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TURN
EOCT Lesson #37-38
IN TO
THE BASKET
How Populations Evolve
Chapter 14 The History of Life
14.1 Fossil Evidence of Change
Land Environments
The History of LifeChapter
14
Earth formed about 4.6 billion years ago.
Gravity pulled the densest elements to the
center of the planet.
After about 500 million years, a solid crust
formed on the surface.
Clues in Rocks
The History of Life
A fossil is any preserved evidence of an
organism.
Most organisms decompose before they
have a chance to become fossilized.
14.1 Fossil Evidence of Change
Chapter
14
Fossil Formation
The History of Life
Nearly all fossils are formed in sedimentary
rock.
The sediments build up until they cover the
organism’s remains.
Minerals replace the organic matter or fill the
empty pore spaces of the organism.
14.1 Fossil Evidence of Change
Chapter
14
The History of Life
14.1 Fossil Evidence of Change
Chapter
14
Dating Fossils
The History of Life
Relative dating
determines the age
of rocks by
comparing them
with fossils in other
layers.
14.1 Fossil Evidence of Change
Chapter
14
uses the decay of
radioactive
isotopes to
measure the age
of a rock
Radiometric Dating
The History of Life
14.1 Fossil Evidence of Change
Chapter
14
Paleontologists are the scientists that study fossils.
Describes the movement of several large plates
that make up Earth’s surface.
Provides evidence of where and when extinct
organisms lived and/or migrated.
The History of Life
14.1 Fossil Evidence of Change
Chapter
14
Plate Tectonics
15.1 Darwin’s Theory of Natural Selection
Darwin on the HMS Beagle
Evolution
Darwin’s role on the ship was as naturalist.
His job was to collect biological and
geological specimens during the ship’s
travel.
Chapter
15
The Galápagos Islands
Evolution
Darwin collected finches and other animals on
the islands.
He noticed that
each island
seemed to have
its own unique
varieties of
animals.
Chapter
15
Evolution
Darwin thought that animals from S. America
had migrated to the Galápagos long ago.
Darwin hypothesized that new species could
appear gradually through small changes over
many generations.
Chapter
15
• Darwin saw natural selection as the basic mechanism of evolution
– As a result, the proportion of individuals with favorable characteristics increases
– Populations gradually change in response to the environment
Ideas That influenced Darwin
Jean Baptiste Lamarck stated
that by selective use or disuse
of organs, organisms acquired
certain traits during their
lifetime. These traits could then
be passed on to offspring.
Lamarck’s theory was
incorrect in several ways but
important because it paved
the way for other biologists.
Chapter
15
Evolution
Thomas Malthus predicted that the human
population will grow faster than the space and
supplies needed to sustain it.
Darwin realized that this applied to plants and
animals, and that the overwhelming majority of
a species’ offspring die.
Chapter
15
Evolution
Darwin Continued His Studies
Evolution
Darwin spent time reviewing the thousands of
specimens, fossils, and pages of notes he had
written. He spent 20+ years doing this before he
published his book.
15.1 Darwin’s Theory of Natural Selection
Chapter
15
Wrote “On The Origin of Species” in 1859 after
Alfred Russell Wallace sent him an essay
stating almost the same theory – Darwin
thought “now or never”.
Wallace thought all changes in a species were
due to natural selection – Darwin knew that
there were other causes. (will discuss later)
15.1 Darwin’s Theory of Natural Selection
EvolutionChapter
15
EvolutionChapter
15
Darwin called his theory
natural selection.
Over time, natural selection causes
changes in the entire species’
characteristics.
“SURVIVAL OF THE FITTEST”
