Topic 10: How do living things evolve?

1
Topic 10 How do living things evolve?
2
Inorganic to Organic

• How could life have begun?

3
Miller Urey 1953
Simulated Earths early atmosphere
Mixed H2, CH4, NH3 (important no Oxygen)
Produced organic molecules from inorganic
molecules
4
Evolution doesnt depend on how life first began
but instead Evolution deals with the mechanisms
of change
5
Biological Evolution
Simple species change over time

• Complex allele frequencies in populations
  change over time

6
Early Evolutionary Thought
7
Anaximander(611 547 BC)
Earth was first in a liquid state

• Humans evolved from fishlike creatures who left
  the water

8
Empedocles(400s BC)
Humans and animals arose as various body parts
joined together randomly

• Some unable to reproduce, become extinct, others
  thrived (natural selection ??)

9
Lucretius (94 55 BC)

• . . . the preservation of animal life in
  accordance with the law of the survival of the
  fittest

Wrote about
10
Plato(427? 347 BC)
Ultimate reality ?ideal forms
On Earth ? imperfect copies

• Variation ? not important

11
Aristotle(384 322 BC)
Species ? unchanging ideal form
Successful creatures ? perfecting
principle

• Variation is noise

12
Scala Naturae
Fixed species
Hierarchical scale
Perfecting principle

• Variation - noise

13
Important ideas prevail
Fixed unchanging Species
Scala Naturae (simple ? complex)
Perfecting principle

• Variation is not important

14
Christian Philosophy
God ? Creation
No organisms appeared or disappeared and no change

• Humans unique

15
James Ussher(1581 1656)
Irish Prelate Biblical Scholar

• Creation on 22 Oct 4004 BC at 900 AM

16
Static, divinely ordered world

• Predominant way of thinking not only in religion
  and philosophy but also in science

17
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

18
John Ray (1628-1705)
Father of Natural History in Britain

• Searched for the natural system ?
  classification of organisms reflecting Divine
  Order of creation

19
Carolus Linnaeus (1707-1778)
To discover order in the diversity of life for
the greater glory of God
20
William Paley (1743 1805)

• The metaphor of the watchmaker

21
. . . 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. . . .
22
. . . . 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.
23
Challenges to Established Views
Astronomy
Nicholas Copernicus (1473 1543)

• Heliocentric Model

24
Challenges to Established Views
Global Exploration
New areas -- new information

• Plants and animals ? never seen before

25
Challenges to Established Views
Geology
Existence of Fossils
Species extinction

• Age of Earth

26
Fossils
Extinct species?
Where did they come from?

• Why did they die out?

27
Cuvier (1769 1832)
Theory of Catastrophe (multiple creations
separated by catastrophes)

• World and inhabitants stable and specially created

Earth is older than scriptures suggest
28
James Hutton- (1726 1797)
1st scientific challenge to static world
Geological processes constant

• Earth ? very old

29
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

30
Erasmus Darwin - (1731 1802)
Charles Darwins Grandfather
Formulated one of the early theories of evolution

• But no mechanism

31

• Suggestions organisms could evolve no one
  explanation how and why organisms changed over
  time

32
Jean-Baptiste de Lamarck(1744 1829)
Mechanism for Evolution

• Interaction of organisms and environment

33
LaMarck - Philosophie zoologique
"First Law" ? use or disuse causes structures to
enlarge or shrink

• "Second Law" ? all such changes were heritable.

34
Lamarckian Giraffes
35
Jean-Baptiste de LamarckIncorrect Assumptions
Theory teleological (goal directed)

• Characteristics acquired during life of organism
  passed on to their offspring

36
Charles Darwin - (1809 1882)
Enter Charles Darwin
Physician -Theologian - Naturalist

• Prevailing view one of Gods static perfect
  world

37
Darwin on the HMS Beagle
Joined as the Naturalist

• Primary commission of the Beagle was to map the
  coastlines and harbors of South America

38
Route of the Beagle
39
Major impacts on Darwins thinking as he sailed
on the HMS Beagle
40
Observes shell exposed bed on land (some shells
same as modern species)
must have been underwater at one time, then
uplifted
41
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).
42
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.

43
Fossils of extinct animals
Fossils outnumber living forms?

• Driven to extinction?

44
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

45
(No Transcript)
46
BiologyGalapagos Islands
Island organisms (endemic) similar to mainland
organisms

• tortoises finches

47
Saddle-backed tortoises are found on low, arid
islands
Dome-shaped tortoises are found on high, humid
islands
48
Darwins Finches
Different species with different shaped beaks

• All descendents of mainland ground finch

49
Return Home
Discussed ideas wrote brief essay (early 1840s)
Worked on other studies rather than publish
evolution
Read Malthus (and others)

• Letter from Wallace

50
On the Origin of Species
Published on 24 November 1859

• 20 years after voyage

51
(No Transcript)