Transcript Darwin`s Theory of Evolution by Natural Selection “The single most

Darwin’s Theory of Evolution
by Natural Selection
“The single most important
scientific idea that anyone has
ever had.”
“Evolution is just a theory”
Like…
GERM
CELLS
ATOMS
RELATIVITY
GRAVITY
Evolution: Isn't Evolution Just a Theory?
What is a scientific theory?
theory: A well-substantiated explanation of some
aspect of the natural world that typically incorporates
many confirmed observations, laws and successfully
verified hypothesis.
How is a scientific theory
different from a plain old
talk-at-the-dinner-table
theory????
TAKE A MINUTE AND WRITE A
PARAGRAPH EXPLAINING THE
DIFFERENCE
SCIENCE
is…
“an organized way of using evidence
to learn about the NATURAL
world.”
Point, blank, period.
Charles Darwin
• Born in England Feb. 12, 1809
• Held a degree in theology from Cambridge
University and had considered becoming a
preacher
• After college he joined the crew of the HMS Beagle
and set sail in 1831 for a trip around the world
• During this voyage he made observations, collected
data, and developed his hypothesis on the origin of
species
• Published “On the Origin of the Species” in 1859
and rocked the world!
What questions did Darwin ask?
As he observed patterns of diversity, “Why
aren’t animals the same everywhere?”
Considering fossils and modern animals,
“Why are some fossils the same as modern
species while many have disappeared?”
On the living things seen on the Galapagos
Islands, “Why are they similar to things
living on the mainland but not exactly
alike?”
Ideas that shaped Darwin’s thinking
European concepts of the day included
1. Earth and all of its life forms had
been created only a few thousand
years ago.
2. Since their creation, neither the
Earth or its species had changed.
Discoveries that changed these
perceptions
A rich fossil record which showed
previous extinctions and led some
scientists to suggest there had been
several “creations”
The Earth was very old- how do we
know???
1. James Hutton- concluded that
geologic forces had changed the
Earth over millions of years
2. Charles Lyell- proposed that
scientists must explain past events
in terms of processes that can be
observed today-principle of The
Uniformity in the Order of Nature
How do we know
who had the right
idea???
How did the Grand Canyon
form?
We know:
• The Grand Canyon was formed by the
Colorado River
• The river is currently eroding rock
layers at a rate of 0.3 m/millenium
• The canyon is 1800 meters deep in
some places.
Using this rate of erosion, how long did
it take for the canyon to form?
Soooooo…
Can the Earth be only a few
thousand years old?????
How “long is evolution”?
If one whole lifetime (100 years) is like walking
a mile, then the amount of time that evolution
had is not just like walking all the way from
California to Africa- it is like walking to the
moon, and back, a hundred times over!
I repeat, if a hundred years is like walking a
mile, then evolution walked all the way to the
moon and back a hundred times over!!!
238, 857 miles
• Time Zero: 13-14 billion years ago all galaxies,
all matter, all of space compressed into a hot,
dense volume about the size of the sun and
then…
a stupendous nearly instantaneous expansion
and distribution of all matter and energy in the
universe…the BIG BANG!!!
And then???
• Next billion years saw the formation of stars as gaseous
particles collide and condense under gravities force
• 4.6 billion years ago clumps of debris formed our solar
system including Earth (which by the way, was a very
nasty place with a very different atmosphere, sky was
probably pink, not blue, due to its chemical make-up)
• 3.8 billion years ago rain began eroding mineral salts
from rocks which ran off and collected to form oceans
The scene had been set for some very interesting
developments….
WHAT DO WE KNOW?
•
The basic timeline is a 4.5 billion year
old Earth, with (very approximate) dates:
•
3.8 billion years of simple cells
(prokaryotes),
3 billion years of photosynthesis,
2 billion years of complex cells
(eukaryotes),
1 billion years of multicellular life,
600 million years of simple animals,
570 million years of arthropods
(ancestors of insects, arachnids and
crustaceans),
550 million years of complex animals,
500 million years of fish and protoamphibians,
475 million years of land plants,
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
400 million years of insects and seeds,
360 million years of amphibians,
300 million years of reptiles,
200 million years of mammals,
150 million years of birds,
130 million years of flowers,
65 million years since the non-avian dinosaurs died out,
2.5 million years since the appearance of the genus Homo,
200,000 years since humans started looking like they do today,
25,000 years since the disappearance of Neanderthal traits from the
fossil record.
13,000 years since the disappearance of Homo floresiensis from the
fossil record.
HOW???
Evolution is…
•Change over time
•Change in a species
•Change in the frequency of an
allele in a population
What are the components
of
Darwin’s Theory of
Evolution?
Variation exists
within a species
All organisms
compete for
limited natural
resources.
Organisms
produce more
offspring than can
survive.
The environment
selects organisms
with beneficial
traits.
NATURAL
SELECTION
Traits are passed
on to offspring.
Darwin’s Theory of Evolution by Natural
Selection
1.Variation exists within a species
2.All organisms compete for limited natural
resources
3.Organisms produce more offspring than
can survive.
4.The environment selects organisms with
beneficial traits.
5.Traits are passed on to offspring.
So exactly where in his theory did Charles
Darwin say humans came from monkeys?
NO WHERE!!!