Transcript Darwin*s Theory of Evolution

Concept 14.1 pp 292-298
• Species are fixed, permanent,
unchanging
• The Earth was less than 10,000
yrs old and unchanged.
• Awareness of diversity- plants,
animals, geological processes
people began to challenge these
ideas.
• Biological history of life.
• Changes over a long time that transforms
life.
Influences:
1. *Fossil Study-Georges Buffon
– Earth is much older
– Specific fossils and certain animals may
be similar but not identical
– Suggests a common ancestor.
2. *Lamarck first proposed life changes or
evolves.
– Stated species are not permanent
• Lamarck thought using or not using
certain body parts allowed organisms
to developed characteristics that
could be passed on to offspring.
• Incorrect- no scientific evidence to
support this.
• DNA /genes need to be modified.
• Lamarck was describing
environmental effects.
• An inherited characteristic
that improves an organism’s
ability to survive and
reproduce in a particular
environment.
• Examples of adaptations-
3. Darwin’s Voyage
• 1831- HMS Beagle
• 5 year voyage.
• Darwin made observations in South
America.
• Plants and animals of South America are
distinct from species of Europe.
• Species living in South America were
descended from an ancestral species on that
continent.
• Darwin’s observations cause him to
question his view.
• A chain of volcanic island off west coast of
South America.
• Darwin notices most species are similar, but
different from the nearby mainland.
• Darwin infers species changed and adapted
after they colonized the islands.
4. *Lyell’s geological studies influence Darwin
– Gradual – slow processes
– Erosion and earthquakes explain fossils of
marine animals found in the Andes.
– Conclusion- Earth must be very old.
5. *Malthus essay- Human suffering
– Human population growth rate is
increasing faster than food and
resources are available.
– Limiting factors.
– Darwin realizes this concept applies
to all species.
6. *Alfred Wallace describes the same
idea of evolutionary change.
– Prompts Darwin to publish his
ideas.
• Darwin – published in 1859.
• 2 main points1. Descent with modification-
explains diversity of life.
•Species on Earth today descended
from ancestral species.
•They spread into various habitats
occurred over millions of years.
•In their habitats they accumulated
different modifications ( adaptations).
•Examples of adaptations.
2. Natural Selection
• Individuals with inherited characteristics
that are best suited will leave more
offspring.
• Over time this can cause a change in the
characteristics of a population.
• Natural Selection is a cause of evolution.
• Adaptation is the result of evolution.
• Natural Selection differs from selective
breeding which occurs in a shorter time
frame because man picks those to breed.