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EVOLUTION
• EARTH IS THOUGHT TO BE 4.6 BILLION YEARS
OLD WITH THE FIRST LIVING ORGANISMS APPEARING
3.5 BILLION YEARS AGO
• MAN APPEARED ON EARTH ABOUT 2 MILLION YEARS AGO.
(H. HABILIS)
(HOMO SAPIEN = 100,000 YEARS AGO)
HOW DID LIFE BEGIN?
• EVOLUTION – CHANGE OVER TIME; IMPLIES THAT
LIFE BEGAN AS A SINGLE CELL AND THAT
ORGANISMS CHANGED OVER TIME
HOW DID LIFE BEGIN?
• CREATIONISM – GOD CREATED WORLD AND
EVERYTHING IN IT IN 6 DAYS; IMPLIES THAT THE
ORGANISMS PRESENT TODAY ARE THE SAME
ONES GOD PUT ON EARTH
HOW DID LIFE BEGIN?
• INTELLIGENT DESIGN – STATES THAT FEATURES OF
ORGANISMS ARE BEST EXPLAINED BY AN
INTELLIGENT DESIGN RATHER THAN AN UNDIRECTED
MECHANISM
GEOLOGICAL TIMELINE
• SHOWS WHEN DIFFERENT LIFE FORMS ORIGINATED
DUE TO EVOLUTION
PROOF FOR EVOLUTION
1. FOSSIL – ANY PART OF A LIVING OR ONCE LIVING
ORGANISM; ENTIRE ORGANISM, BONES OF AN
ORGANISM OR AN IMPRESSION IN A ROCK
A. EXTINCT – WHEN ALL ORGANISMS OF A SPECIES
ARE NO LONGER LIVING
PROOF FOR EVOLUTION
2.
COMPARATIVE ANATOMY – STUDY OF THE
STRUCTURES OF ORGANISMS; LEGS OF DOGS, PIGS,
SHEEP, AND HORSES ARE SIMILAR
PROOF FOR EVOLUTION
3.
COMPARATIVE EMBRYOLOGY – STUDY OF THE
EMBRYOS; EMBRYOS OF CHICKEN, TURTLE, AND RAT
ARE SIMILAR
PROOF FOR EVOLUTION
4.
COMPARATIVE BIOCHEMISTRY – STUDY OF THE
CHEMICALS OF LIFE; BLOOD OF HUMANS AND
CHIMPANZEES ARE SIMILAR
LAMARCK AND DARWIN
1. LAMARCK - SUPPORTED THE IDEA OF EVOLUTION
a.
LAW OF USE AND DISUSE; ORGANISMS COULD CHANGE BODY
FEATURES DURING LIFE TIME I.E. GIRAFFE
CHANGE CALLED ACQUIRED CHARACTERISTICS
b.
INHERITANCE OF ACQUIRED CHARACTERISTICS – ACQUIRED
CHARACTERISTICS ARE PASSED ONTO OFFSPRING
* THIS IS NOT ACCEPTED BECAUSE GENETIC INFORMATION CAN ONLY BE
PASSED ON TO THEIR OFFSPRING THROUGH SEX CELLS, NOT BODY
CELLS
DARWIN
VOYAGE OF THE BEAGLE:
DARWIN’S OBSERVATIONS:
DARWIN
a. STRUGGLE FOR EXISTENCE – BASED ON AN ESSAY
WRITTEN BY MALTHS THAT SAID THE POPULATION
WAS GROWING FASTER THAN THE FOOD SUPPLY;
PEOPLE WILL SUFFER AND DIE
b. SURVIVAL OF FITTEST – NATURAL SELECTION; DUE TO
THE STRUGGLE FOR EXISTANCE, ONLY THE BEST,
STRONGEST, FASTEST, ETC. WILL SURVIVE
DARWIN’S THEORY OF NATURAL
SELECTION
1. IN NATURE, THERE IS A TENDENCY FOR OVER REPRODUCTION.
2. NOT ALL ORGANISMS SURVIVE
3. VARIATION EXIST IN ALL POPULATIONS
4. SOME VARIATIONS ARE HELPFUL, SOME HARMFUL
5. VARIATIONS THAT ARE SUITABLE FOR THE ENVIRONMENT WILL
SURVIVE AND BE PASSED ONTO OFFSPRING, UNSUITABLE
VARIATIONS WILL BE ELIMINATED
6. POPULATIONS AS A WHOLE WILL BE BETTER FIT FOR ITS
ENVIRONMENT
THEORIES OF EVOLUTION
JEAN BAPTISTE-LAMARCK
• LIFE
• 1744-1829 (FRANCE)
• SPECIES
• THERE IS LITTLE VARIATION
• INDIVIDUALS CAN CHANGE IF
THEY NEED TO
• WHAT CAUSES CHANGE
• THE ENVIRONMENT
• DRIVE FOR PERFECTION
• THEORIES
• ACQUIRED TRAITS
• LAW OF USE AND DISUSE
CHARLES DARWIN
• LIFE
• 1809-1882 (ENGLAND)
• SPECIES
• A LOT OF VARIATION
• POPULATIONS CHANGE NOT
ORGANISMS
• WHAT CAUSES CHANGE
• THE ENVIRONMENT
• THEORIES
• STRUGGLE FOR EXISTENCE
• ADAPTATION
• NATURAL SELECTION (SURVIVAL OF
THE FITTEST)
• DESCENT (COMMON & MODIFIED)
ADAPTATION
AND SPECIATION
POPULATION
l the members of a species that live in an
ea
A POPULATION’S GENES CHANGE OVER
TIME
GENE POOL: ALL OF THE ALLELES OF THE
POPULATION’S GENES
ORGANISMS HAVE ADAPTATIONS THAT
ALLOW THEM TO BETTER SURVIVE
•Adaptation: an inherited trait which helps
organisms survive; starts with a variation. After
many generations, all of the organisms have the
variation, now called an adaptation
oMorphological: structure
oBones of hand, beaks of bird
oPhysiological: inner working of an organism
oEnzymes for digestion, clotting of blood
oBehavioral: instinctive reactions to the
environment
o migration of bird, storing of nuts by squirrels
EVOLUTION OF ADAPTATIONS
• SPECIES – GROUP OF ORGANISMS THAT BREED AND
PRODUCE FERTILE OFFSPRING
SPECIATION:
EVOLUTION OF A NEW SPECIES THAT
OCCURS WHEN MEMBERS OF SIMILAR
POPULATIONS CAN NO LONGER BREED
AND PRODUCE FERTILE OFFSPRING
BECAUSE ……….
GEOGRAPHIC ISOLATION: WHEN A PHYSICAL
BARRIER (LAVA FROM VOLCANIC ERUPTIONS,
SEA LEVEL CHANGES, ETC.) DIVIDES A
POPULATION
AND EACH NEW, SMALLER POPULATION ADAPTS
TO ITS OWN ENVIRONMENT CREATING NEW
SPECIES
REPRODUCTIVE ISOLATION: WHEN
ORGANISMS NO LONGER BREED WITH
EACH OTHER TO PRODUCE FERTILE
OFFSPRING BECAUSE……….
THE GENES BECOME TOO DIFFERENT AND
FERTILIZATION CANNOT OCCUR
MATING TIMES
CHANGE TO
DIFFERENT TIMES
OF THE YEAR
ONE POPULATION BECOMES POLYPLOID
(DOUBLE, TRIPLE, ETC. OF THE NORMAL
NUMBER OF CHROMOSOMES) BECAUSE
OF MISTAKES IN MITOSIS OR MEIOSIS, SO
THEY CAN’T BREED WITH THE OTHER
POPULATION
DIVERGENT
EVOLUTION:
SPECIES THAT ONCE
WERE SIMILAR
BECOME
INCREASINGLY
DIFFERENT CREATING
BIODIVERSITY
CONVERGENT EVOLUTION: UNRELATED
SPECIES EVOLVE SIMILAR TRAITS
BECAUSE THEY OCCUPY SIMILAR
ENVIRONMENTS
EVOLUTION AND HUMANS
THE PHYLOGENY OF LIVING SPECIES
MOST CLOSELY RELATED TO US LOOKS
LIKE THIS:
IT IS IMPORTANT TO
REMEMBER THAT:
HUMANS DID NOT EVOLVE FROM
CHIMPANZEES. HUMANS AND
CHIMPANZEES ARE EVOLUTIONARY
COUSINS AND SHARE A RECENT
COMMON ANCESTOR THAT WAS
NEITHER CHIMPANZEE NOR HUMAN.
* HUMANS ARE NOT "HIGHER" OR "MORE
EVOLVED" THAN OTHER LIVING PRIMATES.
* HUMANS ARE VERY GOOD AT BEING
HUMANS.
* CHIMPANZEES ARE VERY GOOD AT BEING
CHIMPANZEES.
* CHIMPANZEES ARE NOT LESS EVOLVED
HUMANS.
* HUMANS ARE NOT LESS EVOLVED
CHIMPANZEES.