Transcript Evidence for Evolution

Evidence for Evolution
Evolution on trial
Earth is 4.6 billion years old and the oldest
evidence of life is 3.6 billion years old.
If this mechanism of change has been
shaping the organisms on this planet, then
there should be evidence of it occurring
5 major types of evidence used to support
the theory of evolution.
1. Fossil Record
Skeletons, bones, impressions, etc. of organisms no longer found living
on the planet.
 Radiometric and relative dating suggests life is billions of years old
 Activity
 The older the fossils the more simple and the greater the differences
between existing organisms
 Incomplete and includes inferences
2. Biogeographical
The study of the geographic distribution of organisms
 Islands of the world have species found no place else.
(13 different species of finch on Galapagos, aquatic
iguanas, Hawaiian honeycreepers, etc.)
 Marsupials found in both Australia and S. America. Few
placental mammals in Aus; many in S. America. Results
in a wide diversity of marsupials in Australia and low
diversity of marsupials in S. America
 Organisms that are similar on different continents are
that way b/c adapted to similar ecosystems
3. Anatomical
Outside appearance of body parts of similar
categories of organisms may look and function
differently
 If internal structures are examined lots of
similarities exist.
 Ex. Forelimbs in vertebrates
 Homologous Structures: Structures in different
species that are similar in makeup, and may
have different functions.
 Wings of bat, forelimbs of dog
3. Anatomical Cont.
 Analogous Structures: Structures in
different species that have different
makeup but have same function.
 Wings of bat and wings of bee
 Vestigial Structures: Any structure that is
reduced in function.
 Results in reduction of size. (ex. Human
Appendix / wisdom teeth, whale pelvic bones,
ostrich wings, dew claw on dogs and cats.)
4. Embryological Development
The stages of
development
from zygote
to embryo
are the same
for all
animals.
5. Genetic Comparisons
Comparing the base pairs of similar genes,
and/or amino acid sequences of similar proteins
from different organisms
 The more similarities the closer related.
 60% of human genes are fundamentally the
same as fruit fly genes.
 90% the same as mice
 96% similar to chimpanzees
 All humans are 99.9% the same genetically