History of Life and Evolution
Transcript History of Life and Evolution
• 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
atmosphere, such as
water vapor, carbon
dioxide, and nitrogen.
• Evidence of an organism
that lived in the past.
Amber preserved and
• Animal dies
• Gets covered by dirt/
Over time, layers and
layers build up on
Earth movements reveal
remains, and they are
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.
• Relative Dating
– Fossils at the top of layers of earth are younger than those at
– 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
• Redi experimented with
flies, maggots, and meat.
Pastuer experimented with
– Living organisms can come
only from other living
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
Evolution of cell
• First true cells
– Possibly prokaryotes that evolved from
– Were probably heterotrophs (feeding off of
other things, such as organic molecules)
• Autotrophs evolved (photosynthesis
begins), thus increasing concentration of
O2 in atmosphere.
• Proposed by Lynn Margulis in 1960’s
• Proposes that:
– Eukaryotes evolved through a symbiotic relationship
with prokaryotes (sharing)
– Anerobic bacteria was engulfed (phagocytosis) and
– 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
• That these organelles are membrane bound
The Theory of
What is EVOLUTION anyway?
• Evolution is
change in a
• The word itself
• Proposed the theory of
evolution by natural selection.
He came up with this theory
through studying nature
during his voyage on the HMS
• During this voyage he explored
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.
• He bred pigeons and studied traits the
• By doing this he was using artificial
selection (breeding for specific
• 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
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
• These traits enable the offspring to
survive until the environment changes
and forces new traits to be selected
Adaptations: Take Time!!
• Adaptations are evidence for evolution.
But these adaptations take time, and
normally take a few generations.
• There are two different adaptations
• Common examples are teeth size,
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.
• These changes occur in the
• 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
• Another example is increased
pesticide resistance in plants
• 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.
– This deals with the similarities in
embryos (the first stage of life) of
– This uses the comparisons of DNA
or RNA of different species to
show evolutionary relationship.
What are Primates?
• They are a group of
This group includes
lemurs, monkeys, apes,
They come in all
different shapes and
Common Characteristics of
• They all have opposable thumbs.
• Their brain volume is large compared to
their body size.
• Vision is the dominant sense, binocular
• Arms adapted for a great range of motion.
• Flexible joints
• Feet are able to grasp things.
How did they evolve?
• Scientist use fossils,
features (body similarities), and
DNA to propose evolution
• Prosimians evolved first.
– These were small present day
primates such as lemurs.
• Anthropoids are
• They evolved after the
• They includes apes
Differences of Anthropoids
• They have more complex brains than
• Larger and different skeletal features
(more upright posture)
• Examples are Gibbons, orangutans,
chimpanzees, and gorillas.
Old World and New World
• These are two classes monkeys are
broken up into.
• Old world are generally larger, and may
• New World live in South and Central
• They are all Arboreal (living in the trees)
and have long, muscular prehensile tail.
Humans tied in
• Scientist theorize
that we were the
last to evolve.
We have an even
larger brain capacity
and walk upright.
• Hominoids or humans began to evolve in
Asia and Africa as the fossil records shows
• 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
• Scientist believe that there were two lines
evolving. One being humans, and the other
were the African apes- gorillas and
Bipedal adaptation of humans sets us apart.
Time line of evolution
Development of culture
• The first known humanoid
Next came the Neanderthals
who lived in Europe, Asia,
and the middle East 35000100000 yrs ago.
Cro-Magnons then became
the most recent modern
Neanderthals & Cro-Magnons
• Neanderthals were the first humanoids to
use tools for hunting and to use fire.
• Through them a semblance of culture
• Cro-Magnons further developed the use of
language and art, primarily cave drawings.
They also advanced tool making.