatic conditions and the
possible establishment of the
hydrosphere.
NASA’s Earth Observatory
But prior to 4.4 Ga, there are a number of problems
with the early Earth.
•Very hot
•Frequent inputs of high kinetic energy
•Weak atmosphere
•Sunlight reduced at surface
•No liquid water at surface (and little fluid water at
depth)
•No complex organic molecules
All except last are reduced through gravitation and
kinetics. The last is trickier although helped by cooling
temperatures.
In 1953, Miller and Urey
conducted an experiment in
which methane, ammonium,
hydrogen, and water were
subjected to an electrical
discharge. After a week, 10-
15% of C formed organic
compounds, 2% as amino
acids.
Suggests that a primitive
atmosphere could produce life
compounds.
Remember these?
Meteorites called carbonaceous chondrites
The juxtaposition of very high temperature components (chondrules
and inclusions made of silicates) and very low temperature components
(complex carbon compounds).
Amino acids are a long way from proteins and
nucleic acid
The next step is the subject of ongoing
investigations.
One current theory: the RNA world
RNA has the ability to copy itself, modify as an
enzyme, and bond with amino acids.
Many viruses proliferate with nothing more
than RNA and protein (although few think
viruses were the first life – too dependant on
cellular life)
Q: what’s the next step and why?
The existence of
life deep in the
ocean at
extreme
conditions has
led many to
conclude that
early life may
have used the
heat of the Earth
for energy
We are still a long way from understanding how life
chemistry came together initially.
Q: What are the two sources of external
energy on planet Earth used by life?
http://projects.edtech.sandi.net/miramesa/Organelles/fossilbact.html
Cellular life
The oldest fossils – not
much to look at, but
appears to be a filamentous
bacteria from 3.5 billion
years ago.
It’s life, as we know it
Cyanobacteria from the Bitter
Springs chert of central Australia, a
site dating to the Late Proterozoic,
about 850 million years old.
Cyanobacteria [P]
Stromatolite
Meet BIF (Banded Iron Formation)
Rock is 2.5 billion years old (found world
wide from 3 - 1.8 Ga)
Dark: Hematite (Fe2O3)
Red: Quartz (with iron)
Yellow: Crocidolite (blue asbestosform)
The accumulation of iron as seafloor
sediments is thought to result from early
photosynthesis on the ocean surface
under N2 – CO2 rich conditions.
A lack of atmospheric O2 permits Fe ions
in surface seawater – these bond with O2
produced by photosynthesis.
Big changes on Earth
24-507Figure 24.4
Scientists think
that the first
organisms
(producers)
depleted an
initially CO2 rich
atmosphere,
enriching it in
oxygen
Q: what process
may have
enriched O2 in the
atmosphere?
The endosymbiotic theory
24-506Figure 24.3
Earliest life is prokaryotic
Double-walled membrane
of organelles associated
with energy,
mitochondria and
chloroplasts, indicate
that these eukaryotic
organelles may have
been separate
prokaryotes that were
incorporated into the cell
structure.
Q: what is the
endosymbiotic theory?
Eukaryotes can be single cellular or multicellular. Specialized
cells developed. Some cells in complex organisms can be
quite complicated.
Recall that sponges (poriphera) are examples of animals
Note, sponges, are extensive in the fossil
record, beginning 540 Ma – a hard skeleton
made of calcite or quartz makes them incredibly
durable.
Specialized cells
apparently arose by 650
Ma, with the Vendian
organisms. They look
like casts of soft parts –
but not much is known
about these critters.
Fungi also arise at the same
time. Fungi can be
monocellular, colonial, or
multicellular.
The one in the picture (right) is
only 360 Ma from the Rhynie
Chert, Scotland.
Starting at 570 and leading to 540 million years ago, life
diversified. The number of fossils increases in the rocks, and
they organisms have different morphologies. Many of these
organisms have some relatives alive today
Segmented arthropods: trilobites
Sponges
Bryozoa
Corals
Brachiopods
The reason is the source of serious scientific debate, but
obviously linked to emerging (and possibly stabilized) thermal
and chemical conditions in the ocean.
Recall that plants are very close to algae in
genetic structure
Algae are another organism that has its oldest
fossils in the Cambrian.
Plants occur much higher in the record – 440
million years ago, and are found in rocks that
formed on land.
Plants are simple to complex multicellular
autotrophs. Key is the development of
specialized cells to extract moisture, amino
acids, nitrates, phophates, and minerals from
soils (roots).
Some of the earliest fossils are fern-like in
morphology
Note: modern land plant height is limited by
gravitational constraints of lifting water.
Animals are heterotrophs – they need to eat
autotrophs to get carbohydrates.
Until recently, fossil land animals were found
to be all younger than fossil plants
However, a 470 Ma fossil of a millipede,
discovered in 2004, is now thought to be the
oldest land fossil. Either older land
autotrophs existed or this millipede stayed
close to the water.
The conversion from water to land (or vice versa) is a difficult one
Most (but not all) aquatic heterotrophs organisms extract oxygen
from water*, and autotrophs carbon dioxide from water. Most land
heterotrphs extract oxygen from air.
Life is largely made of water, and therefore is similar in density. Most
organisms are boyant in water (and not in air). Gravity is more of a
factor on dry land.
*the attempt to extract oxygen from water in organisms that extract it from air is the
phenomena known as drowning.
The fossil record not only tells of the development of life, it speaks to
the termination of organisms.
Extinction is when a type of organism (species) fails to appear past a
certain time horizon in the fossil record, or ceases to exist in modern
ecosystems.
Extinctions happen throughout time, but there have been six to seven
points in earth history when a significant number of organism types
became extinct.
650, 540, 510, 440, 340, 248, 65 million years
The cause of mass extinctions is not known, but most theories point
to global catastrophe
Bolide impacts (likely for the K-T)
Large-scale volcanism
Rapid climate change
Slow magnetic reversals
The end of the world occurred 248 million years ago -
the Permian extinction
Ninety to ninety-five percent of marine species were eliminated as
a result of this Permian event.
Gone:•fusulinid foraminifera
•trilobites
•rugose and tabulate corals
•blastoids
Reduced•bryozoans
•brachiopods
•ammonoids
•Sharks
•bony fish
•eurypterids
•echinoderms
Why
This was a long time ago - some ideas•Global cooling/sea level drop
•Pangea formation
•Glaciation - global dehydration
•Intense volcanism
In contrast, the Cretaceous extinction was a mild event
Sixty percent of all species were eliminated as a result of this
Permian event.
Clay layers from this
boundary typically
include enriched iridium.
The prevailing theory for this
extinction involves bolide
impact at the Yucatan
Peninsula - the Chicxalub
structure.
Geologic Time Scale
20-424Figure 20.50
Oldest humanoid fossil 4.3 Ma
Oldest fossil plants 440 Ma
Oldest chordates 510 Ma
Oldest fossil green algea 530 Ma
Oldest shelled invertebrates 570 Ma
Oldest animal fossils (Vendian)
Oldest fossil fungi 650 Ma
Oxygenated atmosphere 1.7 Ga
Oldest fossil organism 3.5 Ga
Oldest rock 3.9 Ga
Q: what is the significance of plants
with respect to environment?
By the early 1800’s, it became clear that the Earth had a long
history preserved in the rocks.
Many of these organisms exhibited small changes in
morphology with time
The complexity of life increased with time
People started to wonder how this diversity could arise
through natural processes.
Lamarck theoryJean Baptiste Pierre Antoine de Monet, Chevalier de Lamarck
24-513aFigure 24.16a
Lamarck advocated that organisms could adapt within a
generation. Traits developed as adaptations to the
environment. These are passed to offspring (in a sense, he
was right about bacteria)
Darwin-Wallace
TheoryCharles Darwin
Alfred Russel Wallace
24-513bFigure 24.16b
Darwin and Wallace concluded that adaptations were
multigenerational. Organisms that could not overcome
changes in requirements died out, removing their hereditary
traits from a population
Darwin-Wallace evolution has been summarized as
“survival of the fittest.” Organisms that can’t adapt, die,
and in most cases won’t reproduce.
True story: In the early 1930’s, the Soviet Union
developed an agricultural process under T.D. Lysenko
based on Lamarkian evolution, purportedly because
Darwinian evolution was contrary to Stalinist ideals.
Lysenko claimed that winter wheat would adapt into
spring wheat if planted later in the year. (He also later
claimed that wheat would transform into barley or rye
given the right conditions). The results were
devastating.
Q: What is the difference between
Lamark and Darwin-Wallace theories?
Example of selection
24-509Figure 24.9
Short clovers are selected on the side of the fence with
the cows, because the long phenotype is removed.
Selection was not a
new idea in Darwin’s
time. The first chapter
of The Origin of
Species discusses
breeding and
husbandry
development of
domesticated animals.
Darwin and Wallace
saw the same
processes with the
environment choosing
the preferred features
of the offspring.
Q: how and when did a specific breed of
dog arise (a German Shepard, for example)?
All members of C. familiarus are likely descendents
of wolves in or near China 15,000 years ago.
The traditional view of natural selection means that small
changes to organisms would happen all the time. If organism
A is related to Organism B, then there should be some
intermediate organism that links the two and shows the
gradual progression.
Much of the fossil record does not show this. Many
morphological types of organisms (i.e. species) persist for
long periods of time in the fossil record. Organisms appear
and disappear quite quickly.
In the early seventies, Niles Eldredge and Stephen Gould
suggested that adaptation happens very quickly – giving rise
to organisms that are well suited for long periods of time
Punctuated equilibrium
1. Modern life constrains the ancient
2. New species split from populations
3. Most new species are in geographical isolation.
4. Large, widespread species usually change slowly, if at all.
5. Daughter species are typically geographically limited.
6. Daughter species limited in time
7. The fossil record largely static with few rapid changes.
8. Adaptive change in lineages occurs with speciation.
9. Trends in adaptation occur mostly through species selection.
Punctuated Equilibrium
Q: How does punk eek differ from the more
traditional, gradual view of evolution?
24-511Figure 24.14
How new species originate
Most new
species arise
from a single
species that
becomes
geographically
divided.
Q: in what ways
would plate
tectonics
influence
evolution?
Morphology
DNA deviations
Repetition
Successful changes
Perhaps evolution is best
attempt of organisms to find
lowest energy form over time
(like any chemical phase)?
Ancestors of humans
24-514Figure 24.17
Q: how old is mankind’s direct
ancestors? Where did humanoids first
develop?
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