Download Evidence for Evolution

Evidence for Evolution
Evidence
• Ever since Darwin
introduced his ideas of
natural selection,
scientists have been
looking for evidence
• There are many
different areas of
science that
contributed to the
evidence for natural
selection
Evidence
• Previous scientists have
found evidence for
natural selection in the
fields of biology,
geology, chemistry and
physics
• Modern day scientists
have found evidence for
evolution in the field of
genetics
Fossils
• A fossil is the remains
or traces of an organism
that died long ago
• Fossils most often form
when a trace of an
organism is buried
• Traces of an organism
can be a footprint,
droppings, eggs, a
corpse, etc.
Fossils
• Fossils provide us small
snapshots of the past
that can be used gain
knowledge of the past
• With the right amount
of fossils, we can build a
complete picture of the
looks, actions and
patterns of ancient
organisms
Fossils
• We can tell how old
fossils are in two ways
• Superposition is the
idea that the deeper a
rock formation is, the
older it is
• If we know that age of a
rock formation, we can
approximate the age of
the fossils in it
Fossils
• Carbon dating is a
measurement of how
old an element is
• This allows modern day
scientists to see how
old the carbon in a
particular fossil is
• It give a good
approximate of the age
of fossils
Video
• http://www.youtube.co
m/watch?v=SEDfRy6DQ
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Fossil Record
• With these fossils we
can draw conclusions
about the organisms on
the earth during
different time periods
• We can line up the
fossils and make a
timeline of what
organisms looked like
and how they changed
Fossil Record
• What we see most
often in organisms is
that they have adapted
over time
• Species do not
randomly appear
• Different species come
from different
adaptations
• http://www.youtube.co
m/watch?v=GOKW_7Ka
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Anatomy
• Anatomy is the study of
structures in the body
• Anatomy also provides
very compelling
evidence for natural
selection
• Some of the structures
of animals are very
similar
Anatomy
• Compare the two
structures that you see
here
• What is similar about
them?
• What is different about
them?
Anatomy
• The structures of both
the human hand and
the bat hand are very
similar
• The bones, the joints
and the placement of
the bones are all similar
• This goes across other
animals as well
Anatomy
• Homologous structures
are anatomical
structures that
originated by heredity
– They have a related
structure and function
• This means they are
similar because they
were passed down from
a common ancestor
Anatomy
• Analogous structures
have closely related
functions but do not
derive from similar
ancestors
• A good example of this
would be a bird and a
butterfly
• They both have wings,
but they are built nothing
alike
• This is because they came
from a different ancestor
Anatomy
• Sometimes there are
structures that are left
in organisms long after
they have ceased to be
useful
• These are remains of
structures that from
ancestors long past
• We call these vestigial
structures
Anatomy
Biogeography
• Darwin noticed
something on his
voyage that is evidence
for natural selection
• Darwin noticed that in
different parts of the
world there are
organisms that are
closely related but are
geographically far apart
Biogeography
• These organisms were at
one time the same
species
• When land masses began
moving, the species was
separated
• When the species
separated, there were
different adaptations
• This created the different
species we see today
Genetics
• With the advent of
modern technology we
can start to study
evolution and natural
selection at a genetic
level
• Modern genetics allows
us to make comparisons
in DNA to other
organisms
Genetics
• When we look at DNA
and how it is expressed
we can see the
relationships between
organisms
• It gives us a better idea
of what organisms are
closely related, even if
they don’t look like
each other
Embryo Evidence
• Think about all the ways
of producing offspring
• Are they similar or
different?
• What is an embryo?
• An embryo is an unborn
or unhatched organism
that is developing
Embryo Evidence
• The process of
development is similar
across many organisms
• Many organisms have
structures when they
develop that are not
seen in their final form
• For example humans
have tails when they
develop
Embryo Evidence
• Why would these
embryos have
structures that are not
seen in their final
forms?
• It is because they share
common ancestry
• The common ancestor
had a feature that is not
present in the current
organism
Video
• http://www.youtube.co
m/watch?v=h3Lkac890c
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