Transcript Die (Ir-)Rationalität religiöser Überzeugungen

Philosophical presuppositions
of evolutionary biology
FFDI Zagreb, 20-25 April 2015
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Prof.Dr.Dr. Winfried Löffler
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University of Innsbruck
Department of Christian
Philosophy
Karl-Rahner-Platz 1
A-6020 Innsbruck, Austria
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[email protected]
www.uibk.ac.at/philtheol/loeffler
1.
Aims & method of this lecture
2.
The received view: Aristotle’s
biology
3.
Evolutionary ideas until Darwin
4.
History of evolutionary thought
from Darwin to the present
5.
Evolution: Theory-structures and
concepts
6.
Evolution between science and
world-view
7.
Summary & discussion
1. Aims and method of this lecture
Aims:
Some basics about current evolutionary biology
Some basics about its historical backgrounds
Understand its peculiar theoretical status
Distinguish between scientific theory and its ideological interpretations /
reductionisms
Misunderstandings of anti-evolutionism
Method: historical (2-4, partly 6) to understand conceptual backgrounds
2. The received view: Aristotle’s biology
2.1 Life and Works
Aristotle (384-322)
today usually seen as philosopher,
but first big encyclopedist
Almost all scientific disciplines:
- Physics, biology, physiology, meteorology, psychology,
- economics, politology, aesthetics / poetology
- ethics, rhetorics, philosophy of language,
- philosophy of science
- general philosophy (“first philosophy”, metaphysics)
Influential merits in the philosophy of science:
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Important basic concepts (substance/accident, potential/actual,
matter/form, efficient cause/final cause)
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Classification of the scientific disciplines
(theoretical/practical/poietical); (episteme / historia / techne)
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Structure of scientific arguments (Prior Analytics, syllogism)
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Structure of scientific classifications
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Structure of an empirical science (empirical “first sentences” & logical
derivations from them) – overcoming Platonism
Heavy influence on Western thought!!!
2.2 Biological writings
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Historia animalium (History of Animals) - see later
De partibus animalium (Parts of Animals)
De generatione animalium (Generation of Animals)
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Smaller writings (On movement of animals, sleep and sleeplessness,
breathing, life and death etc.)
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Biggest part of his work is natural science!
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Interestingly: little interest in medicine (son of a healer!) and botany
2.3 Aristotle’s method in biology
Empirical (broad sense) with speculative assumptions
Classification of phenomena plus question for causes (“4 causes”)
Reports of “experts”, own observations
Maybe: “experiments”, anatomical sections (stages of fertilized eggs)
Only scarcely: quantification (lengths); not weights, food intake etc.
Only scarcely: ecological view (what it eats)
Aim: Collection/classification of facts (historía) and research for causes
2.3 Aristotle’s method in biology
Teleology without design:
Natural things seen as functional units with functional parts
Teleological world-picture:
Chief pattern of explanation: final explanation, what is it good for?
Example: why do animals with a lung also have a neck? De part.An.III,3
(Roughly): Bipartite lungs need some tube to partition the air; that tube
needs a certain length, hence the windpipe. Hence also, the
oesophagus/jednjak. Hence, the necessity of a neck. (Fish don’t need
one). The vicinity of windpipe and oesophagus is technically bad and
would cause trouble; hence, nature contrived the epiglottis.
Nature as a whole is rational. Natura nihil facit frustra. Form follows function
BUT: No external “design plans”.
2.4 Aristotle’s taxonomy
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550 species according to morphological criteria, 300 re-identifiable
today
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Groups and similarity observations: e.g., “all live-bearing quadrupeds
have lungs and windpipes”
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Attempts to a classification of the whole range of animals,
morphological features; not always consistent and sometimes wrong
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Man is included as a sub-class!
2.4 Aristotle’s taxonomy
An example from HA IV 1, 524a3-20: “The octopus uses its
tentacles both as feet and as hands; it draws in its food with the two
that are placed over its mouth. The last of them, which is very sharp
and is the only one which is whitish in colour and bifurcated at the
tip—it is made so as to uncoil on the rhachis side (the rhachis being
the smooth surface of the tentacle away from the suckers)—this one
it uses in the act of copulation. In front of the sac and above the
tentacles they have a hollow tube, by means of which they
discharge from the sac any sea-water which may have come in
while taking food into the mouth. The animal can move this tube to
right and to left; it also discharges its “ink” through it. It swims
obliquely in the direction of the so-called head, stretching out its feet;
and by swimming in this way it can see forwards (since its eyes are
on top), while its mouth is at the rear. So long as the animal is alive,
the head is hard and as it were inflated. It takes hold of things and
retains them with the underside of its tentacles, and the membrane
between its feet is kept extended in its entirety. If it gets on to the
sand, it can no longer retain its hold. […]”
Aristotle’s taxonomy (roughly):
Animals with blood: (today: vertebrates)
Live-bearing quadrupeds
Egg-laying Quadrupeds
Birds
Fish
Cetacea (sea mammals)
Egg-laying footless (snakes)
Live-bearing footless (vipers)
Man
Animals without blood:
Cephalopods
Molluscs
Insects
Crustaceans
2.5 The stability of species
Fundamental for 2300 years.
Minimal traces of evolutionary ideas?
(1)
“Libya always produces something new” (De gen.an. II,7):
crossing of animal species at waterholes; reflection about the infertility of
hybrids
(2)
Reflection about Empedocles’ (5.century BC) mythical explanation of the origin
of life: plants first, then parts of animals, then animals, only the useful ones
survived
Aristotle: random combinations would not have survived (Phys. II, 8)
(3)
Knowledge about variation: not all animals conform to species, monstrosities,
freak animals etc. (Not worrifying, just “freaks of nature”)
2.6 Astonishing pioneerhoods and errors
Pioneerhoods:
Sexual life of octopus
Opposition to preformation theory / homunculus theory of the sperm (until 19th
century!). “Epigenetic”, step by step, formation of organs – the important ones
for the genus-membership first.
Errors:
Bison throws feces 7m for defense
Women have less teeth
Dayfly has only 4 legs
Speculations:
Parthenogenesis and other forms of reproduction
Procreation (in mud etc.) – until Pasteur, 19th century!
Brains serve to cool blood
Women are incomplete men (more influence of katameria than of sperm)
Women get soul later, birth rates m/f have to do with winds
3. Evolutionary ideas until Darwin
3.1 Some aspects of biology after the middle ages
Renaissance:
• Excursions, geograph. discoveries, herbaria, museums
• flourishing of anatomy (Andreas Vesalius, Fabrica
(1543; De humani corporis fabrica libri VIII);
public section of corpses; previously unknown
exactness;
descent-line: apes – “pygmies” (Plinius!) – man)
17th cent.:
• new science of nature (Bacon, Galilei)
Experiments (planned variation of conditions, protocols)
• New tools of observation: microscope, telescope; discovery
of micro-organisms, fine structures, insect development
• “Physico-theology” & speculative preformationism
(1695)
(hot discussions 18th cent. (Spallanzani), end 1830!)
3.2 Carl von Linné’s taxonomy
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Various attempts to classifications,
morphology comes in focus (microscopes!)
Tension: Theory still Aristotelian (tree / pyramid), experience
shows multiplicity and similarities across branches
“Natural history” becomes a discipline of its own
Carl von Linné (Linnaeus), 1707-1778; Swedish medic and botanist
Reform of taxonomy, 3 merits:
a)
New system of plants, with classification method (according to
number and structure of reproduction organs; “sexual system”)
Systema naturae 1735; Genera plantarum 1737 etc.
b) Binary nomenclature (instead of descriptions), e.g. Sambucus nigra
(sambucus = genus, sambucus nigra = species)
c)
Terminology for the parts of plants
3.2 Carl von Linné’s taxonomy
Backgrounds of Linné’s thought:
Objective structures in nature, ideas of the divine creator.
Not Aristotelian essentialism, but rather Enlightenment’s ideal of ordering
Does classificatory relatedness imply anything about historical relatedness?
Does the Systema point to a relation?
Linné understood it as an artificial system with the task of
ordering/quick finding; “natural system” as final project at horizon.
Growing discontent about Linné´s artificiality.
Some unclear remarks about an origin of plants
Controversial how firmly he believed in the stability of species
3.3 Early French speculations about evolution
Georges Buffon (Histoire Naturelle, 36 vols., 1753-1788):
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Complexity and similarities in nature make a Linnéan classification
impossible. And: “species” is an abstractum; there are individuals
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Procreation and change, by climate etc. Related species might have
common ancestors, maybe one. Earth out of a collision sun-comet.
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Evolutionary scale/ladder instead of Linné´s hierarchical classification
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Evidence: similar anatomy across many species (donkey/horse,
man/ape, man’s foot / horse’s foot etc.); rudimentary, useless organs
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Indirect message: EITHER God made the species by variation of few
plans (great!), OR they have a common history. (Officially, the first…)
3.3 Early French speculations about evolution
Georges Cuvier (1769-1832), Étienne Geoffroy Saint-Hilaire (17721844) and the Paris Academy Dispute 1831:
Idealist versus evolutionary morphology?
Cuvier: “King of functional anatomy”, fine drawings, function determines
structure, structure allows conjecture to function. “Reconstruction of
died-out animals out of a few bones.”
Four basic construction plans of animals
Yet firm opposition to any evolutionary change (cats from Egypt, …)
Fossils are just extinct species, in global/regional catastrophes.
No “intermediate forms” in fossils
Geoffroy St.Hilaire: Research in homologies (e.g. gill bones in fish – ear
bones in humans; vertebrate is similar to inverted worm (nerves at
back, intestinal at front). Hence, change of species, common ancestry.
Political relevance: (1) not ideas of God (2) ...if not even nature is stable?
3.4 Romanticist Philosophy of Nature and Morphology
Johann W. von Goethe (1749-1832):
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“morphology” instead of “comparative anatomy”: plants
and animals represent certain ideal shapes/forms/construction plans (mostly superficial, restricted to outer form)
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speculations about construction plan of a “Urpflanze”
(ideal plant) which is realized in variants in real plants
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Postulates that skull bones are modified rib bones
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Discovers the intermaxillary bone in human embryos: since humans
represent general mammal plan, and all other mammals have it, it
must be somewhere… - in embryonal development!
“Göttingen School” (Carl Friedrich Kielmeyer, Johann Friedrich Meckel,
Lorenz Oken, influenced by Fichte and Schelling): “Recapitulation”:
Development of the embryo recapitulates animals of lower complexity
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Partly empirical (embryology, anatomy), partly philosophical:
“formative power” of nature etc.; idealist “great chain of beings”
3.4 Romanticist Philosophy of Nature and Morphology
Richard Owen (1848): Theory of “archetypes” (ideal design plans).
Background: similar organs in very different animals (mole’s hand &
dolphin’s fin have same bones!) cannot be due to environment.
Archetype of all vertebrates:
Terminological proposal, used till today:
Homologous organ: same construction, different function (e.g. mole’s
hand, dolphin’s fin)
Analogous organ: different construction, same function (e.g. bird’s and
butterfly’s wing)
3.5 The first “evolutionary theory”: Lamarck 1809
Jean Baptiste de Lamarck (1744-1829): Philosophie zoologique (1809)
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“Lamarckism” today: inheritance of individually acquired
characteristics, usually seen as overcome since Darwin; partial revival
today
First evolutionary theory: a theory that & how species change in the
course of time.
Simple forms of life emerge constantly from anorganic matter,
procreation; hence, no common ancestry
Inner tendency to higher development, “complexifying force”: le
pouvoir de la vie
Organisms adust behaviour to environment and inner state
Use/disuse of organs leads to growth/change of organs (e.g. neck)
… and that change is inherited!
As with Geoffroy St.Hilaire later: politically dangerous ideas…
3.5 The first “evolutionary theory”: Lamarck 1809
Jean Baptiste de Lamarck (1744-1829): Philosophie zoologique (1809)
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“First Law: In every animal which has not passed the limit of its
development, a more frequent and continuous use of any organ gradually
strengthens, develops and enlarges that organ, and gives it a power
proportional to the length of time it has been so used; while the permanent
disuse of any organ imperceptibly weakens and deteriorates it, and
progressively diminishes its functional capacity, until it finally disappears.”
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“Second Law: All the acquisitions or losses wrought by nature on
individuals, through the influence of the environment in which their race
has long been placed, and hence through the influence of the
predominant use or permanent disuse of any organ; all these are
preserved by reproduction to the new individuals which arise, provided
that the acquired modifications are common to both sexes, or at least to
the individuals which produce the young.”
3.6 Erasmus Darwin (1731-1802) and a widely forgotten
Anonymous: Robert Chambers (1844)
Erasmus Darwin (grandfather of Charles Darwin and Francis Galton)
Speculative views about Lamarck-style evolution:
“Would it be too bold to imagine, that in the great length of time, since the
earth began to exist, perhaps millions of ages before the commencement of
the history of mankind, would it be too bold to imagine, that all warm-blooded
animals have arisen from one living filament, which the great first cause
endued with animality, with the power of acquiring new parts, attended with
new propensities, directed by irritations, sensations, volitions, and
associations; and thus possessing the faculty of continuing to improve by its
own inherent activity, and of delivering down those improvements by
generation to its posterity, world without end!”
Glimpse of natural selection
[R. Chambers] Vestiges of the Natural History of Creation (1844)
Popular science book, rather speculative, many errors
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Author: Robert Chambers, Scotch writer, anonymous
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Variability of species; Man descends from simpler forms of life
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Popularity and (slowly starting) excitement
4. History of evolutionary thought
from Darwin to the present
4.1 Charles Darwin (1809-1882) – life and works
Son of a religion-skeptic physician & unitarian
Studies briefly medicine, natural history, theology; future: parson?
No professional education as a scientist (biology not yet established!)
Invitation to travel on mapping-ship Beagle 1831-36
Collects, studies, draws, sends
samples home
Initially only few doubts about
stability of species
Influences:
Charles Lyell (geologist, big changes
of the earth surface; but rejects
Lamarckism; species are created;
they die out due to external change,
and suppression by other species)
Richard Owen and Romantics
Erasmus Darwin
Lamarck (via Robert E. Grant!)
Increasing doubts in Lyell’s biology (not in his geology!):
• released domestic animals adapt quickly to new environment
• two similar ostrich species in overlapping areas (why does the one
not repress the other one?)
• why do species dies out without change in environment?
• why are died-out mammals replaced by other, similar ones?
• the finches from the Galapagos islands:
- related with each other, related with
animals on the continent,
- different birds in similar habitats!
- No clear-cut line “species” - “variety”
Back in Cambridge
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Orders his findings, discusses (with Lyell, Owen, J. Gould (finches!))…
Early speculations about an explanation for relations
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1837: first sketch “I think”, insight that
species must be changeable
Darwin’s speculations still +/- Lamarckist:
- changes/variations are always useful, since
- adaptation to environment as an embryo,
geograph. isolation may cause new species
- changes are inheritable
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1838: reads Thomas Malthus: Essay on the
Principle of Population
Populations have tendency to grow infinitely,
but limited resources cause concurrence and limit growth,
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 Darwin: Selection not as embryo, but after birth.
Theory of natural selection was +/- finished by 1839 (diaries).
The Theory of Natural Selection
• Random, undirected, inheritable variations
PLUS
• natural selection under the pressure of the environment, concurrence for
food etc. …
• … may in the long run lead to the emergence of adaptive (=useful)
change and new species.
• I.e., variations need not be perfect anymore. Old idea of perfect
adaptation (from natural theology!) abandoned. Variations need just be
slightly better.
• A manuscript was finished by 1842. Why not published? (1) Fear of
scandal (Vestiges 1844!)? (2) Darwin had not yet a good idea for the
ramifications / divergences in the changes.
• After 1854: Sympatry (different species in same area) is more important
than Allopatry (different species in isolated areas). Coherent with the
facts. Reason: Big areas have more ecological niches!
The Publication and its effects
1856
1858
1858
1859
Darwin presents his ideas to Lyell etc., friends urge to publish
Alfred Russel Wallace sends a manuscript to Darwin, similar ideas
Common paper by Darwin and Wallace, Wallace admits priority
On the Origin of Species by Means of Natural Selection
Public effect:
In England dampened by a theol. discussion about
correct Bible interpretation 1860, and Vestiges
John Herschel (astronomer, 1792-1871): unscientific, since only statistical
Thomas Huxley (“Darwin’s Bulldog”) tries to elicit
cultural discussion, free universities, no religion
Not even whole church opposes. Still: excitement.
In France Cuvier dominates, no big interest
In Germany: bestseller, quick translation, popularized
by Ernst Haeckel (materialist reading!)
Later Publications
1871
1872
The Descent of Man (no big scandal; evolution of moral behavior)
The Expression of Emotions in Animals and Man
Works about coral reefs,
plant fertilisation, rainworms, etc.
Darwin and religion:
1851
Death of his daughter, loss of religious faith, respectful agnostic
1882
Tomb in Westminster Abbey
4.2 The Five Basic Tenets of Darwin’s Darwinism (E. Mayr)
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Evolution: species come and go through time, and while they exist they
change. (But: the real bearer of evolution is the individual, not the
species!)
Common descent
Species multiply: the diversification of life involves populations of one
species diverging until they become separate species
Gradualism: evolutionary change occurs through incremental small
steps; new species are not created suddenly.
Natural selection: some variants change individual’s survival &
reproduction probability.
Against Lyell: species are not stable; not perfectly adapted to
environment; species are not created quickly (Lyell was a theory of
species sequence, not of species evolution!)
Against Lamarck: individual changes are not inherited; common
descent
4.3 Darwin’s Speculations about the biological fundament
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Notabene: Darwin had no idea about the place and nature of genetic
information, laws of inheritance (Mendel’s rules etc.)
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Theory of Pangenesis: all cells produce little “gemmulae” (little buds),
they gather in reproduction organs. In the young they mix
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= a Lamarckist remainder in Darwin!
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Still even in 1868 (book on selective breeding of animals and plants).
Soft inheritance, acquired traits are passed on.
4.4 Some open questions in Darwin
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Small steps or jumps? (Is mutation or selection the more important
driving force of evolution?)
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Why sudden speeding up of evolutionary change, rapid growth of
species numbers in certain stages of earth history (“Cambrian
explosion” etc.)
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No real theory about inheritance, similarity and variability
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Why is there life at all? No procreation (no conflict with Pasteur 1859);
maybe 4 or 5 original forms of life. Reference to creator more courtesy?
Speculation about the warm little pond (letter to Hooker 1871):
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“But if (and Oh! What a big if!) we could conceive in some warm little pond,
with all sorts of ammonia and phosphoric salts, light, heat, electricity etc,
present, that a protein compound was chemically formed ready to undergo
still more complex changes...”
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Similarity to Miller-Urey experiment 1953, “primordial soup” …
The Miller-Urey experiment
4.5 Ernst Haeckel (1834-1919): Materialism with idealist traces
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Great graphic illustrator, popularizer in Germany
Materialist (Darwinism as anti-religious and anti-conservative program!)
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Yet: some idealist remainders, idea of dynamics of growing complexity:
– takes on recapitulation-idea of Kielmeyer
– Creates terms, and “biogenetic fundamental law”:
“ontogeny” repeats “phylogeny”
– Evolutionary morphology: similarity of gastrula stage;
 speculation to a “Gastrea” as common ancestor
 “tree of life” suggests height
of development, dynamics to
complexity.
(false: successful simple organisms,
backward-developments)
4.6 Francis Galton (1822-1911): Evolution becomes statistical
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Cousin of Darwin, multidisciplinary scientist: statistics, fingerprints,
efficacy of prayer, questionnaire, blood-transfusion, eugenics
Experiments against Darwin’s “gemmulae”
semi-lamarckian speculative theory of inheritance
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Important: Separation Organism – genetic information (“stirp”).
Organism is just a representative selection from stirp, like a parliament
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Inheritance becomes statistical matter, every parent contributes ½
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Variation is now a matter of the population (not the organism, not the
species!). New subject of evolution. Farewell to Aristotelian ideas.
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Beginning of theoretical biology as a mathematicised discipline!
4.7 August Weismann (1834-1914): The organism as mere vehicle
of genetic information
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Radical materialist
Similar to Galton, but with more empirical justification: experiments
with sea urchins (ježinac): germ cells are separated from the rest of
the organism in very early stage
 Separation germ cells – somatic cells
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Half-speculative theory of
“immortal germ plasm”.
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Revolutionary: genetic info is
the bearer of variation, not
the organism; only “vehicle”
Separation: growth/reproduct.
“Lamarck finally dead”
Cf. Dawkins’ Selfish Gene !!
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4.8 Gregor Mendel (1822-1884) The first robust theory of
inheritance
OSA monk and abbot in Brno (CZ). Experiments with peas etc.,
publication 1865 in Austrian Journal, no reception. Only from 1900!
Question in those times: Does evolution go uniformly or in jumps?
Darwin: (Newton’s ideal! Natura non facit saltus!): uniformly
Huxley, Galton: undirected, small mutations / variations
BUT: such undirected small changes can cause no big changes, since
statistics equalizes their effect. Statistical samples tend to average.
Hence, there must be other factors, Mutation must be more important.
Mendel’s method: reduction to only few (Y/N, not gradual) features,
quantification (counting)
Experiments with crossing of peas and beans; features: white/lilac
flowers; white/red/pink flowers, smooth/wrinkled seed.
Result: Mendel’s rules
4.8 Gregor Mendel (1822-1884) The first robust theory of inheritance
Mendel’s first law (+ some more)
Presumptions: unmixable, discrete factors of inheritance
mutation more important than selection,
bigger jumps are possible
But: biometry, statistics show continuous slow change. How can this
possibly be harmonized? “Great crisis of Darwinism” in early 20th century!
4.9 The Molecular Revolution in Evolutionary Biology
End of 19th century: discovery of chromosomes in cell nucleus
1903/04 Sutton/Boveri: genetic info stored in chromosomes
1910 Johannsen: Terminology “Genotype” (inner constitution, info)
“Phenotype” (appearance);
Genotype  Phenotype!
The genotype is inherited, not directly the features!!
After 1909 Drosophila experiments (quick reproduction, only 4x2 chromos.)
Beginning of localisation of genetic info on chromosomes (chemistry still
unknown till 1953!)
Insights:
- some features controlled by more than one gene
- there are interactions between genes
- one gene can influence more than one feature
HENCE: 1:1-matching “genes  features” false since early 20th century!
“genetic blueprint” metaphor likewise wrong (still it is around…)
4.9 The Molecular Revolution in Evolutionary Biology
1953
Watson/Crick: Discovery of double-helix structure of
desoxyribonucleic acid (DNA)
Since mid-1960: Mechanisms of gene expression (DNA –
RNA – proteine synthesis) begin to be clarified
“Human genome project” 1990-2003
Mind the correct way of speaking:
“Sequencing the genome”.
(Not: “decoding the genetic code”
– fallback to blueprint model!)
4.10 The “Modern Synthesis” (1920s, 1930s onwards)
Darwinism had no undisturbed victorious career; no uniform development
of post-Darwinist biology. Especially Mendel’s genetic discoveries
caused worries: quick changes, “either/or” are possible. Mutation is
more important!
Darwin’s intuition: small, incremental steps, selection is more important
“The great crisis of Darwinism” / “Eclipse of Darwinism” (J.Huxley 1942)
Late 19th/ early 20th century: all 5 tenets of Darwin come under doubt,
many biologists step back to older theories, partly speculative.
Extension of population genetics (Ronald Fisher, Sewall Wright, John B. S.
Haldane): Complex mathematical models to combine Mendel & Darwin
Some ideas from population genetics:
• On genotype level Mendelian jumps, on phenotype level only small
Darwinian changes: since features often depend on many genes!
• Population (not individuals) as the unit of evolution, statistics equalize:
in some individuals Mendelian jumps, in population slow Darwinian shift
• The smaller a population, the easier are big jumps possible.
4.10 The “Modern Synthesis” %
Theodosius Dobzhansky, Ernst Mayr and others:
“The Modern Synthesis”, “Synthetic Biology of Evolution”…
…connects: Darwinian core idea (stepwise evolution, selection)
Mendelian genetics
Population genetics
Biometry
Microbiology
Biochemistry
Behavioral science
Paleontology
Geology
etc.
4.11 Some special ingredients of the Modern Synthesis
Genetic drift / bottleneck / founder effect
(A non-adaptive effect,
against pan-selectionism!)
Punctuated equilibrium (Eldredge/Gould)
Various explanations of stages of stasis
and rapid evolutionary change; allopatric
origin of species (related with genetic drift)
Neutralism (Kimura): many big changes in DNA come and go,
without being tested by selection, neutral changes possible
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4.11 Some special ingredients of the Modern Synthesis %
Cooperation between genes; “Regulator genes”, governing the
expression of other genes, “genetic switches”. E.g. Hox genes, regulate
development of legs, antennas etc.
 mutations in such genes may have big effects!
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“Evo-Devo” (Evolutionary developmental biology):
similarities in the genotype are astonishingly high across species, but
phenotypes differ dramatically!
Hence: genes in themselves are not so important
Hence: difference must lie in the expression of the genes,
development of the organism, regulator genes etc.
Evolutionary biology in the past took adult organism (and populations
out of them) as subject to natural selection,
EvoDevo takes the whole process/cycle of development of an
organism as the subject of natural selection.
5. Evolution: Theory-structures
and concepts
5.1 Theory-structure of EB
Physics, chemistry etc.: law-like explanations, able to prediction
false predictions a part of falsification
Evolutionary biology admits of (almost) no interesting predictions
Herschel: “un-scientific”, mere statistical relations
(young) Popper: unfalsifiable tenets like “the survival of the fittest”, circular.
Partial answer:
(1) Parts of explanations admit of predictions (cell level etc.)
Some few experiments with bacteria admit of prediction even of
“direction of evolution” on macro-level: in lactose solution, bacteria with
mutation develop genes to process lactose
(2) Why decreeing that all “scientific” explanation must resemble physics?
5.2 Is EB a “science”?
Not a science like physics; combination of natural & historical disc.
Rather: a scientific research program, uniting many disciplines
Criteria by Philip Kitcher (The Advancement of Science, 1993)
A scientific practice…
• Investigates an accepted domain of objects
• Investigates accepted problems and questions
• Has a non-natural technical terminology
• Has commonly shared convictions at its basis
• Applies accepted means and methods
• Has accepted standards on aim and success of the investigations
• Has accepted standards how to accepts results from other sciences
• Is part of a social network
Evolution biology scores excellently under most criteria!
5.3 The bearers / objects of evolution
Individuals / organisms?
Species?
Populations?
Genetic information?
Life-cycles?
…different metaphysical views on objects of biology!
5.4 What are the traits / characteristics / features tested by evolution?
a) only bodily features (shape, food tolerances, …) or also behavior?
Dawkins: “the extended phenotype” (including behavior) is being tested!
b) “Adaptive” traits (with a success story) – “maladaptive” traits – “by-products”
c) Is every feature adaptive?  Panselectionism. (But: what is a feature??)
d) Beware of a frequent misunderstanding concerning “success story of trait”:
- not the trait makes its success story (the trait is not there from beginning!)
- rather: ex post, we see a success story of the trait and its previous traits
(evolution does “bricolage” with available traits!). No “trait essentialism”
5.5 Misunderstandings
“Survival of the fittest”: - Can be incremental; need not be perfect
- need not be “the strongest/biggest/…”
“Struggle for life”:
- is not intra-population struggle
- need not be fight with similar species
- just general struggle with the ecological
conditions: food, climate, safety, nesting-places…
5.6 “Genes”
(… an unsettled debate! “by the genes” is no explanation!)
“place on the chromosome”? – surely to imprecise
“sequence on the DNA” (concrete gene)? – things are more complicated:
are “regulated /switched-on” genes really genes? Coding/non-coding
DNA? Some DNA sequences are “read” more than once, some correspond to more than one proteine? Beginning/end sometimes unclear, …
“whatever makes a difference in fitness” (abstract, functional gene)? – may
come close to antirealism concerning gene & genetic info.
6. “Evolution” between science
and world-view
6.1 Overview
SCIENCE:
Darwin’s (historical) Darwinism
“Darwinism”
Synthetic theory of Evolution (1940 onwards)
Current EB (“New synthesis”, “EvoDevo”, …)
CONTROVERSIAL:
Pan-Selectionism
Sociobiology
“Cultural Evolution”, “Memetics”
NON-SCIENCE:
Social Darwinism
Pop-Darwinist Slogans
6.2 Pan-Selectionism
Sometimes also: “strict neo-Darwinism”, “Darwinist orthodoxy”
(Terminology seems not to be entirely fixed)
• Thesis: natural selection is the driving force of evolution; every
feature has an “evolutionary success story” behind it
• Tendency to a deterministic account of the world and the human
being: evolutionary successful features are +/- “hard-wired”, that
includes also our mind, our reactions, etc.
• Critical evaluation: empirically unplausible in the light of modern
genetics
• Ironically: a remainder of old “perfect adaptation” ideas (natural
theology)
6.3 Sociobiology
• Extension of evolutionary explanations also to our behavior, moral
beliefs etc.
• First visions already in Darwin: “moral tribes” might be more
successful
• Example1: why is altruism evolutionary successful?
– At first glimpse: not at all. Risk your life, lose eating-time etc.
– Example “whistle-blowing” birds
– But kin-selection / group-selection (E.O. Wilson, Sociobiology 1975):
brothers/sisters have 50% same genetic info, cousins 25%, …
 saving the life of, e.g., 5 cousins by whistle-blowing (and sacrifying
own life!) increases the survival of own genetic info! 125 - 100= +25%
• Example 2: why are moral norms evolutionary useful?
An economic way to secure cooperation of group members,
internal/mental control instead of expensive external forces
• Critical evaluation: Empirically: unclear evidence
• Manifold cultural shapings of behavior, limit natural/cultural unclear
• Sociobiol. is no exclusive explanation (“altruism is nothing but xy…”)
6.4 “Cultural evolution”, “memetics”
1976 Richard Dawkins, The Selfish Gene (and in later books)
1995 Daniel Dennett, Darwin’s Dangerous Idea
• Basic idea: behavioral and cultural practices are passed on by
imitation, they can be seen as items of “cultural information”:
“memes”. Such memes undergo competition and selection, some
do propagate, some do not
• Examples: termite-poking of chimpanzee tribes; language, use of
fire, wheel, wall-graffiti, literary figures, cooking recipes, religion,
product designs, business ideas…
• Critical evaluation: Suggestive examples…
But huge differences between genes and memes:
- genes mutate at random, memes often intentionally
- genes from distant branches of evolution non mixable, memes are
- memes are inherited in Lamarckist ways, individual inventions
In sum: misleading metaphor, parasitic on good image of biology.
Even dangerous when mixed with ideas of neo-liberalism
6.5 Social Darwinism
Label from 19th century, roots rather in Thomas Malthus and Herbert
Spencer than in Darwin.
Basic ideas:
(1) Evolutionary explains (and predicts) social facts
(2) Evolutionary biology is not only descriptive (what is
the case?), but also normative (what should we do?)
(3) Evolution is progress
(4) There are “good” and “bad” genetic information-bits (for
that progress!)
(5) Progress should not be retarded, “bad” genetic info
should be suppressed (handicapped, lower races, …)
Usually: rivalry of all against all (people in a society, nations / nations,
…), misunderstanding of “struggle for life”
Notabene: NS ideology was not closely connected with Darwin. Racism!
6.5 Social Darwinism
Critical evaluation:
(1) Is/ought fallacy, description / normativity fallacy / genetic fallacy
(2) “Biological basis”of Social Darwinism is dubious and rather Lamarckist:
Evolution is progress.
But: progress/regress are not biological categories at all
(3) It depends on the environment which forms are “progressive / more
successful” (small and undemanding animals might be most successful!)
I.e., social Darwinism rests on some aesthetic ideals of what is healthy,
strong, progressive etc.
(4) Even if we could create a “perfect natural world”, this does not guarantee
a pleasant, humane culture. False genetic determinism, nature does not
determine culture.
6.6 Some pop-Darwinist slogans
“Nature and Evolution are nothing else but a huge process of
chance and random”
– BIOLOGICALLY FALSE, at least selection is not random.
“Darwinism means that mutation and natural selection explain
every feature.”
– BIOLOGICALLY MOST PROBABLY FALSE, only most narrow-minded
pan-selectionists would deny other evolutionary effects
“Cosmic evolution”: “There is one big evolutionary process from
Big Bang to human culture.”
– CONCEPTUAL NONSENSE. (1) Not every agglomeration and
development process (as in the early universe) is also an evolution
process. There is no multiplication, mutation, inheritance, and selection
for protons, galaxies, stars etc. Over-extension of a biological metaphor.
(2) On cultural evolution, see 6.4.
%
6.6 Some pop-Darwinist slogans %
“Society and economy work according to evolutionary laws.”
– SEE 6.4 above!
“Science (like biology) consists of falsifiable claims only, worldviews are irrational and subjective.”
– FALSE FROM THE VIEWPOINT OF PHIL. OF SCIENCE. (1) Too
narrow concept of “science”
(2) Background assumptions are even at work in the sciences: see
Kuhn’s paradigms, Lakatos’ “hard cores” of research programs. Border to
world-views fuzzy; world-views contain rational structures, can be
more/less plausible, and rationally discussable. See Popper: there are
genuine philosophical problems, beyond science.
6.7 Biology and Religion: On “Creationism”, “Intelligent Design” etc.
A bit of history
USA a country of small religious groups, partly literal reading of the Bible
About one half of the population has serious doubts about evolution
Empirical fundament: unclear spots in evolution, cosmic fine tuning
Spectrum:
• Short-time (Young-earth) creationism
6 days, about 6000 yrs ago
• Long-time creationism (special creationism) successive intervention
• “Intelligent Design” design-plans, to solve irreducible complexity
• “Theistic Evolution” (Vatican II; God as 1st cause carries 2nd causes)
• Deism
• Atheism, metaphysical naturalism
Wealthy think-tanks, www.discovery.org etc., disinformation, wedge
6.7 Biology and Religion: On “Creationism”, “Intelligent Design” etc.
Objections to ID
• Unclear ontology of “design plan”, at odds with usual scientific ontology
• Selective evidence, focused on explanatory gaps and failures of EB
• Some irreducible complexities are reducible; regulator-genes etc. may
explain complexities
• “Filling-the-gap-theology”: every new biological discovery makes God
more irrelevant, theology on constant retreat
• ID proves only world-constructor (demiurg), not creator
• Why a single God behind the 1000’s of appearances of ID? Tacit
background theology smuggled in.
• Problem of evil radicalized: source of bad design, senseless design?
• In sum: neither necessary nor fruitful for the Christian.
• (Due!) criticism of reductionism and ideology should not turn into (undue)
pseudo-scientific blends of theology and biology.
7. Summary
•
•
•
•
•
•
Aristotle inaugurated a vision of biology with the species in focus,
and a teleological view at the world – yet, without external design.
The raise of modern evolutionary thought began before Darwin and
was based on empirical findings as well as on speculative ideas.
Darwin and Wallace developed the first coherent, large-scope theory
with a broad empirical basis (still with many blind spots).
The basic ideas of Darwin are still topical in the core of current EB.
However, EB can’t be reduced to “mutation and selection”.
Current EB is a research program with many open questions,
especially about the impact of natural selection. Central concepts
like “gene” admit of different readings.
This is one reason why EB has a strong affinity to be reduced to an
ideology, more than other sciences. Another reason is the wide
scope of EB, from the explanation of shape to behavior.
ID is a dubious blend of theology and biology which appears neither
necessary nor useful for the theologian.
8. Repetition questions
1.
2.
3.
4.
5.
6.
How does Aristotle’s conception of science differ from Plato’s?
Name 4 of Aristotle’s biological writings and their (rough) content.
How does Aristotle’s method in biology resemble/differ from today?
What type of discipline is an episteme, what a historia?
Why did we describe Aristotle’s biology as „teleology without design“?
Sketch Empedocles’s explanation of the origins of life and Aristotle’s
counter-argument.
7. Aristotle’s doctrine of the stability of species (what is it?) is said to have
prevented evolutionary ideas for centuries. But are there any traces of
variability of species in Aristotle?
8. How did Aristotle describe the development of an embryo?
9. What is preformationism?
10. What is procreationism?
11. What was new about Linné’s taxonomy system? What are its limits? Was he
an Aristotelian?
12. What other inventions did he make which are still important for biology?
13. Sketch Buffon’s anti-Linnéan position.
14. What was the Paris Academy Dispute 1831 ultimately about? (Don’t just say
“idealist versus evolutionary morphology”, but explain the issue!)
15. What are “homologous” organs, what are “analogous” ones?
16. Explain some of the basic intuitions of Romanticist biologists, and name
some important persons.
17. Why can we say that Lamarck presented the first evolution theory? Only under
what conditions should something be called an evolution theory?
18. What does crucially distinguish “Lamarckism” from standard evolutionary
biology?
19. How did Lamarck explain the change of organisms in the course of time?
20. Name some thinkers and researchers who influenced Darwin!
21. How did Malthus change Darwin’s thought?
22. Why is Darwin’s theory of natural selection no theory of perfect adaptation?
23. What is sympatric, what allopatric origin of new species?
24. How did Ernst Mayr summarize classical Darwinism?
25. Sketch Darwin’s “gemmulae” theory. What was it good for, what was it
supposed to explain?
26. List some open problems in Darwin.
27. Why are Haeckel’s tree-diagrams suggestive in a false direction?
28. What does his “biogenetic fundamental law” say?
29. Describe the separation of genetic information from the organism in Galton,
Weismann and Dawkins. In what are stirp, germ plasm and selfish gene similar?
30. What new point of view dis Galton bring into biology? Why does this bring
a turn away from Aristotelian ideas?
31. Why was the “Weismann barrier” seen as a death-blow to Lamarckism?
32. Why did Mendel’s discoveries shake the Darwinism of his time? What was
the worrisome problem?
33. Sketch some main steps in the discovery of genetic information.
34. Why is “we can today decode the genetic code” a problematic way of
speaking?
35. Why can population genetics perhaps unite Darwinist and Mendelian ideas?
36. What does “pan-selectionism” claim?
37. Why is the (empirically backed!) idea of genetic drift an argument against
pan-selectionism?
38. Try to describe some basic ideas of EvoDevo. Why is EvoDevo a remedy
against the misconception of a “genetic blueprint”?
39. How do evolutionary explanations differ from physical explanations?
40. Why has evolutionary biology a special structure, different from other
natural sciences?
41. What units/bearers of evolution were proposed in the history of biology?
42. Why is it misguided to say “feature F had an evolutionary success story”?
43. What did Darwin mean by “struggle for life”?
44. Sketch different notions of a “gene”.
45. How would socio-biologists explain that altruism is sometimes evolutionary
successful, even if it goes to sacrificing one’s life?
46. What is a “meme”? Why is “cultural evolution” a non-starter?
47. Describe the mistakes of “Social Darwinism”.
48. Why is “Intelligent Design” not a wise choice for theologians?
GOOD LUCK FOR THE EXAM!