Image removed due to copyright: Cartoon depicting “Pre-man,
Man, Postman” can be obtained from cartoonstock.com
Image removed due to copyright: Cartoon of ‘human
evolution’ can be obtained from toondoo.com
Einstein & Darwin: Different approaches
Biggest success of an almost
exclusively empirical approach.
Biggest success of an almost
exclusively theoretical approach.
Images from Wikipedia in public domain.
Darwin’s hypothesis
1. The Earth has undergone and is continuing to
undergo systematic change, which means that
life must change in order to survive.
2. Nature provides an unlimited supply of
unsolicited, fortuitous, and hereditary
novelties as a result of sexual selection.
3. The fertility of nature leads to an inevitable
struggle for existence.
So, it all starts with the pesky fossil
record (because the fossil record
records changes in biology over TIME)
There was an assumption in western Europe
that the living world was an unaltered replica
of the one God created. No species were lost
or altered. Consequently, educated people
downplayed the significance of the similarities
between fossils and living organisms.
The pesky fossil record
Ultimately, the biological origin of fossils was
recognized. Then, it was assumed that the
fossils were destroyed in a flood (Noah’s
flood).
When it became clear that there were multiple
extinction events, it was assumed that there
were multiple floods.
I’m pesky
I’m a trilobite
(the state fossil of
Wisconsin) and
thoroughly
extinct.
Image from Wikipedia, created by Moussa Direct Ltd.
Yet one more problem
While some fossils go extinct at particular times in
the geological record, other similar organisms live
through these extinction events.
For example, a chap named Robert Chambers noted that a Miocene badger cannot
be distinguished from a present-day badger.
(removed
image of
badger
skeleton)
Image from Wikipedia.
Image from Wikipedia
The Argument from Design
Naturalists in the 1700s were increasingly struck by the
fitness and efficiency of living things. It seemed that
feathers, fins, hearts, lungs, and eyes were perfect for
the functions they served. Thus, they must have been
designed.
Here was, apparently, a rational argument in favor of
God’s existence. It wasn’t necessary to rely on Biblical
faith, since scientific facts required an intelligent
designer.
This is the concept of Natural Theology.
Back to Hume, again.
David Hume, in the 1700s, counters this argument
in his usual, extremely thorough way.
Logic being, after all,
inescapable.
Hume argued against design with
counter examples drawn from
monstrosity, imperfect forms of
testimony, and probability.
Image courtesy of the Web Gallery of Art.
The breakthrough: First thoughts of
Evolution
Georges-Louis Leclerc, Comte de
Buffon was a naturalist,
mathematician and biologist in
1700s France.
Buffon challenges the 200+ year old
doctrine of fixed species.
His major work is the Histoire
Naturelle, Générale et Particulière.
Compte G.L.L. de Buffon
Image from Musée Buffon à Montbard
An aside: What is a species?
A species is defined as a group
of organisms capable of
interbreeding and producing
fertile offspring.
Or, King Phillip Came Over From
Germany Swimming.
Image credit: Peter Halasz
Buffon recognized that
animals multiply faster than
the available food supply.
This situation inevitably lead
to a deadly competition for
existence.
The implication is that
species are not fixed (that is,
a species can cease to exist),
and that there could be
change in the makeup of a
species.
Image from De humani corporis fabrica (1543)
Early thoughts of Evolution
Buffon’s idea is expanded on by Lamarck, who was devoted to
the traditional doctrine of the Great Chain of Being.
Nature consists of a graded series
of natural types, arranged in
order from the simplest and
microscopic and the largest and
most complicated
J.B.A.P de Monet Lamarck (aka Lamarck)
Source: Galerie des naturalistes de J. Pizzetta, Ed. Hennuyer, 1893
Here is the gist: Since God created the world, nature was
endlessly on the move, as all creatures were struggling to
become as humans. Since creatures are always getting more
complicated, there has to be spontaneous generation of new
forms. Think about it in terms of an escalator.
There were two natural forces
that competed to do this:
1. The inherent drive to
complexity: Living matter had
a inherent ambition to get
bigger and better, so each
creature was drawn to a higher
stage of development
Image source: Gordon Joly
2. The shaping power of the environment: The natural
habits of a creature would inevitably lead to modification
of its anatomical structure. For instance, as long as a
giraffe kept reaching for higher trees, its neck would keep
getting longer. Further, a longer neck would be passed on
to the next generation.
In other words,
characteristics of a
parent (such as
muscularity) are
acquired by offspring
Lamarck
Source: Galerie des naturalistes de J.
Pizzetta, Ed. Hennuyer, 1893
Image from Safari Science
Early thoughts of Evolution
This idea is embraced by, among
others, by Erasmus Darwin (the
grandfather of Charles) who
suggests a theory of biological
transformation.
Image from Wikipedia.com
Erasmus Darwin
Evolution is often associated with a
single name: Darwin
I also like
barnacles.
Image from Wikipedia.
Charles Darwin –
probably more than
any scientist – singlehandedly collects the
relevant data, comes
up with the concept,
anticipates the
problems (and states
them), and publishes
it.
Which, finally, brings us to the 1830s, an era with serious mutton chops (a type of
facial hair pattern for men).
Young Charles was a famously lackluster
student, as he would rather go hunting
than study. He, obviously, was from a well
educated and wealthy family. He failed at
medical school (he didn’t really try) and at
seminary.
In fairness, he seemed to deal well with
biology and geology classes.
A friend named Herschel knew of an
opportunity as a companion (and
collector) for a voyage on the HMS Beagle,
captained by on Fitzroy.
Image by George Richmond
It turns out that Victorian England was so classist, that
Captains were not allowed to interact with their crew
during voyages. So, Fitzroy needed someone to dine with
and converse with on their trip.
I like your nose.
Author: Samuel Lane under educational reuse rationale
Yes, unbelievably, Fitzroy was an adherer to the
fashionable pseudoscience of physiognomy, the
idea that the shape of the nose could tell about
the character of a person.
Captain Fitzroy
And thus begins what must be one of the most intellectually
uncomfortable multi-year voyages (and there is plenty of competition
for this award). On the one hand, a classist, pro-slavery, and
intellectually rigid captain ingrained in the barbarity of the English Navy.
On the other, a freethinking, anti-slavery, and intellectually curious
naturalist.
What they argued most over was slavery, which Fitzroy regarded as the
natural order of things.
Author: Samuel Lane
Author: Samuel Lane under educational reuse rationale
On the bright side, it certainly is a major impetus for
spawning a whole series characters in action dramas.
(Image from
Master and
Commander)
Image from NBC Television
Video
http://www.pbs.org/wgbh/evolution/library/02/
2/l_022_04.html
Image from Oxford University Museum of Natural History
Image from A Naturalist’s Voyage Round the World
Watercolor by Conrad Martens
5 years on the HMS Beagle
Darwin brought a copy of Lyell’s Principles of Geology. Lyell was a major
proponent of “uniformitarianism” (which you may or may not remember
from the Oreskes readings). Uniformitarian was the then-controversial idea
that events that occurred in the Earth’s past can be seen acting today. The
alternative was Catastrophism (The Earth was formed only by short-lived
and violent events), which Darwin had earlier subscribed to.
Source: National Institutes of Health
Image from Lyell’s Principles of Geology
This book is significant, because Darwin is going to
propose something very similar for biological systems.
Charles Lyell
But, the stop that defines the trip, from a scientific point of
view, is South America and the Galapagos Islands (and the
finches).
Here he made three biological
observations that made it difficult
to accept the immutability of
species.
From Darwin on Volcanic Islands
From On the Origin of Species
Darwin’s observations
1. Succession of type
Darwin was struck by the resemblance of certain types of
fossil armadillos and the living species.
Image from traveljournal.net
Image from birdphotos.com
Darwin’s observations
2. Representative types
Darwin noted that the resemblance between historical successors
was mirrored by a corresponding similarity between geographical
successors. Darwin noticed that one type of flightless birds on
the South American pampas gradually became less prevalent and
by another type of flightless bird became more prevalent. The
idea he had was that populations migrated in opposite direction,
and the two types had been so widely separated that they could
no longer interbreed.
Image source: Flickr
Image by Nevit Dimlen
Darwin’s three observational types
3. The Evidence of Ocean Islands
1. Darwin visited both the Cape Verde Islands (off Africa) and
the Galapagos Islands (off South America). The design
argument would lead one to expect that all islands types
would resemble one another since God created them for the
same physical conditions. Darwin was surprised to notice that
the resemblence was stronger between the Cape Verde Islands
and Africa.
2. In the Galapagos Islands, Darwin noted that each of the
islands had a distinct population of lizards and birds, despite
the nearly identical environmental conditions on the different
islands. These are Darwin’s finches.
Source: Public Library of Science
Source: Alan Root—Bruce Coleman Inc.
On board of the boring HMS Beagle
I’m glad I came along on the
trip.
Source: National Institutes of Health
Similar to Galileo’s house arrest,
being aboard the HMS Beagle
allows Darwin to think hard a
biological species.
In particular, if the Earth could
undergo such far-reaching changes
as Lyell suggested, it wasn’t
unreasonable to assume that life
had undergone a a comparable
transformation. If not, the living
creatures would be poorly
adapted to a changing Earth and
eventually cease to exist.
When a slightly older Darwin returns to England in 1936, he finds out that he is
something of a celebrity, because of the samples that he has sent back.
I gotta say, things are going pretty well.
He publishes a travel book – The Voyage
of the Beagle – which becomes a best
seller.
He also wrote books on the Geology of
South America and Formation of Coral
Reefs, and becomes a secretary at the
Geological Society (earning him the
friendship and respect of Charles Lyell,
T.H. Huxley, and biologist J.D. Hooker).
And, he gets married to his first cousin,
Emma Wedgewood (of Wedgewood
pottery fame).
From The Life, Letters, and Labours of Francis Galton
In the light of this deduction, my theory
recognizes that the continued existence of life on
Earth can only be explained on the assumption
that the species outmoded by geological change
were replaced by new, freshly-adapted ones
Author: Samuel Lane
Darwin comes up with 2 hypotheses to explain the fact that there
are living organisms and that new fossils show up in the fossil
record: 1) Species are specially created to make up for the loss due
to extinction; or 2) They’ve evolved from their outdated
predecessors.
He rejects the 1st option. By the middle of 1837, he is convinced
that life has “evolved” and the emergence of new species was the
result of “descent with modification”.
Source: Galerie des naturalistes de J. Pizzetta, Ed. Hennuyer, 1893
Darwin rejects Lamarck’s idea of
spontaneous generation, because he
realized that evolution wasn’t a single line
of descent.
J.B.A.P. “Elevator” Lamarck
Instead, Darwin comes up with an
image of a tree, which he puts in his
notebook.
Source: Cambridge University Library
http://www.pbs.org/wgbh/evolution/library/02/
1/l_021_01.html
Darwin, in 1938, picks up a book by Thomas Malthus
“On Population”.
Thomas Malthus was a
conservative schoolmaster
economist, whose main purpose
in publishing a book on
population was to argue against
the indiscrimate use of social
welfare.
Nature is so fecund that any careless
attempt to alleviate poverty will
encourage unsupportable increases in
population and only exacerbate the
suffering it is designed to relieve.
Image from Wikipedia
While Darwin was inherently a reformer, and thus
opposed to Malthus’ laissez-faire politics, the
mathematical argument was sound.
Populations increase by geometrically, and can be
predicted by an exponential curve. The resources will
not be able to keep up. At some point, there will be a
serious struggle for existence.
(Removed graph of
Malthus’ basic theory,
can be found here.)
From Lewis Historical Society
And lest you need to be convinced of the enormity of the problem, the human population
has grown by exponential growth.
World Population Growth
Image from Wikipedia
Be worried. Be very worried.
Video
http://www.pbs.org/wgbh/evolution/library/02/
5/l_025_01.html
Darwin has his idea “figured out” by 1842, but then writes
a 250 page version in 1844.
And then, what happens??
Barnacles.
Yippee!
Source: Marine Climate Change Impacts Partnership
From The Life, Letters, and Labours of Francis Galton
Source: Marine Climate Change Impacts Partnership
Yea! Our day in the sun (oops, wait,
that sucks if you are a barnacle).
Yep, barnacles. Darwin doesn’t do anything about
publishing this idea for the next 20 years. He takes a
decade to study and write up research on barnacles.
He also spends a lot of time finding out about pigeon and
horse breeders. This experimental “artificial selection”
will ultimately act as a counterpart to his natural
observation “natural selection”, presumably as
experimentation is seen as more scientific.
Who knows what would have happened if Alfred Wallace had not
come up with the same idea. Wallace, a naturalist like Darwin
(arguably Wallace was more accomplished in collecting data in the
field), had basically come up with the same idea.
Given that it was Victorian England, Wallace writes to – of all
people - Darwin to explain his idea.
Species change through
time as a result of their
environment.
And, I like the climate
better in Indonesia.
Source: Alfred Russel Wallace: My Life
This communication puts Darwin, who is extremely moral, in a
very bad position. What should he do? He confides about the
situation with his friends Huxley and Hooker.
Ultimately, Huxley and Hooker came up with a compromise:
Darwin will present the idea, with Russell and himself as coauthors.
Publish!
And, his friends also had some
advice.
Author: Thomas Herbert Maguire
Source: Case Western Reserve University
And, in this way, The Origin of the
Species was published in 1859.
It sold out the first
day: It was a
commercial
success.
It also immediately
drew criticism.
Source: Encyclopedia Brittanica
I might be the only person who looks
better in a cartoon than in real life
Source: Desmond A. 1982
Professional jealousy influenced the
detestable (for other reasons,
including the tormenting of Gideon
Mandel and Mary Anning) Richard
Owen into opposing evolution.
Published in Vanity Fair, source
But, by far and away, the bigger problem was
social and religious. One of the earliest
opponents was Bishop Wilberforce, who
challenged Darwin to a debate in a scientific
forum. Darwin actively disliked conflict, but
Huxley and Hooker agreed to represent his
viewpoint.
Harumph
Samuel Wilberforce
First published in The Life and Letters of Lewis Carroll
Famously, it got kind of ugly (especially in Victorian England)
‘Is it on your grandfather's
or grandmother's side that
you claim descent from the
apes?’
`I would rather be descended
from an ape than someone who
used his eminence to propound
uninformed twaddle’
Source: Case Western Reserve University
First published in The Life and Letters of Lewis Carroll
Huxley
Image from funstuffonly.com
Samuel
Wilberforce
OK, here is the scientific lowdown.
Original image by Marv Newland
Darwin’s hypothesis
1. The Earth has undergone and is continuing to
undergo systematic change, which means that
life must change in order to survive.
2. Nature provides an unlimited supply of
unsolicited, fortuitous, and hereditary
novelties as a result of sexual selection.
3. The fertility of nature leads to an inevitable
struggle for existence.
There were four scientific objections to
Darwin’s Theory of Evolution
1. Age of the Earth (Not enough time for natural
selection to happen)
2. Lack of complete, gradual changes in the fossil
record
3. What is the cause for earlier forms of complex
organs (e.g., the eye) to evolve
4. Why aren’t positive mutations “swamped”
when a single individual with that mutation
has to interbreed with an entire population
We’ll take these one at a time.
Age of the Earth
Lord Kelvin was arguing with the geologists
about the age of the Earth. For Darwin’s idea
to work, the Earth would have to be very, very
old (100s of millions of years).
As we’ve already seen, the geologists turned out
to be correct, but this was a major problem at
the time (and remains a problem for those
who resist evolution for religious reasons).
Lack of transitional forms in the fossil
record
Because Darwin was following from Lyell’s
uniformitarianism, he suggested that the
change of one species becoming another
species must take place gradually. He is
partially correct, in that many transitional
fossils have now been found. He is incorrect
that changes all happen slowly, as there are
periods of fast changes in the fossil record.
Why would complex organs (e.g., the
eye) evolve
Zoologist H. St. George Mivart argued that
although natural selection might account for
the success of well-established adaptions, it
couldn’t explain the initial stages of
development.
Darwin countered, correctly, that an organ can
be just as profitable in its early stages, but not
necessarily in the same ways.
Image source: Nevit Dilmen
For instance, think about wings. Small wings could be
used to gliding, running faster (biological airfoils, if you
will), or just scaring the heck out of some other critter.
Darwin thought that it was mystical nonsense to
suppose a some trait (e.g., a feather) emerged in order
to realize the remote possibilities of some use (e.g.,
flight).
The inheritance problem
Scottish engineer Fleming Jenkin pointed out
that a positive mutation would be swamped
out when the fortunate individual interbred
with “normal” members of a population.
This was a serious problem, but it wasn’t going
to be resolved until someone (hello Gregor
Mendel!) figured out how inheritance worked.
Which, leads to Gregor Mendel
Source: US National Library of Medicine
From glogster.edu
Original parents only produce tall plants.
One can observe short plants in the next
generation.
From Thinkquest, under educational reuse rationale
From a typepad blog
From U.S. National Library of Medicine
Problems with the theory
Peacocks
http://www.pbs.org/wgbh/evolution/library/01/
6/l_016_09.html
And another crazy example of sexual
selection
Lyre birds (from Australia)
Author: John William Lewin
http://www.youtube.com/watch?v=VjE0Kdfos4Y
Image source: Wikipedia
What happened?
In Europe and North America, evolution is accepted as a
law, but the theory of natural selection was generally
rejected in favor of Lamarck’s mechanisms.
By the end of the century, only two prominent biologists
remained unswervingly loyal to natural selection:
Alfred Wallace (England) and August Weisenmann
(Germany). That is, however, all that were needed.
*For the record, Wallace was always very complimentary
of Darwin, and never felt slighted