Transcript An explanation of observations

I. Theory of Evolution
A. Overview
1. "Theory vs. Scientific Theory"
a. "Theory" in everyday language is a guess
b. "Scientific Theory" is supported by a large amount of
evidence. An explanation of observations.
2. Definition of Evolution -- Change in a population over
time
a. The smallest unit that can change is a population.
b. An organism does not evolve, a population does.
B. An early idea about how evolution occurred:
Lamarck: French naturalist, published his hypothesis in
1809.
1. Lamarck’s Theory was based on his observations
a. He observed that blacksmiths had big muscles and
that family members stayed in the profession.
b. organisms constantly strive to improve self and
become more advanced.
c. effort to improve causes the most used body
structures to develop while the unused body
structures wasted away (Use Disuse theory)
d. the modification due to use or disuse is passed on to
offspring (Inheritance of Acquired Characteristics)
e. Another example he used is giraffes necks
3. Weismann (1889): Proves Lamarck wrong through an
experiment.
a. cut off the tails of mice for 22 generations.
b. All offspring were born with tails.
c. He concluded that changes in the body during your
life are not passed down to offspring. (we know this
now through genetics)
C. Charles Darwin
1. growing up years
2. education
3. Voyage of the Beagle (1831-1836)
a. purpose of the voyage was to make maps of coast of
South America
b. Darwin’s purpose was to make geological studies to
locate minerals for mining…he was also the ships
naturalist.
c. Darwin observed plants and animals every time they
docked.
d. He noticed slight differences in them based on where
they were
e. He collected fossils and made notes about where he
found them.
4. Visit to the Galapagos
Islands during his voyage
a. Local Finches (a type of
bird) had different types of
beaks based on what they ate
b. Tortoises had different
shells based on what island
they were on
c. Why were they different?
How did they get that way?
5. Darwin’s Theory was influenced by 3 people
a. Charles Lyell – wrote a book explaining that changes in
the Earth were slow and uniform
Darwin – slow Earth changes could affect plants and
animals
b. Thomas Malthus – observed that the human population
was growing so fast that the supply of resources would
not be able to support the population
Darwin – There was always competition for food,
space, and mates. Those that “win”
survive and reproduce.
c. Pigeon and Dog Breeders – select animals with the best
traits to get the desired pigeon or dog
Darwin – thought this process would naturally
occur, but slower.
6. Darwin’s Theory of how evolution has occurred:
Natural Selection
a. There is a variety within a population
b. Some traits are an advantage to have (they improve the
organisms chance to reproduce)
c. More young are created in each generation than can
survive
d. Those that survive and reproduce are those with the
traits that are an advantage to have
e. Over a long time, small changes accumulate and the
population changes.
7. Darwin did not publish his theory for more than 20 years.
He published On the Origin of Species in 1859.
Lamarck
Darwin