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Evidence for
EVOLUTION
Fossils

A fossil is the naturally preserved remains or traces of animals or plants
that lived in the geologic past. There are two main types of fossils; body
and trace. Body fossils include the remains of organisms that were once
living and trace fossils are the signs that organisms were present (i.e.
footprints, tracks, trails, and burrows).

http://imnh.isu.edu/digitalatlas/geo/basics/fossil.htm

http://www.ucmp.berkeley.edu/science/trackways/trackways2.php
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http://www.amnh.org/exhibitions/permanent-exhibitions/fossil-halls/hall-of-ornithischian-dinosaurs/dinosaur-mummy
Megalodon fossil record
 Megalodon lived 10 million years ago
Megalodon’s bite force was
41,000lbs compared to TRex’s bite force of 13,000 lbs.
http://www.fossilguy.com/gallery/vert/fish-shark/carcharocles/carcharocles.htm
Evidence in layers of sediment

Sediment is pieces of minerals, plants, animals and other organic matter.

Sediment is deposited and compressed over time with the oldest layers being the
deepest layers and the newest layers are the layers we see below our feet.

Compressed sediment is called rock.

Layers of sediment form strata which can be seen in cliffs
Fossils have never
been discovered in
the “wrong” layer.

http://www.prehistoricplanet.com/news/index.php?id=48
Homologous structures indicate a common
ancestor
Vestigial Structures - A feature that an organism inherited
from its ancestor but that is now less elaborate and
functional than in the ancestor.
http://evolution.berkeley.edu/evolibrary/article/0_0_0/lines_05
Embryology – embryos of several different species share similarities.
In an early stage of the human embryo a
gill slit and a tail is present similar to fish
and primates.
Note: this image is a simplified artists rendition to
convey a complex concept.
Putting it all together
https://www.youtube.com/watch?v=O21VOcLIb3M
https://www.youtube.com/watch?v=lIEoO5KdPvg
Charles Darwin
Liked to collect
and study beetles.
Born 2/12/1809
In 1831, went on a 5 year journey on the HMS Beagle
as their naturalist.
The finch species Darwin studied on the
Galapagos Islands were important in developing
Darwin’s ideas of natural selection.
Darwin’s Influences
• Darwin’s ideas were influenced by an essay he read in 1838 that was
written by Thomas Malthus titled, “Essay on the Principle of
Population.”
• Malthus said that in nature, plants, animals and even humans produce
more offspring than can survive. He thought that human population
growth would lead to an insufficient food supply and thus keep the
population in check.
• Darwin applied and extended Malthus’ theory to his own. He concluded
that variations among offspring would produce some offspring who are
better equipped to survive and reproduce in a competitive environment.
Darwin’s Influences Cont’d.
Darwin struggled with 2 social influences during his time in history. People believed:
1. The Earth was thousands of years old.
2. All species were created at one time and never changed over time.
Darwin had, however, observed similarities among species all over the globe. Some of
the changes were consistent with changes in locations. This lead him to believe that
these species gradually evolved from a common ancestor. Species that developed
adaptations that helped them survive in their habitat reproduced and passed the
adaptive trait on. Those that did not have the favorable adaptation, failed to reproduce
as often and eventually died off. This became know as the theory of NATURAL
SELECTION.
Darwin also read a book called “Principles of Geology” by Charles Lyell that provided
evidence that the Earth was much older than anyone ever thought. This new
understanding supported Darwin’s view that evolution is a very slow process in which
small changes can accumulate over long periods of time.
Alfred Russel Wallace
In 1859 Alfred Russel Wallace had reached the same conclusion about
evolution as Charles Darwin. Wallace had also gone on an expedition
during which he studied many plant and animal species around the
world. He wrote a scientific paper and sent it to Darwin for review.
Darwin had been holding off on publishing his ideas because he wanted
to stockpile an abundance of evidence. Also, he know his ideas may not
be accepted due to the prevalent religious social setting of the time. He
was astounded to read Wallace’s work and discover that it was almost
identical to his own theories. He and Wallace published together, then
Darwin published his famous and widely accepted book, “On the Origin
of the Species by Means of Natural Selection.”
Natural Selection
I have called this principle, by which each slight variation, if useful,
is preserved, by the term Natural Selection.
- Charles Darwin, The Origin of Species
Natural Selection is the process by which organisms that are better
adapted to their environment survive and reproduce more successfully than
less well adapted organisms do.
4 Parts of Natural Selection
1. Overproduction – The environment can’t support
unlimited population growth. There will be
competition for resources and not all offspring can
survive to reproduce.
2. Variation – Each offspring is similar to, but not
identical to its parent. Therefore there is variation
among offspring.
3. Struggle to Survive - Organisms that are better
suited to survive in their environment will live longer
and reproduce more. The less well adapted will die
off.
4. Heredity – Those organisms with traits that help them
survive will reproduce more and pass on those traits
through heredity. Eventually the favorable trait will
take over the population and the less favorable trait
will die off.