Evolution – Life Through

Time

J. D. Price

Natural Science II – ERTH 1040

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.

Solar System Formation

4.6 billion years ago

Q: From what materials is our solar system made?

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).

24-515Figure 24.24

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

Archaea [D] (extremophiles)

Q: the oldest life belongs to what Kingdom?

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.

Earth!

million years without a single mass extinction6 5

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?

Humans are

relative new

comers to life

on this planet.

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?

Gradualism

Punk Eek

Q: what’s the

difference?

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?

Spencer Wells

the y-chromosome is a

parcel of DNA, passed

on from father to son,

basically unchanged

for generations save

random mutations.

By looking at modern individuals y-chromosome

DNA, a migration path for H. sapiens is revealed.

Q: What would have prompted this migration at 50,000 years?