Transcript PPT - 2 - Biologists before Darwin

What the Bible Says
Genesis 1:11-12: And God said, Let the earth bring forth grass,
the herb yielding seed, and the fruit tree yielding fruit after his
kind, whose seed is in itself, upon the earth: and it was so.
And the earth brought forth grass, and herb yielding seed
after his kind, and the tree yielding fruit, whose seed was in
itself, after his kind: and God saw that it was good.
Genesis 1:24-25: And God said, Let the earth bring forth the
living creature after his kind, cattle, and creeping thing, and
beast of the earth after his kind: and it was so.
And God made the beast of the earth after his kind, and
cattle after their kind, and every thing that creepeth upon the
earth after his kind: and God saw that it was good.
Of all clean birds ye shall eat.
But these are they of which ye shall not eat:
The eagle, and the ossifrage, and the ospray,
And the glede, and the kite, and the vulture after his kind,
And every raven after his kind,
And the owl, and the night hawk, and the cuckow, and the
hawk after his kind,
The little owl, and the great owl, and the swan,
And the pelican, and the gier eagle, and the cormorant,
And the stork, and the heron after her kind, and the lapwing,
and the bat.
Deuteronomy 14:11-18, King James Version
Plato (427 – 347 B.C.E.)
Plato believed that the world is a
mirage, that the only things that
really exist are immutable
Forms or Ideas, and that objects
in the real world are just
evanescent shadows of these
Forms.
In Book 7 of The Republic Plato explains this concept
using the allegory of a cave with prisoners watching
shadows on a wall producing by firelight shining over
the real objects.
Essentialism
Essentialism, based on Plato’s concept of Forms,
dominated Western thought for over 2000 years and
impeded progress in biology. There was an ideal
form of each animal and plant; individuals varied a
little from the ideal form because they were imperfect
copies, but the ideal form was “divine, deathless,
intelligible, uniform, indissoluble, always the same as
itself.” (Plato’s Phaedo)
This concept was antithetical to the concept of
evolution.
Aristotle and the Scala
Naturae
Aristotle (384 – 322 B.C.E.) did
believe in reality, and
developed a “natural
philosophy” that included
many of today’s sciences,
particularly physics and
biology.
He visualized nature as a ladder
(the scala naturae) with earth
at the bottom, then plants, then
animals, then humans.
Plato and Aristotle in
Raphael’s The School of
Athens
Scala Naturae
The Great Chain of Being
Christianity added angels and
God to the ladder, the “great
chain of being,” with earth and
minerals at the bottom, then
plants, animals, humans,
angels, and God in
progressively higher levels.
Some levels were subdivided
into higher and lower animals,
higher and lower humans
(peasants, aristocrats, kings),
and so forth.
A sample of Aristotle’s biological writing:
“Of birds, some take a dust-bath by rolling in dust,
some take a water-bath, and some take neither the
one bath nor the other. Birds that do not fly but keep
on the ground take the dust-bath, as for instance the
hen, the partridge, the francolin, the crested lark, the
pheasant; some of the straight-taloned birds, and
such as live on the banks of a river, in marshes, or by
the sea, take a water-bath; some birds take both the
dust-bath and the water-bath, as for instance the
pigeon and the sparrow; of the crooked-taloned birds
the greater part take neither the one bath nor the
other.” – History of Animals, Book IX, 49B.
A story by Aristotle
“A story goes that the king of Scythia had a highlybred mare, and that all her foals were splendid; that
wishing to mate the best of the young males with the
mother, he had him brought to the stall for the
purpose; that the young horse declined; that, after the
mother’s head had been concealed in a wrapper he, in
ignorance, had intercourse; and that, when
immediately afterwards the wrapper was removed and
the head of the mare was rendered visible, the young
horse ran away and hurled himself down a
precipice.” – History of Animals, Book IX, 47.
The Immutability of Species
For centuries it was believed that the different “kinds” of
animals and plants had been created exactly as they were
today, and had never changed: they were immutable.
Also, because God’s creation was perfect, no animal or
plant created by God had ever become extinct.
Evidence began accumulating in the 18th and 19th
century that there were extinct organisms; also,
immutability became suspect.
The Species Question
What is a species? How can you tell if two organisms are the same
species or different species? If two organisms can interbreed, are
they of the same species? If they can’t, are they of different species?
How can you tell if one organism is descended from the other, or
both are descended from a (recent) common ancestor?
Example of questions relating to species:
• Modern humans (Homo sapiens) and Neanderthals (Homo
neandertalis) are considered different species. Did H. neandertalis
evolve into H. sapiens or were they both descended from some
common ancestor? In either case, could or did they interbreed, and
does H. sapiens have any H. neandertalis genes?
• Wolves, jackals, coyotes, and dogs can all interbreed with one
another. Are they one species, or different species, and if the latter,
how many?
The Species Question …
Are sugar maples and red maples and Japanese maples all
members of the same species, maybe just different
varieties (whatever that means) of that species, or are they
different species?
Are Clemson Spineless okra and Red okra different
species, or just varieties in a single species (okra)? What
distinguishes species from varieties?
For centuries most botanists and zoologists felt they knew
the difference, but they didn’t always agree with one
another. Those who carefully examined the species
question usually became confused and uncertain the more
they studied it.
Different Species Concepts
Traditionally, two groups of animals or plants were regarded as
belonging to different species if they appeared to be sufficiently
different: different “types” or “kinds” of organisms. But by this
definition a monarch caterpillar and a monarch butterfly were
different species.
Today, the biological species concept is generally accepted:
“Species are groups of interbreeding natural populations that are
reproductively isolated from other such groups.” – Ernst Mayr,
What Evolution Is (2001)
Wolves, jackals and coyotes are three natural populations that could
but do not interbreed, so they are different species.
Many examples are known of “sibling species” which resemble
each other, live in the same area, but do not interbreed.
Ring Species: Larus gulls
In Europe there are two
different species of gulls
known as the herring gull
and the lesser black-backed
gull, the former living in
Norway and the latter in
Norway and the British
Isles. They do not
interbreed.
Go around the north pole
and the fact that they are
different species becomes
difficult to claim.
Two different species of gulls in
Norway: on the left, the herring
gull, and on the right, the lesser
black-backed gull.
Around the arctic there
is a “ring” in which the
Larus gulls live.
Going west from the
British Isles, the lesser
black-backed gull
slowly changes into
slightly different gulls
such as the American
herring gull, the Vega
herring gull, etc.,
finally becoming the
herring gull in
Norway!
Are these one species
of gull, or two?
The Ensatina Salamander
Around the Central Valley of California, up the mountains
a little, not down in the valley, are found a ring of Ensatina
salamanders. Any two neighboring populations of these
salamanders can and do interbreed. But on the western
side, at the south end, is the plain Ensatina eschscholtzii,
and on the eastern side, at the south end, is the large
blotched Ensatina klauberi. These two species do not
interbreed, so they appear to be different species by the
biological species concept. However, they are
morphologically identical and actually can interbreed, as if
they were a single species.
Important Biologists Before Darwin
John Ray (1627 – 1705)
Karl Linnaeus (1707 – 1778)
Comte de Buffon (1707 – 1788)
Erasmus Darwin (1731 – 1802)
Jean-Baptiste Lamarck (1744 – 1829)
Georges Cuvier (1769 – 1832)
John Ray
(1627 – 1705)
English naturalist – really the
father of English natural history.
Published important works on
plants, animals, and natural
theology.
Taught for a time at Trinity
College, Cambridge, where
Francis Willughby (1635 – 1672)
was first his pupil, later his
colleague and patron after Ray
lost his position for not
subscribing to the 1661 Act of
Uniformity.
John Ray’s Books
Catalogus plantarum Angliae (1670) catalogued English
plants, and was the basis for all later such works.
Methodus planarum nova (1682) described Ray’s method of
classifying plants, with particular emphasis on the
difference between monocotyledons and dicotyldeons
(plants germinating with one or two leaves).
Historia generalis plantarum (3 vols., 1686, 1688, 1704)
was his great taxonomic work.
The Wisdom of God Manifested in the Works of the Creation
(1691) was a very popular book espousing what came to be
known as “natural theology.”
Non-Botanical Writings by Ray and Willoughby
John Ray was fond of amassing facts about many things, as shown
by the subjects of some of his non-biological books: Collection of
English Proverbs (1670), Collection of Out-of-the-way English
Words (1674), and Collection of Curious Travels and Voyages
(1693).
Francis Willugby made a scientific study of games, which was
published in 2003 as Francis Willughby’s Book of Games. It
included a charming early description of football (the word he used),
which used “a close that has a gate at either end; the gates are
called Goals.” The ball? “They blow a strong bladder and tie the
neck of it as fast as they can, and then put it into the skin of a bull's
cod and sew it fast in. … The harder the ball is blown, the better it
flies. They used to put quicksilver into it sometimes to keep it from
lying still.”
Carl Linnaeus
Carl von Linné
(Carolus Linnaeus)
(1707 – 1778)
Swedish biologist considered
the father of modern
taxonomy.
Most of his life as a student
and professor (from 1741) was
spent at Uppsala University.
Invented the bionomial
nomenclature for organisms
(e.g., Homo sapiens,
Taraxacum officinale).
Linnaeus …
1743 – created the modern Celsius temperature scale by
fixing the melting point of ice at 0º and the boiling point of
water at 100º, instead of the other way around as Anders
Celsius had done!
Created a taxonomy consisting of three kingdoms – animal,
vegetable (plants) and mineral. His classification of plants
and (to a lesser degree) animals became widely accepted.
Kingdoms were divided into Classes, which were divided
into Orders, which were divided into Genera (singular:
genus), which were divided into Species, and then
sometimes into taxa of a lower (unnamed) rank, essentially
what we now call varieties in the case of plants.
Linnaeus …
The first edition of Linnaeus’ Systema Naturae, printed in the
Netherlands in 1735, was only 11 pages long. Linnaeus kept adding
to it and its 10th edition (1758) classified 4,400 species of animals
and 7,700 species of plants.
The bionomial nomenclature Linnaeus used had been developed in
the late 16th and early 17th century by the Swiss botanists (brothers)
Gaspard and Johann Bauhin, for some of the 6000 plants they
described in their works, but it was Linnaeus who used it consistently
and systematically.
Linnaeus’ names are still in use, denoted by “L.” after the name,
although modern genetic techniques have forced considerable
revisions in his scheme. For example, okra is Hibiscus esculentus L.
but today is called Abelmoschus esculentus; it was formerly regarded
as a species of hibiscus but now is placed in the mallow family and
only regarded as related to hibiscus.
Two portraits of Linnaeus: his wedding portrait (1739) and one
showing him in a Lapp costume (1737).
Linnaea borealis
(Twinflower)
This flower, which he
apparently first saw in
Lapland, was Linnaeus’
favorite flower, named
after him by his teacher,
Jan Frederik Gronovius.
He is seen holding it in
many of his portraits,
and he used it as his
symbol when he was
made a noble in 1757.
Borage or Starflower
Scientific classification of the Cicada-Killer Wasp
Kingdom:
Phylum:
Subphylum:
Class:
Subclass:
Infraclass:
Superorder:
Order:
Suborder:
Infraorder:
Superfamily:
Family:
Subfamily:
Tribe:
Genus:
Species:
Animalia
Arthropoda
Hexapoda
Insecta
Pterygota
Neoptera
Endopterygota
Hymenoptera
Apocrita
Aculeata
Apoidea
Crabronidae
Bembicinae
Gorytini
Sphecius (Dahlbom, 1844)
some 20 species described
Georges-Louis Leclerc
Comte de Buffon
(1701 – 1788)
French mathematician,
biologist, cosmologist,
naturalist.
Keeper of the Jardin du Roi
(now Jardin des Plantes) in
Paris.
Author of the incredible
Histoire naturelle (44
volumes), translated into
many languages.
Buffon …
Early in his career, he did important work in probability
theory, using calculus.
He solved the problem known as Buffon’s needle, the first
geometric probability problem.
If a needle of length l is dropped onto a plane with parallel
lines a distance t apart, the probability that the needle will
cross a line is 2l/tπ, which can be used to estimate π.
Needle a crosses a line,
needle b does not. Actually,
the needle can be a (plane)
noodle! (Buffon’s noodle)
Buffon …
His Histoire naturelle,
générale et particulière was
published from beginning in
1749 in 44 volumes (8 after his
death). It contained everything
known about the natural world
at the time. It is online at
www.buffon.cnrs.fr.
Right: A “giant octopus”
attacking a ship (Buffon,
1805). In fact, there exists a
giant squid but no giant
octopus, and the giant squid
does not attack ships.
Buffon …
Buffon first explained the true “greenhouse effect” in a greenhouse,
whose interior heats up when it is sunny (but not the atmospheric
greenhouse effect).
Buffon’s Law (biogeography): Buffon noted that different places,
even though they had nearly the same environment, had different
plants and animals. He attributed this to changing (evolving) after
dispersal from the place of their creation.
Darwin greatly admired Buffon. Today we realize that his views of
evolution were more correct than those of Lamarck and Cuvier,
who came after him.
Erasmus Darwin (1731 – 1802)
• Received his medical degree
at Cambridge in 1755 after
studying at Cambridge and
Edinburgh
• Became a physician at
Litchfield and later Derby
• Emphasized the power of the
mind and paid close attention
to mental as well as physical
conditions – regarded many
illnesses as having a mental
origin.
• Offered (but declined) post of
Royal Physician by George III
Erasmus Darwin (1731 – 1802)
• He “believed in the hearty joys of women, food, a little
gardening and agricultural improvement, some practical
inventions to discuss with friends, and agreeable company
in the evenings, with good books and plenty of children for
his old age.” – Janet Browne, vol. 1, page 37
• Had a large physique and became so fat that a semicircle
had to be cut into his dining table so he could dine at it and
be able to reach his food.
• Pockmarked from smallpox contracted in his early years.
Erasmus Darwin’s Progeny
• Father of at least 14 children with two wives and one
mistress.
• First wife Mary Howard (1739 – 1770) died of alcoholism, so
Darwin insisted on his family and patients never using alcohol.
She gave birth to five children, with three sons (Charles,
Erasmus, Robert) surviving.
• Fathered two illegitimate children with a young woman
(“Mrs.” Parker) who cared for the young children and became
his mistress.
• Married a widow, Elizabeth Pole (illegitimate daughter of an
aristocrat), and had seven more children by her.
Children of Erasmus Darwin and Mary Howard Darwin
Charles (1758 – 1778) – very gifted and intelligent and intended for
a medical career like his father; died at age of 19 from an infection,
possibly picked up during a postmortem examination.
Erasmus (1759 – 1799) – encouraged by his father to go into law,
but was not successful, became depressed, and committed suicide.
Robert Waring Darwin (1766 – 1848) – pushed into a medical
career by his father, who sent him to Edinburgh and constantly
sought favors on Robert’s behalf, even though Robert hated medicine
and would never have chosen it as a profession – so he resolved
never to treat his own sons that way.
Erasmus Darwin had little to do with Erasmus and Robert after
remarrying and seeing to their education – he was more interested in
his newest family.
Erasmus Darwin’s Writings
Many poems
Poems about nature and evolution:
The Economy of Vegetation
The Loves of the Plants
The Temple of Nature
Prose works for scientists:
Zoonomia (1794 – 1796)
Phytologia (1800)
The Loves of Plants
“The most delicious poem upon earth.”
“How strange it is that a man should have been
inspired with such a enthusiasm of poetry by
poring through a microscope, and peeping
through the keyholes of all the seraglios of all the
flowers in the universe!”
– Horace Walpole
Erasmus Darwin’s Take on Evolution
Life appeared spontaneously early in earth’s history
Self-generated variation and diversification led to all
modern plants and animals, including humans
No original creation or divine intervention was necessary;
nature had its own “laws of nature.” (Erasmus Darwin was
apparently an unbeliever, but never publicly denied the
existence of God.)
Mechanism of evolution: development of useful
characteristics passed on to succeeding generations –
basically, Lamarck’s theory of the inheritance of acquired
characteristics.
Organic Life beneath the shoreless waves
Was born and nurs’d in Ocean’s pearly caves;
First forms minute, unseen by spheric glass [microscope],
Move on the mud, or pierce the watery mass;
These as successive generations bloom,
New powers acquire, and larger limbs assume;
And breathing realms of fin, and feet, and wing,
Thus the tall Oak, the giant of the wood,
Which bears Britannia’s thunders on the flood;
The Whale, unmeasured monster of the plain,
The Eagle soaring in the realms of air,
Whose eye undazzled drinks the solar glare,
Imperious man, who rules the bestial crowd,
Of language, reason, and reflection proud,
With brow erect who scorns this earthy sod,
And styles himself the image of his God;
Arose from rudiments of form and sense,
An embryon point, or microscopic ens!
Jean-Baptiste Lamarck (1744 – 1829)
11th child in an impoverished
aristocratic military family in
Picardie.
A soldier for several years until
injured, after which he took up
the study of medicine.
Made important contributions to
cell theory, botany, invertebrate
zoology, and evolutionary theory.
Became a member of the French
Academy of Sciences in 1779.
Lamarck …
In 1781 Lamarck became a Royal Botanist associated with the great
Jardin du Roi (“Garden of the King”) in Paris; in 1790, during the
French Revolution, he renamed it the Jardin des Plantes (“Garden of
Plants”), by which it is still known today.
Between 1800 and 1822 he developed the first coherent evolutionary
theory. [Note: This was after he turned 56.] While believing (like
most biologists of his day) in the continual spontaneous generation
of simple forms of life, he believed in transmutation, the changing of
organisms into more complex forms in accordance with physical and
chemical principles, in a strictly materialistic manner; he referred to
this as Le pouvoir de la vie (“The force of life”).
But also, organisms evolved through L’influence des circonstances
(“The influence of the environment”), becoming adapted to their
local environment.
Lamarck’s Great Escalator of Being
Originally an essentialist, Lamarck became convinced
that molluscs changed (transmutation) over time.
Instead of a great ladder of being, Lamarck visualized a
great escalator of living things, all species constantly
moving up the ladder, becoming more complex, while
simple new beings were spontaneously generated at the
bottom. The upward movement was evolution.
The Inheritance of Acquired Characteristics
Lamarck believed that the use and disuse of characters powered
adaptation:
“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. “
Lamarck believed these characters were then inherited, a common
belief in his time; this is referred to as “soft inheritance” and was
accepted by most 19th century biologists.
Lamarck was the first to use the word “biology” in its modern
sense.
Lamarck was constantly attacked by Cuvier, who did not believe
in evolution, and so became something of a scientific pariah:
Cuvier was “in” and Lamarck was “out”.
When he died in Paris in 1829, he was very poor, his family had
to seek government assistance, and he himself was originally
buried in a lime-pit.
Today, he is highly regarded for his work and his belief in and
theorizing about evolution, although his theory of the soft
inheritance of acquired characters – which was the best theory
Darwin knew about – was disproved in the late 19th century by the
work of August Weismann, who demonstrated the difference
between somatic (body) and genetic (reproductive) cells.
Georges Cuvier
(1769 – 1832)
French naturalist and
zoologist who
compared fossil
animals with living
animals and
established the fields
of comparative
anatomy and
paleontology.
Cuvier and His Career
Cuvier was actually German, his original name Johann
Leopold Nicolaus Friedrich Kuefer, and he was educated
in Germany. He came to France as a tutor to an
aristocratic family in Normandy, and remained in France
the rest of his life. A Protestant (Lutheran), he
nevertheless was politically savvy and held many
positions at French universities and in French scientific
organizations, before, during, and after the French
Revolution and the Napoleonic Era. A real “survivor.”
His career was long and varied and dealt with both
living and fossil animals.
Cuvier’s Principle of Correlation of Parts
“Today comparative anatomy has reached such a point
of perfection that, after inspecting a single bone, one can
often determine the class, and sometimes even the genus
of the animal to which it belonged, above all if that bone
belonged to the head or the limbs. ...
“This is because the number, direction, and shape of the
bones that compose each part of an animal's body are
always in a necessary relation to all the other parts, in
such a way that – up to a point – one can infer the whole
from any one of them and vice versa.”
Cuvier’s Ideas
Cuvier’s work paved the way for the theory of evolution,
but he himself did not believe in evolution.
He believed that all present organisms had been created
exactly as they were now and had never changed, pointing
out that mummified cats and other animals in ancient
Egyptian tombs were identical to those of today.
He believed that fossils were the remains of previously
existing organisms that had become extinct through some
great catastrophe.
Glimpses of Natural Selection before Darwin
Several authors before Darwin wrote articles or
books that mentioned something like natural
selection, but none had any great impact, and none
of the authors had fully developed their theories.
William Charles Wells (1757 – 1817)
Patrick Mathew (1790 – 1864)
Edward Blyth (1810 – 1873)
William Charles Wells (1757 – 1817)
Wells was a Scottish-American physician, born in
Charleston, South Carolina, educated in Scotland, who
practiced in South Carolina.
In 1818, shortly after his death, a book entitled Two essays
… appeared which contained an appendix on An account
of a female of the white race of mankind, part of whose
skin resembles that of a negro, with some observations on
the cause of the differences in colour and form between
the white and negro races of man.
This appendix described the idea of natural selection.
Key quotation from Wells:
“[What was done for animals artificially] seems to be
done with equal efficiency, though more slowly, by nature,
in the formation of varieties of mankind, fitted for the
country which they inhabit. Of the accidental varieties of
man, which would occur among the first scattered
inhabitants, some one would be better fitted than the
others to bear the diseases of the country. This race would
multiply while the others would decrease, and as the
darkest would be the best fitted for the [African] climate,
at length [they would] become the most prevalent, if not
the only race.”
Note that Wells discussed natural selection only in
reference to humans.
Patrick Mathew (1790 – 1864)
Patrick Matthew was a prosperous Scottish
landowner and fruit farmer.
In 1831 he published a book, On Naval Timber and
Arboriculture, which described the principles of
good timber forestry for the purpose of furnishing
wood suitable for building the Royal Navy’s ships.
He wrote that using only the best trees led to poorer
trees in the timber forests, and advocated removing
the poorer trees in the forests. This would lead to
better trees and even new varieties of trees.
“There is a law universal in nature, tending to render every
reproductive being the best possible suited to its condition
that its kind, or organized matter, is susceptible of, which
appears intended to model the physical and mental or
instinctive powers to their highest perfection and to continue
them so. This law sustains the lion in his strength, the hare in
her swiftness, and the fox in his wiles. As nature, in all her
modifications of life, has a power of increase far beyond what
is needed to supply the place of what falls by Time's decay,
those individuals who possess not the requisite strength,
swiftness, hardihood, or cunning, fall prematurely without
reproducing—either a prey to their natural devourers, or
sinking under disease, generally induced by want of
nourishment, their place being occupied by the more perfect
of their own kind, who are pressing on the means of
subsistence . . .
“There is more beauty and unity of design in this continual
balancing of life to circumstance, and greater conformity to
those dispositions of nature which are manifest to us, than in
total destruction and new creation . . . [The] progeny of the same
parents, under great differences of circumstance, might, in
several generations, even become distinct species, incapable of
co-reproduction.”
Matthew’s chief argument is given in the Appendix to his book, which
attracted no attention, although it is also mentioned in the main text.
Matthew claimed, and Darwin agreed, that he had anticipated the
theory of evolution by natural selection, although he had not
developed his ideas and, indeed, wrote many years later that there was
evidence of design and benevolence in nature, and, in particular, that
beauty could not result from natural selection. Consequently, he is not
given much credit today for his ideas.
Edward Blyth (1810 – 1873)
Edward Blyth was originally a pharmacist, but decided to
become a writer. In 1841 he was offered the curatorship
of the museum of the Royal Asiatic Society of Bengal, so
he went to India and remained there until poor health
forced him to return to England in 1862.
Blyth was poor most of his life, as he was not paid much
for his work. Nevertheless, he worked hard and
accomplished quite a bit as a naturalist. He obtained
many bird specimens from fieldworkers and wrote about
them; many birds of the area are named after him.
Edward Blyth was a correspondent of Darwin’s and a
fairly close friend all his life; he is often mentioned in
Darwin’s books. In three articles published
between1835 and 1837 in The Natural History
Magazine (before he went to India) he described
natural selection quite well, but thought of it only as a
mechanism for preserving the original type of an
organism, not for producing evolution or new species.
Blyth was definitely a creationist.
Darwin appears to have overlooked the significance of
these articles, judging from his notebooks, probably
from not being ready to think about mechanisms for
evolution, or from not regarding species as immutable.