Chapter 5 and 6
Evolution of Living Things &
History of Life on Earth
Sections 1-3 Pages 106-129
Sections 1-3 Pages 136-153
Differences among Organisms
• Adaptation: A characteristic
that helps an organism
survive and reproduce in its
environment. Adaptations
may be physical behaviors.
• Species: A group of
organism that can mate
with one another to
produce fertile offspring.
Groups of individuals of the
same species living in the
same place make up a
population.
Do species change over time?
• Evolution: The process in which inherited
characteristics within a population change over
generations such that new species sometimes arise
Evidence of Changes over Time
• Fossils: remains or
imprints of once living
organisms
– Usually formed from
complete organisms,
parts of organisms, or a
set of foot prints
• Fossil Record: organizes
fossils by their
estimated ages and
physical similarities
Earth’s History as a Clock
Change over Time:
Evidence of Ancestry
• Drawing Connections
Scientists examine the
fossil record to figure
out the relationships
between extinct and
living organisms
Examining Organisms
• Evidence of whale
evolution: using fossils
to support the
hypothesis
Comparing Organisms
• Comparing skeletal structure: similar bones can be
examined in different animals to demonstrate a common
ancestor
• Comparing DNA: If species that have similar traits evolved
from a common ancestor , the species would have similar
genetic code
How Does Evolution Happen?
• Charles Darwin: During
a 5 year voyage, this 21
year old, traveled post
college to study nature.
• On his journey aboard
the Beagle, Darwin
collected plant and
animal samples. He
visited the Galapagos
Islands.
Darwin’s Finches
• Noticed the similarities
between plants and
animals on Galapagos
and Ecuador (600 miles
apart).
Darwin's Thinking
• Traits: a genetically
determined
characteristic
• Selective Breeding: The
human practice of
breeding animals or
plants that have certain
desired characteristics
Ideas about Population
• Darwin gained
knowledge from
Thomas Malthus’ book
An Essay on the
Principle of Population.
• Darwin reasoned that
the offspring of
survivors inherit traits
that help the offspring
survive in their
environment.
Ideas about Earth
• Darwin began to think
species could evolve
over time.
• Darwin learned from
Principles of Geology
(Charles Lyell) that
Earth had been formed
by natural processes
over a long period of
time.
Darwin’s Theory of Natural Selection
• Darwin struggled for over
20 years with his ideas
until Wallace mailed him
a letter expressing similar
ideas
• In 1859 Darwin published
Origin of the Species by
Means of Natural
Selection in which he
proposed the theory of
evolution happens
through a process that he
called natural selection
Genetics and Evolution
• Darwin lacked evidence for
parts of his theory
• He could not prove how
variation occurred
• Scientists today found that
variation happens as a result
of differences of genes
• These changes occur
whenever offspring are
produced
• These changes allow the
organism better ability to
survive and reproduce, this is
called selection
Changes in Population
• Adaptation to Hunting:
example tusk less
elephants
• Insecticide Resistance:
insects can develop quick
resistance because of
their rapid reproduction
of offspring, having a
shorter generation time
• Competition for Mates:
example bird species
Forming a New Species – Speciation
• Separation: usually begin
when part of the population
gets separated from the rest
(mountain range, canyon,
lake formation)
• Adaptation: over
generation the separated
group develops new traits
• Division: If the two groups
are reunited (barrier
removed) they are no
longer the same species and
can not reproduce with
each other
Fossilized Organisms
• A fossil is the remains or
physical evidence of an
organism preserved by
geological processes
• Fossils in rock: sometimes
decaying organisms get quickly
buried by sediment (rock),
then the sediment becomes a
rock. The harder parts of the
animal (bones) become well
preserved in this newly
formed rock.
• Fossils in amber: Organisms
(insects) get caught in soft
sticky tree sap which hardens
and preserves them.
Absolute Dating
• The process of
establishing the age of
an object by
determining the
number of years it has
existed is called
absolute dating.
Radiometric Dating
•
•
•
•
If you know the rate of decay for a
radioactive element, you can determine the
absolute age of the rock.
Based on a parent to daughter ratio, you can
determine the absolute age, this process is
called radiometric dating.
A half life is the time that it takes one half of
the radioactive sample to decay.
After every half-life, the amount of parent
material decreases by one-half.
½, ¼, 1/8, 1/16
Try this example: Carbon 14’s half-life is 5, 730
years. How old will the object containing this be
when ¼, 1/8, 1/16, 1/32 of it’s Carbon 14
remains.
Geological Column
• Used to help geologists,
they combine data from
all the known
undisturbed rock
sequences around the
world
• Geologists use the
geological column to
interpret rock sequences
and to identify layers in
puzzling rock sequences
Extinction
• The death of every
member of the species.
• Can be caused by global
change and/or change
in ocean currents
Changing Earth
• Pangaea: “All Earth”
one supercontinent
breaking up
• Plate Tectonics:
Continents/huge pieces
of land moved slowly on
plates
• Adaptation to slow
change: organisms from
the past present along
with current organisms
Precambrian Time
• Time from the formation
of the Earth, 4.6 billion
years ago to about 543
million years ago.
• Violent events (volcanic
eruptions) and harsh
atmosphere.
• Simple chemicals may
have reacted during these
storms from the energy of
radiation. Single celled
organisms resulted
(prokaryotes).
Precambrian Time
• Photosynthesis and OxygenCyanobacteria used sunlight
to make food over 3 billion
years ago, and started to
release Oxygen. Ozone layer
began to form as a result.
• Multi cellular Organisms-A
billion years after
prokaryotes appeared Earth
had eukaryotes (many
celled organisms with a
nucleus)
Paleozoic Era
•
•
•
•
•
Marine life flourished
Land plants appeared
Amphibians and reptiles
Insects
Largest mass extinction
in Earth’s
history….cause? Ocean
currents?
Mesozoic Era
•
•
•
•
Age of the Reptiles
Small mammals
Dinosaurs and birds
Extinction….cause?....
Global climate?
Cenozoic Era
• Age of Mammals
• Mammals competed
with dinosaurs
• Due to climate
change…mammals
better suited for
environment
Humans and other Primates
• Primates – group of
mammals that include
humans, apes, monkeys,
and lemurs (opposable
thumbs and binocular
vision)
• Hominids- includes
humans and other human
like ancestors. The main
difference is bipedalism
“walking upright”
Hominids through Time
• Early Hominids- similar to
humans more than apes.
Oldest fossils in Africa- 6 to
7 millions years old.
• Australopithecines- Similar
to apes, found in Africa. Had
human like and ape like
characteristics
• Global Hominids- Slender,
more human like, larger and
more complex brain, walked
upright and used tools.
(homo habilis and homo
erectus)
Recent Hominids
• Neanderthals- about
400,000 years ago,
extinction, reason
unknown
• Early and Modern
Humans- homo sapiens,
first to create art
• Paleontologists will
review their ideas about
evolution of hominids
Comparison of Hominids
Australopithecines
Early Homo
Homo sapiens
Bipedalism
yes
yes
yes
Brains
medium
larger
largest
Tools
none
some
many
Art
none
none
A lot
Known Locations
Africa
Several continents
World wide
Brain Pops, Games, etc.
• Darwin
• Natural Selection
• Primates
• Human Evolution
• http://exploringorigins.org/index.html
GAMES!!!
• http://science.discovery.com/interactives/literacy/darwin/
darwin.html
• http://www.pbs.org/wgbh/nova/evolution/evolutionaction.html
• http://www.mnh.si.edu/ete/ETE_Education&Outreach_Ga
me.html