Transcript Presentation 10 (pp)

Topic 10: How
do living things
evolve?
Inorganic to Organic
• How could life have begun?
Miller & Urey – 1953
Simulated Earth’s early
atmosphere
Mixed H2, CH4, NH3
(important no Oxygen)
Produced organic
molecules from
inorganic molecules
Evolution doesn’t depend on how life first began
but instead Evolution deals with the
mechanisms of change
Biological Evolution
Simple – species change over time
Complex – allele frequencies in
populations change over time
Early Evolutionary Thought
Anaximander
(611 – 547 BC)
Earth was first
in a liquid state
Humans evolved from fishlike
creatures who left the
water
Empedocles
(400’s BC)
Humans and animals arose
as various body parts
joined together randomly
Some unable to reproduce,
become extinct, others thrived
(natural selection ??)
Lucretius (94 – 55 BC)
Wrote about:
. . . the preservation
of animal life in
accordance with
the law of the
survival of the
fittest
Plato
(427? – 347 BC)
Ultimate reality ideal
“forms”
On Earth  imperfect
copies
Variation  not important
Aristotle
(384 – 322 BC)
Species  unchanging
“ideal form”
Successful creatures
 “perfecting” principle”
Variation is “noise”
Scala Naturae
Fixed species
Hierarchical scale
Perfecting principle
Variation - noise
Important ideas prevail
Fixed unchanging Species
Scala Naturae (simple  complex)
“Perfecting principle”
Variation is not important
Christian Philosophy
God  Creation
No organisms appeared
or disappeared and no
change
Humans unique
James Ussher
(1581 – 1656)
Irish Prelate &
Biblical Scholar
Creation on 22 Oct
4004 BC at 9:00 AM
Static, divinely ordered
world
Predominant way of thinking not only
in religion and philosophy but also
in science
Natural Theology
Nature of God understood by reference to His
creation  natural world
Inspired naturalists to look at form in the context of
function
laid the groundwork for evolutionary studies of
adaptation and fitness
John Ray (1628-1705)
“Father” of Natural
History in Britain
Searched for the “natural
system”  classification of
organisms reflecting Divine
Order of creation
Carolus Linnaeus (1707-1778)
To discover order in the diversity of life “for
the greater glory of God”
William Paley (1743 – 1805)
The metaphor of the
watchmaker
. . . when we come to inspect the watch, we perceive.
. . that its several parts are framed and put together
for a purpose, e.g. that they are so formed and
adjusted as to produce motion,
and that motion so regulated as to point out the hour
of the day; that if the different parts had been
differently shaped from what they are, or placed after
any other manner or in any other order than that in
which they are placed,
either no motion at all would have been carried on in
the machine, or none which would have answered
the use that is now served by it. . . .
. . . . the inference we think is inevitable, that the watch must
have had a maker -- that there must have existed, at some time
and at some place or other, an artificer or artificers who formed
it for the purpose which we find it actually to answer, who
comprehended its construction and designed its use.
Living organisms, are even more complicated than watches,
"in a degree which exceeds all computation." How else to
account for the often amazing adaptations of animals and
plants?
Only an intelligent Designer could have created them, just as
only an intelligent watchmaker can make a watch: Only an
intelligent Designer could have created them, just as only an
intelligent watchmaker can make a watch:
That designer must have been a person. That person is GOD.
Challenges to Established Views
Astronomy
Nicholas Copernicus
(1473 – 1543)
Heliocentric Model
Challenges to Established Views
Global Exploration
New areas -- new information
Plants and animals 
never seen before
Challenges to Established Views
Geology
Existence of Fossils
Species extinction
Age of Earth
Fossils
Extinct species?
Where did they come
from?
Why did they die out?
Cuvier – (1769 – 1832)
Theory of Catastrophe
(multiple creations separated
by catastrophes)
World and inhabitants stable
and specially created
Earth is older than scriptures
suggest
James Hutton- (1726 – 1797)
“1st” scientific
challenge to static
world
Geological processes
constant
Earth  very old
Lyell (1797 – 1875)
Theory of Uniformitarianism
Natural laws constant in time
& space
Events of the past explained by
processes observed today
Geological changes occur slowly
and gradually not as
catastrophes
Erasmus Darwin - (1731 – 1802)
Charles Darwin’s
Grandfather
Formulated one of
the early theories of
evolution
But no mechanism
Suggestions organisms could evolve no one
explanation how and why organisms
changed over time
Jean-Baptiste de Lamarck
(1744 – 1829)
Mechanism for
Evolution
Interaction of organisms and
environment
LaMarck - Philosophie zoologique
"First Law"  use or disuse
causes structures to enlarge or
shrink
"Second Law"  all such changes were
heritable.
Lamarckian
Giraffes
Jean-Baptiste de Lamarck
Incorrect Assumptions
Theory teleological (goal directed)
Characteristics acquired during life of
organism passed on to their offspring
Charles Darwin - (1809 – 1882)
Enter Charles
Darwin
Physician -Theologian Naturalist
Prevailing view one of
God’s static & perfect
world
Darwin on the HMS Beagle
Joined as the “Naturalist”
Primary commission of the Beagle was to
map the coastlines and harbors of
South America
Route of the Beagle
Major impacts on Darwin’s thinking
as he sailed on the HMS Beagle
Observes shell exposed bed on land (some
shells same as modern species)
must have been underwater at one time, then
uplifted
January 16, 1832, the H.M.S. Beagle, made its first stop at
São Tiago in the Cape Verde islands off the west coast of
Africa.
Years later, Charles Darwin wrote:
"The geology of St. Iago is very striking yet simple: a
stream of lava formerly flowed over the bed of the sea,
formed of triturated recent shells and corals, which it baked
into a hard white rock.
Since then the whole island has been upheaved. But the line
of white rock revealed to me a new and important fact, namely
that there had been afterwards subsidence round the craters,
which had since been in action, and had poured forth lava.
It then first dawned on me that I might write a book on the
geology of the countries visited, and this made me thrill with
delight. That was a memorable hour to me. . . .”
(Autobiography, p. 81).
Darwin experiences an earthquake in Chile
. . . “I happened to be on shore . . . Lying in the
woods to rest myself. It came on suddenly and
lasted two minutes, but the time appeared much
longer.
The motion made me almost giddy: it was
something like . . . That felt by a person
skating over thin ice, which bends under the
weight of the body.”
Fossils of extinct
animals
Fossils
outnumber living
forms?
Driven to extinction?
Biological - Diversity of Plants & animals
Huge diversity of
plants and animals
Differ from continent
to continent
Rhea (4), Emu (6),
Ostrich (8)
Separation caused
differences
Biology
Galapagos Islands
Island organisms (endemic) similar to mainland
organisms
tortoises & finches
Dome-shaped tortoises
are found on high,
humid islands
Saddle-backed
tortoises are found on
low, arid islands
“Darwin’s Finches
Different species with different shaped beaks
All descendents of mainland ground finch
Return Home
Discussed ideas – wrote
brief essay (early 1840’s)
Worked on other studies
rather than publish “evolution”
Read Malthus (and others)
Letter from Wallace
On the Origin of
Species
Published on
24 November 1859
20+ years after
voyage