Life’s
Record
Early Earth
• Early earth was most
•
likely very hot with lots of
lava flow. Only Archea
bacteria would have been
able to survive in the
early earth conditions.
Gases coming from
violent eruptions helped
create earth’s
atmosphere, such as
water vapor, carbon
dioxide, and nitrogen.
Fossils
• Evidence of an organism
•
that lived in the past.
Types
 Trace fossils
 Casts
 Imprints
 Petrified
 Molds
 Amber preserved and
frozen fossils.
http://biology.stand.ac.uk/sites/bellpet/fossils.jpg
Fossilization Process
• Animal dies
• Gets covered by dirt/
•
•
•
sediments.
Over time, layers and
layers build up on
remains.
Earth movements reveal
remains, and they are
found.
Pg.381 of text
Who are Paleontologists?
• Scientists who study fossils.
• By studying fossils, these scientists gain
insight into what the past was like, what
creatures lived at different times, and by
doing this they construct the
Geologic Time Scale.
Dating Fossils
• Relative Dating
– Fossils at the top of layers of earth are younger than those at
the bottom.
– This is a geological law
– Can’t be used to tell specific age of fossil
• Radiometric Dating
– Done by using the decay rate of radioactive isotopes, the Half
Life [the time it takes for half of the material to decay]
– Most common used are:
• Potassium 40, half life=1.3 billion yrs [older fossils}
• Carbon 14, Half Life=5730 yrs [fossils less than 50,000 yrs old]
How did life begin: Early Ideas
• Spontaneous Generation
– Idea that nonliving material
could form life.
– Redi’s and Pastuer’s
experiments disproved this
idea.
• Redi experimented with
•
flies, maggots, and meat.
Pastuer experimented with
broth.
http://biology.clc.uc.edu/graphics/bio104/redi.jpg
• Biogenesis
– Living organisms can come
only from other living
organisms
http://www.slic2.wsu.edu:82/hurlbert/micro101/imag
es/hist9.gif
Evolution of Life
• Two developments that preceded appearance of
life on Earth:
– Simple organic molecules form
– These molecules organized into complex organic
molecules (proteins, carbs, nucleic acids)
• Protocells then formed
– Large, ordered structures enclosed in a membrane. It
carried out some basic life functions such as growth
and division.
Evolution of cell
http://images.google.com/imgr
es?imgurl=www.siu.edu/~prot
ocell/photos/siu1.gif&imgrefurl
=http://www.siu.edu/~protoce
ll/photos2.htm&h=605&w=482
&prev=/images%3Fq%3Dprot
ocell%26svnum%3D10%26hl
%3Den%26lr%3D%26ie%3DU
TF-8%26oe%3DUTF-8
• First true cells
– Possibly prokaryotes that evolved from
protocells.
– Were probably heterotrophs (feeding off of
other things, such as organic molecules)
• Autotrophs evolved (photosynthesis
begins), thus increasing concentration of
O2 in atmosphere.
Endosymbiont Theory
• Proposed by Lynn Margulis in 1960’s
• Proposes that:
– Eukaryotes evolved through a symbiotic relationship
with prokaryotes (sharing)
– Anerobic bacteria was engulfed (phagocytosis) and
became chloroplasts.
– Evidence for this is:
• Both chloroplasts and mitochondria contain their own DNA
that is similar to that of prokaryotes
• Size of these organelles is equivalent or similar to that of
prokaryotes
• That these organelles are membrane bound
http://www.mrs.umn.edu/~goochv/CellBio/lectures/endo/Image157.gif
The Theory of
Evolution
What is EVOLUTION anyway?
• Evolution is
change in a
population over
time.
• The word itself
refers to
CHANGE.
Charles Darwin
• Proposed the theory of
•
evolution by natural selection.
He came up with this theory
through studying nature
during his voyage on the HMS
Beagle.
• During this voyage he explored
http://academy.d20.co.edu/kadets/lun
dberg/darwin/darwin.JPG
life on the Galapagos Islands.
• He studied the large tortoises
that are found there.
• Natural selection was
proposed to explain how
species changed over time.
http://www.victory-cruises.com/graphics/BEAGLE.gif
Darwin’s Experiments
• He bred pigeons and studied traits the
population inherited.
• By doing this he was using artificial
selection (breeding for specific
traits).
• He studied the traits that were
passed down from the parent
generation and looked at how
they adapted to specific selective
forces (things that cause
adaptation).
How does Natural Selection work?
• Different things happen to the
environment that cause species to be
forced to adapt. The ones that survive
reproduce and pass on the selected
for traits.
• These traits enable the offspring to
survive until the environment changes
and forces new traits to be selected
for.
Adaptations: Take Time!!
• Adaptations are evidence for evolution.
But these adaptations take time, and
normally take a few generations.
• There are two different adaptations
– Structural
– Physiological
Structural Adaptations
• Common examples are teeth size,
http://www.msmedia.com.a
claw size, ect…
• More specifically
– Mimicry, this structural adaptation
enables one animal to look like
another. This may be used to
resemble a dangerous animal for
protection, or used by predators
to capture prey.
– Camouflage, enables animals tohttp://
blend in with their surroundings,
helps in avoiding predators.
u/Science/images/mimicry.jpg
students.washington.edu/co
chranb/hawaii/camouflage.jpg
Physiological Adaptations
• These changes occur in the
organism’s metabolism.
• One example is the quick
adaptations of bacteria to the
lethal affect of penicillin, in •
other words they are
becoming immune, requiring
higher and higher doses to kill
bacteria.
• Another example is increased
pesticide resistance in plants
and insects.
http://forum1.sewanee.edu/palisano/wastewat
er/images/ecoli.jpg
Other Evolution
Evidence
• Fossil record show signs of evolution
• Anatomy of organisms
– Homologous structures, structures similar in
arrangement, function, or both. This is evidence of
evolution from a common ancestor.
– Analogous structures, body structures that do not
have a common origin, but that are similar in function.
– Vestigial structure, a body structure that has no
function, it is thought to be retained from evolutionary
ancestor through heredity.
Evidence continued
• Embryology
– This deals with the similarities in
embryos (the first stage of life) of
different species.
• Biochemistry
– This uses the comparisons of DNA
or RNA of different species to
show evolutionary relationship.
http://www.cord.edu/faculty/landa/courses/
b315f99/sessions/phylogeny/embryology.jpg
Primate Evolution
What are Primates?
• They are a group of
•
•
mammals.
This group includes
lemurs, monkeys, apes,
and humans.
They come in all
different shapes and
sizes.
Common Characteristics of
Primates
• They all have opposable thumbs.
• Their brain volume is large compared to
their body size.
• Vision is the dominant sense, binocular
vision.
• Arms adapted for a great range of motion.
• Flexible joints
• Feet are able to grasp things.
How did they evolve?
• Scientist use fossils,
comparative anatomical
features (body similarities), and
DNA to propose evolution
ideas.
• Prosimians evolved first.
– These were small present day
primates such as lemurs.
Anthropoids Evolve...
• Anthropoids are
humanlike primates.
• They evolved after the
prosimians.
• They includes apes
and humans.
http://www.mosartdesigns.on.ca/largeart/paintings-ape.jpg
Differences of Anthropoids
• They have more complex brains than
prosimians.
• Larger and different skeletal features
(more upright posture)
• Examples are Gibbons, orangutans,
chimpanzees, and gorillas.
Old World and New World
Monkeys
• These are two classes monkeys are
broken up into.
• Old world are generally larger, and may
be terrestrial.
• New World live in South and Central
America.
• They are all Arboreal (living in the trees)
and have long, muscular prehensile tail.
Humans tied in
• Scientist theorize
•
http://www.bio.psu.edu/faculty/hedges/primate.gif
that we were the
last to evolve.
We have an even
larger brain capacity
and walk upright.
Hominoid Evolution
• Hominoids or humans began to evolve in
Asia and Africa as the fossil records shows
us.
• Hominoids include apes and humans.
• Scientists think that gibbons were the first
to evolve, then orangutans, followed by
the African apes, chimpanzees, and
gorillas. One of these being or possible
ancestor.
Human Ancestry
http://www.centerfortheperson.org
/HUMAN%20EVOLUTION.jpg
• Scientist believe that there were two lines
•
evolving. One being humans, and the other
were the African apes- gorillas and
chimpanzees.
Bipedal adaptation of humans sets us apart.
(walking upright)
Time line of evolution
Homo sapiens
Homo erectus
Homo habilis
A. boiseri
A. robustus
Australopithecus africanus
Australopithecus afarensis
Development of culture
• The first known humanoid
•
http://cator.hsc.edu/~kmd/caveman/shanidar.jpg
•
fossils was
australopithecine.
Next came the Neanderthals
who lived in Europe, Asia,
and the middle East 35000100000 yrs ago.
Cro-Magnons then became
the most recent modern
human ancestor.
Neanderthals & Cro-Magnons
• Neanderthals were the first humanoids to
use tools for hunting and to use fire.
• Through them a semblance of culture
developed.
• Cro-Magnons further developed the use of
language and art, primarily cave drawings.
They also advanced tool making.