Transcript Theory of Evolution

Darwin’s Evolution
A Theory of Evolution
How did the giraffe
get its long neck?
Lamarck had an idea…
 Organisms acquire traits.
 Organisms evolve.
 Pass their acquired traits
to their offspring.

Lamarck
Can I “get buff” and then have “buff” kids?
 Can I study and get really smart and then
have genius kids?

How did the giraffe
get its long neck? DARWIN
Organisms don’t
evolve, species
evolve.
 Within a population
there are variations
among organisms.
 Genetic Diversity from
sexual reproduction
and mutations.
 They are born that
way.

How did the giraffe
get its long neck?
These different
individuals had an
advantage over the
others in its herd.
 Survival of the
fittest.
 Organisms don’t
adapt, species
adapt through
natural selection.

Mutant!
How did the giraffe
get its long neck?
This mutant has more
children than the rest
of the population
because it is better
adapted to the
environment.
 The population
evolves so that all the
individuals become
like the mutant.

How did the giraffe
get its long neck?

Eventually all giraffes
have long necks.
The Theory of Evolution
Organisms within a species have
variations.
 Organisms struggle for survival and
reproduce at different rates.
 Natural selection – the environment
determines which variation is the best.
 Survival of the fittest - those with the best
variation will out survive the ones without
it.

Adaptations
Organisms born with a unique variation that
allows them to survive in an environment.
 Variations that give them an advantage over
those who don’t have that variation.
 Which dog has an adaptation?

Hand Variation
in a Human Population
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