Download Descent with Modification

Charles Darwin and
Natural Selection
Darwin’s Ideas Influenced by:
 Voyage on the Beagle (1831-1836)
 Lamarck’s Theory of Evolution
 Also influenced by…
Geologists James Hutton and
Charles Lyell
• Hutton
– Processes that form rock, mountains, and
valleys are very slow
– Earth is much more than a few thousand
years old
• Lyell
– Geological processes we observe now have
occurred for millions of years
– Explains why marine fossils are at tops of
mountains
Thomas Malthus, Economist
Babies born faster than people dying
If population growth continued, people
would run out of food, water and space
War, famine and disease prevents this
Fossils
Artificial Selection
 Breeders
select best traits to produce
next generation
Darwin’s Theory of Evolution
by Natural Selection

Living things overproduce
Darwin’s Theory of Evolution
by Natural Selection

There is variation among offspring
Darwin’s Theory of Evolution
by Natural Selection

There is a struggle to survive
Darwin’s Theory of Evolution
by Natural Selection

Those that survive are most fit
Natural Selection:
“Survival of the Fittest”


Fitness = ability to survive and
reproduce
Fitness is the result of adaptations –
inherited characteristics that increase
an organism’s chance of survival
Descent with Modification



Over time, natural selection produces
organisms with different structures
Today’s species look different from
their ancestors
Each species descended with changes
over time
Descent with Modification


Implies that all living things are related
to one another
COMMON ANCESTOR