Transcript Development of Theory of evolution

Unit 2: Evolution
Learning Goal 1:
Examine the history of
the development of the
theory of evolution.
Scientific Theory

A well supported testable explanation of
phenomena that have occurred in the natural
world.
Charles Darwin (1809-1882)



First attended the University of Edinburgh to become
a surgeon.
Transferred to Cambridge to study theology and
become an Anglican priest.
Graduated at the age of 22 (1831) and joined the
HMS Beagle.
–
–
Father did not want him to join the ship because it might
lead him away from a future in the clergy.
Started as the captains companion and later became the
ship’s naturalist.
Five-Year Voyage
HMS Beagle
http://evolution.berkeley.edu/evolibrary/home.php
http://evolution.berkeley.edu/evolibrary/home.php
www.darwinday.org/englishL/life/beagle.html
www.darwinday.org/englishL/life/beagle.ht
Used by permission of Darwin Day
Celebration (at DarwinDay.org), 2006
I have called this principle, by which
each slight variation, if useful, is preserved,
by the term Natural Selection.
—Charles Darwin from "The Origin of Species"
http://evolution.berkeley.edu/evolibrary/home.ph
Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
Darwin’s Observations

Patterns of Diversity
–
Darwin observed similar animals that were
diverse in their characteristics.
Darwin’s Observations

Fossils
–
–

a large part of the puzzle.
A fossil is preserved remains
of ancient organisms.
Many animals found in
fossils were very similar to
modern day organisms.
Galapagos Islands

Darwin observed that the characteristics of
many plants and animals varied noticeably
among the different islands.
Galapagos Islands

Each island had a very different climate.
–
The smallest, lowest islands were hot, dry, and
nearly barren.

–
Sparse vegetation
Higher islands had greater rainfall.

Different assortment of plants and animals.
Island Tortoises

Darwin found that the shape of the shell of
the tortoise varied from island to island.
–
You could use the shape of the shell to determine
where the tortoise had come form.
Galapagos Iguanas
Galapagos Iguanas



The iguanas seemed to adapt to their
environments.
Those that lived near trees had feet and
claws adapted for climbing in soft tissue.
Those that lived on rocky cliffs had feet and
claws adapted to climbing on rocky cliffs.
Darwin’s Finches

Darwin found finches around the islands that
had beak types that were specific to the
types of food available.

that

soft
*Those with big thick beaks ate seeds
were available.
*Those with smaller beaks ate the
flesh of fruit or insects.
Darwin’s Finches
Origin of Evolutionary Thought

Charles Darwin developed the central
idea of evolution by natural selection,
but others before and during his time
also built essential parts of the theory.
James Hutton


1785
Proposes that Earth is shaped by forces
that took place over extremely long periods
of time.
Proposed Earth to be millions of years old.
Thomas Malthus

Human populations will grow
faster than the space and
food supplies needed to
sustain it.
– Competition
1798
Jean-Baptiste Lamarck
1809

Publishes his hypothesis of
the inheritance of acquired
traits.
–
–
Ideas were flawed.
The first to propose a
mechanism explaining
how organisms change
over time.
Charles Lyell


Publishes Principles
of Geology
Explains that processes
occurring now have
shaped Earth’s geological
features over long
periods of time.
1833
Alfred Wallace



Independently drew the same
conclusion as Darwin.
Evolution by Natural Selection
Conferred with Darwin about
ideas.
1858
On the Origin of Species


Published in 1859
Proposed a mechanism
for evolution called Natural Selection
–
–
Organisms changed over time as a result of
the change to their environment.
Those best suited for their
environment would survive
and pass on their traits.