Evolution of life?

1
Evolution of life?

• What is evolution?

2
What are the main ideas of the following
Scientists about the evolution of life?

• Aristotle
• Lamarck
• Darwin
• Mendel
• Lysenko

3
Aristotle (384-322 BC)

• "Aristotelianism
• Partly based on Plato's world of ideas
• The species are given categories in nature and
  are unchangeable
• There are only variation in mature and perfection
  of individuals
• The only development is the mature of each
  individual where the aim is to reach perfection
  which is given in the ideal types of the species

4
Aristotles epigenesis I.

• All living creatures, whether they swim, or walk,
  or fly, and whether they come into the world with
  the form of an animal or of an egg, are
  engendered in the same way.
• Concept of epigenesis and that in the embryo,
  more generalized structures appear before the
  more specialized ones.
• Epigenesis was one correct idea of Aristotle that
  was often discarded.

5
Aristotles epigenesis II.

• His concepts of heredity were even sounder than
  Darwin's (!)
• Darwin believed in pangenesis (gemmules from all
  parts of the body migrate to the semen and
  account for paternal characteristics).
• This was an old idea that Aristotle had refuted
  by fairly sound reasoning, among them
• children sometimes resemble distant relatives
  more than their parents. This couldn't occur if
  the genetic particles were obtained by direct
  transmission.
• children of mutilated/crippled parents do not
  display these mutilations
• both male AND female contribute to the
  characteristics of the offspring.

6
Jean-Baptiste de Monet, chevalier de Lamarck
(1744-1829)

• "Lamarckism
• French enlightenment
• Naturalist and pre-Darwinian evolutionist
• Studied fossils and invertebrates
• Species change over time by adapting to new
  environments
• Parents pass their traits on to their offspring
• If an organ is used, it will become stronger,
  and if it is not used, it will weaken and may
  disappear in future generations
• He postulated that acquired characters can be
  inherited by future generations

7
Charles Robert Darwin (1809-1882)

• Natural selection" / "Darwinism
• By variation in the population there is an
  adaption to the environment through a natural
  selection of acquired characters represented in
  the variation of the species
• Darwin's concepts of heredity were that gemmules
  from all parts of the body migrate to the semen
  and account for paternal characteristics
• Evolution purely mechanistic process

8
Gregor Mendel (1822-1884)

• Mendelian genetics
• His principle of factorial inheritance and the
  quantitative investigation of single characters
  have provided the basis for modern genetics.
  Recognition came many years after his death, when
  his key article, Experiments with plant hybrids
  (1866), was discovered.

9
The major insights attributed to Mendel are often
summarized in two "laws"

• Principle of Segregation
• observable traits are passed down to offspring
  via (discrete, non-blending) particles, one from
  each parent.
• Principle of Independent Assortment
• the particles (later dubbed genes by American
  geneticist T. H. Morgan) from each parent are
  equally likely to be passed down to offspring.

10
T. H. Morgan 1866-1945

• Through study of Drosophila
• Made an elegant proof that the chromosomes are
  indeed the bearers of the hereditary factors or
  genes as they are now known

11
Trofim Denisovich Lysenko (1898-1976)

• Lysenkoism
• developed a doctrine, compounded of Darwinism and
  the work of Michurin, that heredity can be
  changed by good husbandry.
• As director of the Institute of Genetics of the
  Soviet Academy of Sciences (194065), he declared
  the accepted Mendelian theory erroneous, and
  ruthlessly silenced any Soviet geneticists who
  opposed him.
• He was dismissed by Khrushchev in 1965, having
  gravely hampered scientific and agricultural
  progress in the USSR.

12
James Watson 1962- Francis Crick 1916-2004

• Figured out the structure of deoxyribonucleic
  acid, DNA.
• And that structure a "double helix" that can
  "unzip" to make copies of itself confirmed
  suspicions that DNA carries life's hereditary
  information.

13
Discussion questions

1. What is evolution? Explain and exemplify!
2. Does evolution have an aim?
3. Does evolution have a purpose?

14
Modern view on evolution

• Our very best evidence indicates that, in
  reality, all species in this world have equal
  lengths of evolutionary history.
• The differences are the result of coincidence in
  the pathways evolutionary movement takes.
• Evolution is ultimately about diversity, not
  about progress and without purpose or aim

15
(No Transcript)
16
(No Transcript)
17
(No Transcript)