Download Darwin`s Theory - Hicksville Public Schools

How was Darwin’s Theory Shaped
by other scientists?
• Lamarck (1744-1829)
• Darwin (1809-1882)
Lamarck’s Theory of Evolution:
Inheritance of Acquired Characteristics
• An organism will change during life in
order to adapt to its environment.
• Those changes are passed on to its
offspring.
• Change is made by what the organisms
want or need.
• Body parts that are not used, gradually
disappear.
• “pre-determined plan”
Lamarck Believed…
• Giraffes stretched
their necks to reach
food.
• Offspring and later
generations
inherited the long
necks.
Lamarck’s Theory of Evolution:
1. Recognized that all living
things changed over time, and
have descended from other
species.
Lamarck’s Theory of
Evolution:
2. Laws of Use and Disuse:
Organs / Structures used would
remain strong and functional,
while those not used would
disappear.
Lamarck’s Theory of Evolution:
3. Inheritance of Desired Traits:
– Traits acquired due to
adaptations to the environment
were passed on to offspring
August Weismann
• Cut off the tails of mice and
allowed the mice to mate.
• The offspring were born with
tails.
• DISPROVED Lamarck’s theory.
Darwin
•Considered the
“father” of evolution.
Charles Darwin traveled to the
Galapagos island, an uninhabited
environment, where he studied
evolution (Darwin’s Finches)
Darwin Believed
• Organisms (even within species) are
all different and those which happen
to have variations that help them
survive in their environments. Those
that survive have more offspring.
• Offspring are born with their parents’
helpful traits, and they reproduce, and
that trait makes up more of the
population.
More on Darwin…
• Individuals that are not well adapted,
die off.
• example: Some Giraffe’s had short
necks, some had long necks. When
lower food sources became scarce,
giraffe’s with longer necks survived
because they could get food.
• Ex2; Elephants and trunk size/water
Darwin’s Theory of Evolution
Natural Selection:
• Individuals with favorable traits
are able to survive and
reproduce.
• Nature controls which traits are
favorable.
How They Agreed
• Both thought life had changed
gradually over time (and still
changing)
• Living things change to be better
suited (Adapted) to their environments
• All organisms are related
• Life evolved from fewer simpler
organisms to many, more complex
ones
Why we believe Darwin
• Weisman’s experiment.
• Other observations: people who
exercise, run a lot, eat well and
generally healthy and fit do not have
children who are inherently healthy
and fit, the children have to work at it.
• Gene sets that are in a population
determine the traits there are. Genes
sets are determine by which
individuals die and which survive.