Transcript The Theory of Evolution

The Theory of Evolution
Evolution:

The most famous scientist that studied and
discussed evolution is Charles Darwin.
 In 1831 Charles Darwin undertook a five
year scientific study on the H.M.S. Beagle.
 He traveled to the Galapagos Islands
where he discovered his greatest proof to
support evolution.
 On the Galapagos islands Darwin discovered
an interesting bird, the Finch.
Evolution continued:

Darwin observed that Finches had
different beak sizes on different islands
dependent on the food resources
available to them.
What is a theory?

In everyday use, the word "theory" often
means an untested hunch, or a guess without
supporting evidence.
 But for scientists, a theory has nearly the
opposite meaning.
 A theory is a well-substantiated
explanation of an aspect of the natural
world. It can incorporate laws, hypotheses
and facts.
What is evolution:
Evolution is the genetic change of
organisms over time.
 This genetic change may give the
organism a survival and/or
reproductive advantage in their local
environments.
 Population increases usually
accompany these changes and this
increased rate of survival is known as
natural selection.

The Theory of Evolution:
Supporters of the theory of evolution believe
that all living things developed from one
simple form of life.

From this ‘unknown’ ancestor
organisms adapted according to their
environment and gave birth to the
diverse species seen in the fossil
record.
The Theory of Evolution:

There are four essential requirements of
evolution:
– V = Variation: All life forms vary genetically
within a population. It is this genetic variation
upon which selection works.
– I = Inheritance: Genetic traits are inherited
from parents and are passed on to offspring.
– S = Selection: Organisms with traits that are
favorable to their survival get to live and pass on
their genes to the next generation.
– T = Time: Evolution takes time. Evolution can
happen in a few generations, but major change,
such as speciation, often takes long periods of
time.
The Theory of Evolution:

There are also four ways in which evolution
occurs:
– Mutation: a change in an organisms DNA usually
caused by an error in repair or duplication
– Migration: occurs when an organism inserts its
DNA in a different species pool
– Genetic Drift: random changes in gene
frequencies of a species (could be caused by
environmental factors)
– Natural Selection: process in which some
individuals have genetically-based traits that
improve survival or reproduction and and thus
have more offspring
The Theory of Creation:
Many people believe in creationism.
 This is the belief that man (and all
other beings) were placed on earth by
a higher being, God.
 For many this belief is grounded in the
book of Genesis.

– Chapter 1, Verse 27: “So God created man
in his own image, in the image of God
created them; male and female created
them.”
The Theory of Creation:

Believers in creation suggest that the major
plants and animals on earth were placed
on the earth in their final form.
 This also suggests that man/women were
placed on the earth in his/her current fully
human form.
 In this view, earth was not a spontaneous
creation but rather a specific and planned
event by our creator.
Theories on the Origin of
Humankind – Pre-Darwinism

Diluvial Theory:
– supported the Bible
– fossils of extinct animals formed by Noah’s flood

Objections:
– no single event like Flood could account for
progression of fossils in layers, each lower level is
older
– discovery of pre-flood fossils related to animals
living after the flood
Theories on the Origin of
Humankind – Pre-Darwinism

Catastrophe Theory – George Cuvier
(1769-1832)
– explained sequence of fossil layers by proposing a
corresponding series of major catastrophes
interspersed with periods of calm when plant and
animal populations restocked the Earth
– Noah’s flood just one of many catastrophes
(between 27-32)

Objection:
– fossil record looks like “jerky” catastrophes but
change was much more gradual
Contemporary Creationism

Intelligent Design
– promotes the idea that natural processes
and living things are best explained by an
intelligent cause and not undirected,
Darwinian natural selection

Common Objection: not scientifically
verifiable, should not be considered a
“scientific theory”
What is the big deal anyways?

Why was (is) the theory of evolution so
controversial?
– At the time of Darwin’s publication of the Origin of
Species (1859) creation was the most widely
accepted version of how the earth and all life on it
was created.
– To many it seemed that the theory of evolution
was an attempt to contradict religious belief.
– But, Darwin himself was deeply religious.
– The idea that humans came from apes was also
offensive to some people.
Misconceptions about the theory
of Evolution:
1.
Evolution is a theory about the origin of
life.
Misconceptions continued:
2. Evolution is like a climb up a ladder of
progress; organisms are always getting
better.
Misconceptions continued:
3. Evolution means that life changed ‘by
chance’.
Misconceptions continued:
4. Natural selection involves organisms
‘trying’ to adapt.
Misconceptions continued:
5. Natural selection gives organisms what
they ‘need’.
Origin of Species Synopsis
1.
2.
3.
IF you have creatures that vary…
IF there is a struggle for life that killed
most species that ever lived…
IF the few that do survive pass on
whatever genes helped them to
survive…
THEN YOU GET…
The Evolutionary Algorithm:

If you have:
– Variation
– Inheritance
– Selection
And
- Time

Then you get evolution
Activity:

Think about this question:

At what point in ‘the evolution of humans’
do you believe that these primates begin
to become human? (Ex. when they begin
to walk on two feet or use tools) Why?