Acquired characteristics

1
Lecture 4
Charles Darwin - was he a quack?
2
What is Evolution?

• Evolution is technically defined as "a gradual
  process in which something changes into a
  different and usually more complex or better
  form."
• As it is most famously used, "evolution" is the
  process by which an organism becomes more
  sophisticated over time and in response to its
  environment.
• The Theory of Evolution is currently the most
  popular concept of how life reached its current
  state. -Evolution as a biological mechanism is
  driven by natural selection.
• This theory is favored by many scientists to
  explain phenomena in nature, so much so that it
  is generally assumed as factual in most studies.

3
Definition

• Biological evolution, simply put, is descent
  with modification - C. Darwin.
• This definition encompasses
• small-scale evolution (changes in gene frequency
  in a population from one generation to the next)
  and
• large-scale evolution (the descent of different
  species from a common ancestor over many
  generations).
• Evolution helps us to understand the history of
  life.

4
Biological Evolution

• Biological evolution is not simply a matter of
  change over time.
• Lots of things change over time
• trees lose their leaves
• mountain ranges rise and erode,
• but they aren't examples of biological evolution
  because they don't involve descent through
  genetic inheritance.

5

• The central idea of biological evolution is that
  all life on Earth shares a common ancestor, just
  as you and your cousins share a common
  grandmother.

6

• Through the process of descent with modification,
  the common ancestor of life on Earth gave rise to
  the fantastic diversity that we see documented in
  the fossil record and around us today.
• Evolution means that we're all distant cousins
  humans and oak trees, hummingbirds and whales.
• and slime moulds, and spiders

7
Evolution is a science

• Sometimes the best way to understand science is
  to review the history rather than understand the
  logic

8
Very early ideas

• Cavemen (75,000 B.C. to 10,000 B.C.)
• What could they have pondered over?
• Ask the Geico Caveman

9
Early ideas

• 550 B.C.
• A Greek philosopher, Miletus, argued that the
  Earth was not created abruptly
• life had started as slime in the oceans
• later moved to land
• humans and other vertebrates had descended from
  fish.

10
Before Aristotle

• 454 B.C.
• Another Greek philosopher, Empedocles, speculated
  that animals developed from plants
• The Universe and all in it is gradually changing

11
Aristotle

• Aristotle (384 - 322 B.C.)
• Suggested that all species are static
• All species can be arranged according to the
  degree of perfection
• Created by God
• Great Chain of Being
• These ideas went unchallenged until the 17th
  century in the Western World

12
John Ray

• 1627-1705
• Classified over 18,000 plants
• Proposed the first definition of a species
• Maintained that species do not change
• He was concerned about the fossil record evidence
  emerging at the time!
• He is the Father of Botany

13
Carl von Linne

• Better known by his Latin name - Carolus Linnaeus
  (1707 - 1778)
• In 1735 he tried to classify all life on Earth,
  in order to discover a pattern of the creation
• He wanted to classify Man in a group alone but
  failed to find a scientific reason to do so, and
  grouped with other apes.

14
Acquired characteristics - Biological evolution
is gene based

• A regular and sustained program of weightlifting
  yields enlarged muscles, an immediate
  physiological response of muscles to the
  increased effort. However, these big muscles
  remain with the individual that endured the
  regular exercises, and are not passed to their
  offspring. This is because the enlarged
  characteristics result from individual effort,
  not from an inheritable genetic change.

15
Evolutionary predecessors

• Over the years before Darwin, many biologists
  attempted to solve the mystery of the species
  question.

16
Who was Charles Darwin?
17

1. Charles Robert Darwin was born in Shrewsbury,
   Shropshire, England on 16th Feb 1809
2. His father (Robert Waring Darwin) and grandfather
   (E. Darwin) were both doctors
3. His mother was Susannah Wedgewood Darwin was the
   daughter of a Josiah Wedgewood - founder of
   Wedgewood China
4. He had one brother and four sisters
5. He attended Shrewsbury Grammar School, but
   preferred to hunt and collect shells and coins.
   He also enjoyed learning Latin and Greek.

18

• Darwin Family Tree

19
(No Transcript)
20

• In 1825 he enrolled at Edinburgh University to
  study medicine, where he learned about taxidermy
  (useful later in his life)
• He dropped out because he did not like the
  classes.
• He had failed his family!!
• In 1827 he enrolled at University of Cambridge
  and began to study to become a clergyman
• However, he preferred to collect insects!!!
• It was at Cambridge that he began to appreciate
  the vast diversity of species
• His professors were followers of Lamarcks ideas
  about inheritance of acquired characters
• He also learnt natural theology - Understand God
  by studying Gods creation

21

• Darwin did graduate from Cambridge at age 23 with
  a B.Sc. Degree in Theology
• Before joining the Church of England he wanted to
  travel - as it was the great time of exploration.
• He wanted to visit exotic locations before
  settling down to religious work.
• In 1830, the British government commissioned a
  90-foot ship -HMS Beagle - devoted to the
  acquisition of knowledge. It was really to test
  new clocks and find new sources of wealth.
• Darwin, through a contact at Cambridge, was
  recommended as an alternative and signed up as
  the ships unpaid naturalist

22

• The Beagle sailed more than 40,000 miles from Dec
  1831 to Oct 1836
• Darwin spent 18 months at sea and the rest of
  the time on land
• Of the 58 month voyage, he spent 43 in South
  America
• He visited the Galapagos Islands where he made
  his most profound observations.
• This time would transform his life and biology!

23
(No Transcript)
24
Galápagos tortoise
25

• Whilst on the voyage he was given a book to read
  by the captain - this book would transform
  Darwins thinking
• The book was written by Lyell, who had put
  together all the previous arguments about the age
  of the Earth and geological time, providing real
  examples of geological changes that shaped the
  planet.
• When Darwin boarded The Beagle he was a firm
  believer in the clergy and the fixation of
  species - when he disembarked he was a changed
  man and wanted to discover the laws of nature!
• Then back on England Darwin began to put all the
  pieces together.

26

• Another book that Darwin read, sealed the deal
  for him
• A manuscript published by Thomas Malthus implied
  that given ideal conditions a population would
  grow exponentially
• However, the resources would not grow in the
  same fashion - they would grow linearly
• Therefore, at some time the population would
  exceed the resources and there would be a
  struggle for existence
• Darwin put together the short term struggle for
  existence (Malthus) with the great geological
  timescale (Lyell)

27
Galápagos finches

• Analysis of these finches led scientists to
  hypothesize that they were derived from one
  ancestor arriving from the mainland to populate
  and diversify across the islands.

28
(No Transcript)
29
Evidence supporting evolution

• The Fossil record
• Common Structures
• Species Distribution
• Developmental Similarities
• DNA sequence comparisons

30

• Rock layers
• Carbon dating

31
(No Transcript)
32
Common Structures

• Man
• Pig
• Horse
• Whale
• Bat

33
Species Distribution
34
(No Transcript)
35
Developmental Similarities
36
DNA sequence comparisons
37
(No Transcript)
38
Break
39
Link to the video clips

• http//www.pbs.org/wgbh/evolution/educators/teachs
  tuds/svideos.html

40
Evolution is not real

• Evolution is just a theory!
• Watch this clip and answer these questions
• http//www.pbs.org/wgbh/evolution/educators/teachs
  tuds/svideos.html
• Is a theory just as simple guess?
• What is an inference?
• What did Darwin infer?

606
41
Darwins Dilemma

• Watch this clip and try to understand the self
  turmoil which he went through
• http//www.pbs.org/wgbh/evolution/educators/teachs
  tuds/svideos.html
• Which ship did he travel on?
• Which idea became clear to him?
• What courage did Darwin have?
• Where is he buried?

636
42
How does evolution work?

• Watch this short video and answer these questions
• http//www.pbs.org/wgbh/evolution/educators/teachs
  tuds/svideos.html
• Natural Selection is really composed of which
  components?
• How is the length of the humming bird bill
  determined?

641
43
Did humans evolve?

• Watch this short video and tackle these
  questions
• What is a common ancestor?
• Is it the same as a chimpanzee?
• Which species does not have DNA?
• How similar is our DNA to chimps?

534
44
Why care about evolution?

• Has profound health and welfare issues
• Watch and answer these questions
• Do bacteria evolve?
• How about viruses?
• What is the leading infectious killer of adults
  today?

619
45
What is controversial about evolution?

• Watch this important clip and digest
• What was the evil book?
• Must you have to choose between faith and
  evolution?

634
46
Religion and Evolution

• The late Pope John Paul II said openly that
  evolution happened
• Many very orthodox people refuse to accept
  evolution at all
• Scientists base their theories on evidence that
  can be tested - evolution is a very solid theory
  at this time
• Many religious commentators attack single aspects
  of the evolution theory
• It is Religion which cannot be tested in this
  manner, as we first need evidence to begin

47
Ken Ham

• Watch this clip of Ken Ham - a biblical
  literalist
• http//www.pbs.org/wgbh/evolution/library/08/1/rea
  l/l_081_04.html
• What is his angle on evolution?
• What proof does he provide for his views?
• How does he explain the finding of fossils?
• What is questionable with his interpretation?

606