Transcript Evidence of Evolution

What Did Darwin Explain in his
Book, On the Origin of Species?
• He explained his theory of
Evolution by Natural
Selection
• He presented evidence
that living species evolved
from organisms that lived
in the past
– The evidence comes from
multiple fields of science
The Fossil
Record
• Fossils are traces of
organisms that lived in
the past
• Can tell relative age of organisms (which came first)
• One can compare fossils of extinct organisms to
living organisms to reveal patterns of gradual change
• Darwin noticed many “gaps”, but many new fossils
have been found that fill some of these gaps.
• Conditions that create fossils are rare so we will
never find fossils of every species that ever lived
Biogeography
• The study of the locations of organisms
around the world
• Suggests that similar environments shape
the evolution of organisms in similar ways
Embryology
• The study of the
development of
embryos
• One can compare the
embryonic stages of
different organisms to
look for similar patterns
and structures
• Similarities most likely
derive from an ancestor
that the species have in
common
Anatomy
• Scientists can compare the bodily structure of different
species to find clues about how they are related
• Many internal similarities are best explained by
evolution
• Homologous structures
are characteristics that
are similar in two or more
species and that have
been inherited from a
common ancestor
• They don’t necessarily
function similarly
Anatomy
• Vestigial Structures
– A structure or organ is vestigial if it has
diminished in size or usefulness in the course of
evolution
– Vestigial structures are markers of evolutionary
descent. For example, boa constrictors, which
are descended from four-legged reptiles, grow
tiny hind legs.
Top 10 Useless Limbs (and
Other Vestigial Organs)
• 10 - The wings on flightless birds
Top 10 Useless Limbs (and
Other Vestigial Organs)
• 9 - Hind leg bones on whales
Top 10 Useless Limbs (and
Other Vestigial Organs)
• 8 - Erector Pili and Body Hair on Humans
Top 10 Useless Limbs (and
Other Vestigial Organs)
• 7 - The Human Tailbone (Coccyx)
Top 10 Useless Limbs (and
Other Vestigial Organs)
• 6 – Eyes of blind fish
Top 10 Useless Limbs (and
Other Vestigial Organs)
• 5 – Wisdom teeth in humans
Top 10 Useless Limbs (and
Other Vestigial Organs)
• 4 – The Sexual Organs of Dandelions
Top 10 Useless Limbs (and
Other Vestigial Organs)
• 3 – Fake Sex in Virgin Whiptail Lizards
(Vestigial Behavior)
Top 10 Useless Limbs (and
Other Vestigial Organs)
• 2 – Male breast tissue and nipples
Top 10 Useless Limbs (and
Other Vestigial Organs)
• 1 – The Human Appendix
Biochemistry
• A comparison of DNA sequences shows
that some species are more genetically
similar than others
• Similarities are evidence of hereditary
relationships among species
Whale Evolution
• http://www.youtube.com/watch?v=I2C3PjNGok