Transcript EVIDENCE OF EVOLUTION

EVOLUTION
THE EVOLUTION OF EVOLUTIONARY
THEORY
BEFORE DARWIN
• CREATIONISM = first explanation of diversity
observed = separate creation of each
organism by a supernatural being
• Scientists however historically have sought
natural causes for the origin of species
HISTORY OF EVOLTION
• HOW TO DISTINGUISH A SPECIES?
o Differences in appearance  Reproductive
isolation
o Today’s Definition of SPECIES: a population of
organisms that are capable of interbreeding
under natural conditions
GREEK PHILOSOPHERS
• PLATO – “Ideal Form” = object
on earth were created by God
in their ideal form and do not
change, although minor
variations do occur due to the
imperfections of our world
• ARISTOTLE – “Scala Naturae” =
ladder for classifying and
naming nature in which each
species had a place that had
been given to it by God
EVOLUTION BEFORE
DARWIN & WALLACE
• BEFORE 1700’S – Creationism was
unchallenged
• LEAVING EUROPE- observed a greater
diversity and variety within species and
started to think about the possibility that
species could change over time
• DISCOVERY OF FOSSILS – William Smith
discovered that fossils in lower rock were
more primitive and changed to more
advanced forms as well as some fossils of
extinct forms
EVOLUTION BEFORE
DARWIN & WALLACE
• BUFFON – original creation of a few
species that evolved over time
producing the modern species
• CATASTROPHISM – catastrophes
produced layer of rock and made
species extinct and after each
catastrophe, new species were created
• UNIFORMITARIANISM – the same forces
(wind, water , volcanoes) that change
geology also produced the rock layers
and the ever changing earth
LAMARCK
• Organisms evolved through the INHERITANCE
OF ACQUIRED CARACTERISTICS
• IE. Giraffe stretch to reach trees, therefore pass
on longer necks to offspring
• Not scientifically supported
DARWIN & WALLACE
• Independently, both provided evidence that the
diving force behind evolution is natural selection
EVIDENCE OF
EVOLUTION
P. 283-285
• When scientists speak of evolution as a theory they do not
mean that it is a mere speculation. It is a theory in the same
sense as the propositions that the earth is round rather than
flat or that our bodies are made of atoms are theories. Most
people would consider such fundamental theories to be
sufficiently tested by empirical evidence to conclude that
they are indeed facts. As a result of the massive amount of
evidence for evolution accumulated over the last two
centuries, we can safely conclude that evolution has
occurred and continues to occur. All life forms, including
people, evolved from earlier species. Furthermore, all still
living species of organisms continue to evolve today. We
now understand that there are a number of different natural
processes that can cause evolution to occur. These are
presented in later lessons.
FOSSILS
• progressive series of fossils leading from an
ancient, primitive organism to a modern form
• even though the fossil record is not complete
we can form a picture from the fossils we do
have. Some animals are better represented
than others - like the horse
COMPARATIVE
ANATOMY
• Evolution predicts that organisms that evolve in
similar environments will develop similar
structures (even if these organisms are not
related) - basically that natural selection will
drive species to develop structures best suited for
the environment
COMPARATIVE
ANATOMY
• Convergent Evolution - where two unrelated
species have similar forms (a whale and a shark)
• Analogous structures - the outwardly similar
structures, like the wings of a fly and the wings
of birds
SIMILARITIES IN EARLY
DEVELOPMENT
• Embryos of many different animals look similar
• this shows that similar genes are at work
SIMIALR BODY
STRUCTURES
• HOMOLOGOUS
STRUCTURES - have
similar underlying
makeup, though
different functions. The
similarity is due to
having derived from
the same common
ancestor. Ex. the
forelimbs of various
mammals
STRUCTURES
• Structures that have no apparent purpose, like
the pelvic bones of whales, the appendix in
humans
BIOCHEMICAL & GENETIC ANALYSIS
• Similarities between organism's DNA and protein
structures show relationships. Gene sequencing
can help us determine what organisms are more
closely related than others.
ARTIFICIAL SELECTION EVOLUTION CAN BE OBSERVED!
• Artificial selection is the process
of breeding domestic plants and
animals to produce specific
desirable features in a
population.
• All dog breeds have been created
via artificial selection
• Cows have been breed over the
years to produce more milk and
become larger
RIGHT BEFORE OUR
EYES
• Natural Selection can also be observed today!
 peppered moths
 insects become resistant to pesticides
 bacteria become resistant to antibiotics
PEPPERED MOTHS
• Peppered moths in Britain
showed a shift in coloration
after the industrial revolution.
Moths were generally light
colored to match the
background of lichens on
trees. Soot from factories
turned the bark of trees to a
darker coloration, darker
colored moths increased in
number because they were
better camouflaged on the
dark trees.
ADDITIONAL NOTES
• The variations upon which natural selection works
are produced by chance mutations
• Natural selection does not produce increasing
degrees of perfection, it produces organisms best
suited for a particular environment.
• It is a common misconception the evolution will
produce better and better organisms - its simply
not true. A seal is adapted for water, but its not a
good design for a prairie. When an environment
changes, many populations can go extinct
because they are no longer suited to an
environment (dinosaurs)
MONKEYING AROUND
• It is also a common misconception that if
humans evolved from earlier primates, then we
shouldn't have monkeys at all (since they
would have all evolved to humans) - again this
is erroneous, monkeys aren't "driven" to
become humans, as long as their suited for
their environment, the process of natural
selection won't facilitate any major changes,
there are a variety of primates, just like there
is a variety of cats - but more on human
evolution later.