The Discovery of Time



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The Discovery of Time




Scientific theories are models of reality constructed by human beings, and these models inevitably reflect, and are used to endorse, the values and interests of those who create them.”

Peter Bowler

  • By the early 19th Century, catastrophism was reaching its peak as an intellectual fashion

  • Found an eloquent expression in the works of its most powerful supporter, Cuvier

  • Cuvier became the central figure in the school of catastrophism

  • Ironically, avoided using the term himself

  • Preferred to talk about geological “revolutions”

  • Cuvier’s “revolutions” were not intended to explain why earth history could be compressed into Biblical time frame

  • Ordinary part of nature – long periods of stability with occasional revolution

  • Not catastrophes per se, but regular natural events, not global but regional

  • Cuvier dismissed Buffon for his “cosmological romances”

  • Argued that Buffon’s style and eloquence had hindered the progress of true natural science

  • Cuvier was committed to careful observations, search for basic natural laws (Newton, Bacon)

  • Wanted to raise natural history to a science on level of physics and chemistry

  • Determined to build world’s best collection of species as a step toward this goal

  • Fossil record showed evidence of catastrophic changes:

  • Replacement of whole groups of animals

  • Presence of sea creatures in rocks “high and dry”

  • But Cuvier was bothered by the spiritual implications of catastrophism

  • Cuvier preferred to keep his religion and his science at arms length…

  • Didn’t stop others (esp. British) from misinterpreting his ideas

  • Cuvier was extremely influential, politically powerful, widely respected

  • Cuvier is often called the father of comparative anatomy

  • He was one of the first scientists to appreciate the incredible complexity of the internal structure of animals

  • It was this very complexity that convinced Cuvier that evolution was impossible

  • The internal workings of animals were so delicately shaped and balanced that any change, even a small one, would lead to disaster

  • Cuvier believed that species were fixed and distinct, and could not have been created by any natural process

  • Cuvier was one of the first to realize that fossils were the remains of extinct species

  • Came to understand living animals so well, he was also able to reconstruct extinct animals, from their fossil remains

  • Called the father of vertebrate paleontology

  • In Cuvier's time, fossils were being unearthed in large numbers

  • Cuvier himself had traced the sequence of several different vertebrates through many layers of sedimentary rock

  • The older the rock strata, the more bizarre the fossils, the less they were likely to resemble anything still alive

  • Must have been a great geological catastrophe in the distant past to have caused so many creatures to disappear

  • Presented the first scientific evidence of extinction to the National Institute of Sciences in 1796

  • On the Species of Living and Fossil Elephants

  • Concluded that Asian and African elephants were different species

  • Mammoths were distinct from both, extinct relative of the modern day elephant

  • Discovery casts light “on the history, so piquant and obscure, of the revolutions of this globe”

  • Buoyed by his success with mammoths and the large Cenozoic herbivore Megatherium

  • Published a long series of papers resurrecting other vanished animals

  • First attempt to reconstruct an entire vanished fauna

  • Catastrophism came to dominate ideas about the history of life

  • Hutton’s uniform geology was decidedly out of favor

  • Newly discovered fossils were the greatest spur to the discovery of time

  • Most eloquent proof of the existence of a lost age was the discovery of the vanished titans populated it

  • Most significant early discoveries were not dinosaurs

  • First finds were the great marine reptiles – icthyosaurs, mosasaurs, plesiosaurs

  • Person most responsible for these discoveries was an amateur collector named Mary Anning

  • Mary Anning was a true pioneer, and one of the most neglected figures in the history of geology

  • Early days of science were strictly a male endeavor

  • Because she was a woman, her work was not respected, and her contributions were slighted

  • Born 1799 in Lyme Regis, in Dorset, rocky British coast

  • Poor parents, low social class, no formal education

  • Endlessly curious, soaked up knowledge like a sponge

  • Anning became a professional collector at the age of 12

  • Women in the early 19th Century were second class citizens

  • Could not vote, could not attend universities, could not hold public office or any important job

  • Suitable only for farm work, domestic servants, factory work

  • Anning’s fascination with fossils was to be her salvation, both financially and intellectually

  • Achieved a rare degree of respect from the male establishment for her work, though never admitted into their inner circle…

  • She read every book and paper she could get her hands on, and copied what she couldn’t keep

  • Even made meticulous copies of the illustrations in her borrowed papers, in many cases as good as the original print!

  • Came to be one the world’s foremost experts on fossils, never acknowledged as such

  • Self-taught expert on comparative anatomy, she could hold her own with the best minds of the era

  • Mary Anning discovered the first complete skeleton of an icthyosaur

  • Also discovered the first plesiosaur, the first pterodactyl, true nature of coprolites

  • Anning was aware of her influence and the respect she deserved, confiding to a friend:

  • “These men of learning have sucked her brains, and made a great deal by publishing works, of which she furnished the contents, while she derived none of the advantages”

  • She died at the age of 47 (cancer)

  • Just before her death, made an honorary member of the local museum by the prestigious Geological Society of London

  • Organization could never accept her as a member in life, due to her sex

  • British Association for the Advancement of Science finally acknowledged her many contributions in 1838

  • Special annuity to help keep her and her family from poverty

  • A famous illustrator of the time, Henry de la Beche, recreated the world of Lyme Regis

  • Influential drawing was one of the first attempts to reconstruct an ancient workd

  • He filled it with the discoveries of Mary Anning…

  • Henry de la Beche is also famous for his illustration of “Professor Icthyosaurus”

  • Lecturing his reptilian students on the absurdity of human remains

  • English tradition in geology came to be dominated by catastrophists, men like William Smith, William Buckland

  • More than their European counterparts, they insisted on linking geology with faith in biblical accuracy

  • Buckland primarily responsible for interpreting Cuvier’s work to support deluge as historical event

  • Wrote Relics of the Deluge in 1823

  • Modified Cuvier’s theory (inundation was regional, prolonged) to fit his own Biblical viewpoint (inundation was global, brief)

  • Buckland was particularly influential in raising interest in the fledgling science of geology

  • He was a gifted lecturer, attracted many students…

  • Buckland later described one of the first known dinosaurs, Megalosaurus

  • Made people realize that giant reptiles dominated the surface of the land, as they had dominated the water

  • Buckland was reluctant to even admit it was a mammal

  • Contradicted the “Chain of Being”

  • The Chain of Being dates back to Aristotle

  • Species could be arranged in a linear sequence, like links in a chain

  • Also known as the scala natura, the ladder of nature

  • Chain of Being shows the fixed plan behind nature - with man at the top

  • Very strict linear sequence required, lot of missing intermediates

  • Flying fish ex. proposed as missing link between fish and birds!

  • Chain of Being claims organisms must have arrived in this divinely ordained sequence

  • Buckland’s Cretaceous fossil came out of sequence

  • But Cuvier correctly identified the jaw as mammalian

  • Buckland claimed that the jaw was that of a marsupial (it was not), a more primitive type of mammal

  • His jaw, therefore was a “missing link” in the chain between reptiles and mammals

  • Buckland also discovered the first genuine caveman

  • But also misinterpreted this discovery on religious grounds…

  • Buckland discovered his caveman in 1823

  • Dug beneath the partial skull of a wooly mammoth in Paviland Cave, South Wales

  • Found the partial skeleton of a human female, together with rods and rings made of mammoth ivory

  • Bones and ornaments were all stained red, due to mineral leaching

  • Specimen became known as the “Red Witch of Paviland”

  • Buckland concluded she was a Roman citizen, whose bones had been jumbled over time to come to lie below those of the mammoth

  • Not ready to admit that humans could have co-existed with extinct animals!

  • Mary Buckland, like Mary Anning was an important figure in early development of geology

  • Written out of history because of her sex…

  • William and Mary shared a passion for fossils

  • She had worked with Cuvier, helped illustrate his books

  • Continued her own studies of invertebrates up until a few hours before her death!

  • Love at first sight, despite 13 year age difference

  • Honeymoon was year-long geological trip across Europe!

  • She illustrated William’s books, helped with his collections, kept extensive collections of her own

  • Both worked to make women acceptable in academia

  • As Oxford’s first professor of geology, William was first to invite women to attend geology lectures

  • William Smith was also typical of the British school, a devout creationist, ardent catastrophist

  • Maintained that the rock strata were created fully formed

  • Refused to speculate on the age of the Earth, called it “incomprehensible”

  • One of the greatest figures in British geology:

  • First to prove the principle of faunal succession

  • First to trace fossils through layers of rock

  • First known geological map (1799)

  • Often called the father of modern stratigraphy

  • During the early 19th Century, British geologists began to classify fossil-bearing rocks into an ordered sequence

  • Formations

  • Systems

  • Periods

  • Principle of faunal succession - could now match rock strata across broad areas by comparing the fossils they contained

  • Like solving an enormous three-dimensional jigsaw puzzle

  • As they studied the broad outlines of the layers of rock, they began to notice definite patterns

  • Cambrian - mostly trilobites, brachiopods

  • Silurian - added fish, land plants

  • Triassic - first dinosaurs

  • Based on these observations, organized the history of life into three major systems

  • Paleozoic - ancient life

  • Mesozoic - middle life

  • Cenozoic - modern life

  • Often bitter academic battles over naming and charting geological periods

  • Jurassic named in 1799

  • Cretaceous named in 1822

  • By ~ 1855, most major geological periods had been charted, named

  • Modern geologic time scale was born

  • Still not calibrated, however, no dates to attach to these periods

  • Knew relative sequence, but no way to determine their actual age

  • As the true richness and complexity of the Earth’s history was revealed, it became harder to accept limits imposed by biblical interpretation

  • 6,000 years was not nearly enough time, without invoking extreme catastrophism

  • Revolution in geology reached its peak in 1830, with the publication of the first textbook of modern geology

  • Author was a young upstart named Charles Lyell

  • Born 1797, father was interested in natural history

  • Charles collected butterflies and aquatic insects

  • Became a pre-law student at Exeter (Oxford)

  • Lyell heard about a series of lectures in geology by a popular professor, William Buckland

  • Sat in on Buckland’s geology lectures, became enthralled with the subject

  • Got his law degree, but never set up a serious practice

  • Began to support himself writing geology papers for the Geological Society of London’s Quarterly Review

  • Began writing his Principles of Geology in 1827, eventually reached 3 volumes

  • Darwin took the first volume with him to read aboard the HMS Beagle

  • Lyell synthesized previous knowledge, major debt to Hutton

  • Revived Hutton’s theories, but with major modifications

  • Book was a huge success, reprinted in many editions and languages

  • Lyell is often acknowledged as the father of modern geology

  • Was a uniformitarian, as suggested by part of Geology’s subtitle:

“…to explain the former changes of the Earth’s surface by reference to causes now in operation…”

  • His wife Mary was a big factor in his success, worked with him on most of his expeditions

  • Translated papers for him, read to him as his eyesight faded

  • Expert in seashells, many important contributions, generally forgotten today

  • Though Lyell admired Buckland’s eloquence and achievements, he set out to prove Buckland wrong

  • Led him to the opposite extreme…

  • If geological forces were uniform in the past, history of the Earth must be relatively static

  • Long periods of gradual creation, destruction of new lands, little real change

  • No development, just the same stuff over and over again

  • Easy to think that the battle between catastrophism and uniformitarianism was science vs. religion

  • Reality is far more complicated…

  • Lyell was also a devout Christian, didn’t attack Buckland for his religion per se

  • Resented Buckland’s use of his position and authority to promote religion over science

  • Lyell wanted to preserve the link between geology and religion, but according to his own version of God’s plan

  • Science in Britain was sharply constrained during the Victorian era

  • Could not oppose religion

  • Could not oppose social morality and standards

  • By these standards, Lyell was not heretical

  • “Transmutation” of species (evolution) came to have political implications

  • Idea threatened stability of nature, implied challenge to the existing power structure

  • Radicals seized on the idea to challenge the established order in both science and society

  • Divinely structured hierarchy in nature (chain of being etc.) reflected the divine right of kings

  • By 1830, most scientists were starting to feel uncomfortable with Genesis as an explanation for the history of life

  • Alternatives were:

  • Lamarck’s Theory of Organic Progression

  • Catastrophism

  • Thirty years before Darwin’s Origin of Species

  • Many pre-Darwinian theories of evolution, ex. Buffon, Lamarck…

  • Jean Baptiste de Lamarck (1744-1829) believed that organisms were shaped by their environment

  • Lamarck was Buffon’s protégé – worked as his assistant in the Jardin du Roi

  • Once generated, organisms changed along fixed and parallel paths - Theory of Organic Progression

  • Unfortunately, Lamarck is best known for the mechanism he proposed to explain evolutionary change

  • Inheritance of Acquired Characteristics

  • Changes in the living body could be passed on to descendants (ex. giraffes’ necks)

  • Lamarck is frequently belittled by textbooks for his mechanism of evolution

  • Lamarck was one of the greatest naturalists of all times, as great as Darwin

  • First person to study animals without backbones, coined the term invertebrate

  • Also coined another familiar word - biology!!

  • Lyell’s uniformitarianism challenged all these explanations

  • Geological history was cyclic, not progressive, so opposed to both Christian dogma, catastrophism and Lamarck

  • Lyell eliminated the need to invoke special creation

  • Creation was cyclical, self-renewing

  • Return to Descarte’s mechanistic perspective - creation was a self-sustaining wind-up toy

  • Despite its modern flair, Lyell’s geology was far from ideal as a scientific explanation

  • Replaced one set of problems with another

  • Couldn’t explain how an indefinite cycle could be supported, nor when it began

  • Lyell’s greatest accomplishment in the discovery of time was reviving and reinforcing Hutton’s idea of gradual change

  • If the Earth had always changed as slowly and gradually as now, it must be a truly ancient place

  • These ideas had a major influence on the young Charles Darwin

  • If the Earth had been through a long series of gradual and continuous changes, then the same could be true of its plants and animals

  • It’s a good thing Darwin wasn’t equally impressed with Lyell’s biology

  • Lyell was typical of many of his contemporaries in dismissing the idea of organic evolution

  • Fit between form and function - an eloquent argument for a wise, benevolent creator

  • Thought species were fixed types, no “transmutation”

  • Pointed to the evidence of ancient mummies from Egypt as proof that animals did not change over time

  • Napoleon’s recent expedition to Egypt had returned with numerous fossils of animals from antiquity

  • For the first time, biologists could compare these ancient animals with their modern counterparts

  • Little, if any difference between mummies and modern animals

  • Lyell and others took this as additional proof that “transmutation” did not occur, animals had not changed in thousands of years

  • Lamarck countered (correctly) that the environment had not changed since ancient times, hence shouldn’t expect changes in the animals

  • Lyell was not impressed by this argument, noted that Egyptian animals were same as modern animals from different environments outside Egypt

  • Catastrophists believed that the history of life was progressive

  • Each age introduced new types of creatures, the series leading up to the creation of man

  • Age of Fish swept away and replaced by an Age of Reptiles, which was in turn destroyed to create an Age of Mammals

  • Lyell’s uniformitarianism prevailed, offered another way to reconcile science and religion

  • Lyell thought that since the history of life was uniform, it made sense that all life had been around since the creation

  • What changed over time was the proportion of the different types

  • So fewer mammals in the Mesozoic, but lots of reptiles - reverse is true in Cenozoic

  • Lack of fossils of certain creatures in certain ages proved nothing

  • Lyell claimed new creatures could form now and again by some unknown process of continuing special creation

  • Felt that the creator worked indirectly, establishing natural laws to sustain creation

  • Many people still convinced in the early 1800’s that extinct creatures were still alive in some unexplored part of the world

  • Thomas Jefferson and other early Americans had unearthed mammoths and giant sloths

  • Jefferson held out hope that mammoths and similar creatures might still roam the American West

  • Instructed Lewis and Clark to keep their eyes open, “the route we are exploring might bring further evidence of it…”

  • By the death of Cuvier in 1832, a clear picture was finally emerging of the history of life

  • Geological time scale was established

  • Thick layers of rock wee seen as evidence of untold eons of geological time

  • Each strata had its own assemblage of plants and animals

  • These assemblages could be seen in the same layers of rock in many places

  • Demonstrate that life’s long history was the same all over the world

  • Cuvier’s study of revolutions had drawn attention to the catastrophic events that marked the history of life

  • All of life seemed to progress upwards

  • Fish gave way to amphibians, amphibians to reptiles, reptiles to mammals to man…

  • Even the fossil record of plants seemed to follow the same progressive trend

  • Primitive fern allies like horsetails, club mosses, give way to ferns, ferns to cycads, cycads to conifers, conifers to flowers…

  • Each new group thought to be ideally suited for the gradually improving (cooling) Earth

  • Still missing a big piece of the puzzle, lots of recent fossils, not much before that

  • Geologists divided strata into primary rocks (oldest rocks, no fossils) and secondary rocks (much more recent)

  • Everything in between the primary and secondary rocks was called transitional rock

  • Roderick Murchison studied “transitional” rocks, revealed the world before the rise of plants and vertebrates

  • Studied and named Silurian fossils (mostly marine invertebrates

  • Ordovician and Devonian described soon afterward

  • Charlotte Murchison, Roderick’s wife, another forgotten female pioneer in science

  • Persuaded Roderick to exchange fox hunting and partying for a life of science

  • She gathered, illustrated large collection of invertebrate fossils

  • Geology developed rapidly during the early 1800’s, becoming a truly professional science by mid century

  • Big economic factor involved, huge payoff for prospecting of minerals and metals

  • By the late 1800’s, our view of the history of life had been radically altered

  • Revolution in geology headed by Lyell, revolution in biology headed by Darwin

  • Both emphasized gradual, continuous change, long history of life on Earth

  • Geologists had determined the geological time scale, firmly established the principles of superposition of strata, faunal succession

  • But the geological clock was not calibrated

  • We still had no real proof of how old the Earth really was

  • First modern attempt to determine the age of the Earth was made by William Thomson, later dubbed Lord Kelvin

  • Precocious child, born 1824, published his first paper in mathematics at 16

  • Kelvin claimed the Earth was very old, but not nearly as old as Lyell implied

  • Age of the Earth could not be infinite, despite the cyclical scheme proposed by Lyell and Hutton

  • The sun itself had to have a beginning, was gradually cooling down, would someday burn out

  • So the Earth could not be older than the sun

  • Kelvin is credited as co-discoverer of the Second Law of Thermodynamics (entropy)

  • All changes in energy are inefficient, release heat, satisfies entropy

  • Sun must be expending energy at a colossal rate, so it could not have been in existence for very long

  • Mid 1800’s, general acceptance that the Earth was once molten, had gradually cooled down

  • Kelvin experimented with cooling balls of molten matter of various sizes

  • Calculated how long the molten Earth would have taken to cool down

  • Kelvin estimated the age of the sun at 0.5 to 1 billion years old at most

  • Earth’s surface cooled to a solid ~ 20-400 mya, later reduced his estimate to 20-40 mya

  • Life originated ~ 100 mya

  • At some point, however, heat from below would have faded to nothing compared to sun’s heat warming Earth from above

  • Lyell argued against cooling, which violated his extreme steady state argument

  • Changing forces over time implied catastrophism

  • Kelvin also invoked panspermia to explain the origin of life on Earth

  • Speaks of “moss grown fragments from the ruins of another world”

  • Much criticism of Kelvin’s hypothesis, but little real evidence to refute it

  • Many efforts in the late 19th Century to calibrate the geological time scale

  • rate of sea level changes

  • rates of sediment deposition in rivers and deltas

  • rate of salt deposition from rivers into the oceans

  • Kelvin’s own estimate was way off…

  • Ignored an undiscovered source of internal planetary heat

  • Problem was finally solved by Madame and Pierre Curie, discovered radioactivity in 1898

  • Isotopes are forms of the same element that differ from one another in mass number (neutrons)

  • Many isotopes readily decay into other isotopes by losing one or more sub-atomic particles (radioactive decay)

  • Half life is the time it takes for half of a sample of one isotope to decay into another

  • Radioactive decay in rocks (half life) set the age of the Earth at ~ 2 bya

  • 1931 US National Academy of Sciences report formally ended the long debate over the age of the Earth, estimating roughly 1.5-3 bya

  • Most recent estimate is 4.6 billion years

  • Our discovery of time is a marvelous example of how human beliefs shape our search for the truth

  • We are now finally aware of the vast stretches of vanished ages, filled with a myriad of wondrous creatures


Directory: ~bfleury -> historyoflife -> lectures
~bfleury -> In our last lecture, we looked at the ways that trade, travel, technology and agriculture can provide new habitats and new dispersal routes for microbes
lectures -> Dinosaurs 3 Several morphological features suggest dinosaurs relied on visual displays for communication, like modern animals
lectures -> Cells to Organisms 3 Eukaryotic cell was a giant leap forward in the early history of life
lectures -> Id is nothing new latest attempt to put a modern face on some very old ideas is old wine in new bottles…
lectures -> The mystery of life itself… We each spend our own lifetimes trying to answer that question in our own way
lectures -> The Discovery of Time We have made great progress in discovering the history of life on Earth
lectures -> Origin of Life 3 How could a system as complex as a living cell get started?
lectures -> Dinosaur Renaissance Most young boys (and many young girls!) play with dinosaurs


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