Early Ideas About Evolution - Gould Lake

Early Ideas About Evolution - Gould Lake

EARLY IDEAS ABOUT EVOLUTION Scientists and their ideasan evolving topic EVOLUTIONARY THEORY: EARLY IDEAS ABOUT THE EARTH THE GENERALLY ACCEPTED SOLUTION TO THE PUZZLE OF THE ORIGIN OF LIFE ON EARTH IS THE THEORY OF EVOLUTION

BEFORE THIS THEORY, SCIENTISTS HAD DIFFERENT IDEAS ABOUT THE ORIGINS OF LIFE Archbishop James Ussher (1650) calculated the age of the Earth based on history, astronomy, & biblical sources Earth came into being Sunday, October 23, 4004 B.C. EVOLUTIONARY THEORY:

EARLY IDEAS ABOUT THE EARTH ARCHBISHOP USSHER, ALONG WITH MANY OTHERS AT THE TIME, THOUGHT THE EARTH, THINGS LIVING ON IT WERE IMMUTABLE (UNCHANGING). BEFORE TECHNOLOGIES LIKE RADIOMETRIC DATING WERE DEVELOPED, PEOPLE GENERALLY THOUGHT THE EARTH WAS QUITE YOUNG (ONLY ABOUT 6000 YEARS OLD), AS SURMISED BY ARCHBISHOP USSHER

FOSSIL FORMATION ORGANISMS BECOME TRAPPED IN SEDIMENTS IMPRESSED INTO STRATA EVENTUALLY HARDEN INTO SEDIMENTARY ROCK PHYSICAL EVIDENCE OTHER THAN FOSSILS AN ORGANISM MAY SIMPLY LEAVE AN IMPRESSION IN HARDENED MATERIAL, OR, IF THE DECOMPOSITION RATE IS EXTREMELY SLOW, THE ORGANISMS CELLS MAY BE SLOWLY

REPLACED BY MINERALS, CALLED A PERMINERALIZED FOSSIL. RARELY, ORGANISMS MAY BE PRESERVED NEARLY INTACT LOW OXYGEN LEVELS PREVENT MOST DECOMPOSITION OCCURS IN TAR PITS, VOLCANIC ASH, PEAT BOGS, PERMANENTLY FROZEN GROUND, AND AMBER (HARDENED TREE SAP). FOSSIL FACTS IDEAL CONDITIONS FOR FOSSILIZATION ARE RARE:

- DEAD ORGANISM USUALLY EATEN BY OTHER ORGANISMS - SOFT PARTS DECOMPOSE QUICKLY AS THEY ARE EXPOSED TO OXYGEN BECAUSE OF THIS, FOSSILIZED ORGANISMS USUALLY HAD HARD SHELLS/BONES & LIVE IN/NEAR AQUATIC ENVIRONMENTS (AS OPPOSED TO LAND-DWELLING, SOFTBODIED SPECIES) SMALLER ANIMALS MORE LIKELY TO BE FOSSILIZED (ALTHOUGH THE BIG ANIMAL FOSSILS GET ALL THE

ATTENTION BECAUSE THEYRE RARE) MICROFOSSIL MICROSCOPIC FOSSILS POLLEN AND FORAMINIFERA MOST ABUNDANT PALAEONTOLOGY THE STUDY OF FOSSILS BEGAN IN 18TH CENTURY, MOST FAMOUSLY BY BARON GEORGES CUVIER, AN ANATOMIST. CUVIER IN 1813 OBSERVED: 1. MANY FOSSILS WERE OF EXTINCT SPECIES 2. DIFFERENT STRATA CONTAINED SPECIFIC FOSSILIZED SPECIES

3. FOSSILS OF SIMPLE ORGANISMS ALL DEPTHS, BUT MORE COMPLEX FORMS SHALLOWER DEPTHS 4. FOSSILS IN SHALLOWER DEPTHS WERE MORE LIKELY TO RESEMBLE LIVING SPECIES 5. EACH LAYER CONTAINED MANY SPECIES NOT FOUND IN LAYERS ABOVE OR BELOW IT THESE FINDINGS WERE PUZZLING TO SCIENTISTS OF THE TIME CATASTROPHISM LOCAL CATASTROPHES (I.E.:

FLOODS) CAUSE WIDESPREAD EXTINCTIONS NEW SPECIES CREATED TO REPLACE THEM THIS WAS CUVIERS WAY OF EXPLAINING THE PATTERNS HE SAW EXPLAINS DIFFERENT FOSSILS IN DIFFERENT ROCK LAYERS BUT NOT THE INCREASING COMPLEXITY How Old is that Rock? RELATIVE AGE ESTIMATE OF AGE OF A ROCK OR FOSSIL IN RELATION TO ANOTHER (I.E.: FOSSIL A IS

OLDER THAN FOSSIL B) ABSOLUTE AGE - ESTIMATE ACTUAL AGE OF A FOSSIL OR ROCK, USUALLY MEASURED THROUGH RADIOMETRIC DATING (I.E.: 5000 YEARS OLD) RADIOMETRIC DATING RADIOMETRIC DATING CALCULATION OF THE AGE OF ROCKS AND FOSSILS THROUGH MEASURING THE DECAY OF RADIOISOTOPES RADIOISOTOPES ATOMS THAT UNDERGO

RADIOACTIVE DECAY (DECAY RATES CAN BE MEASURED VERY ACCURATELY) THE RELEASE OF NEUTRONS FROM THE NUCLEUS OF AN ATOM; RESULTS IN CHANGES OVER TIME FROM A PARENT ISOTOPE TO A DAUGHTER ISOTOPE RADIOACTIVE DECAY CHANGES A PARENT ISOTOPE INTO A DAUGHTER ISOTOPE OF THE SAME ELEMENT OR A DIFFERENT ELEMENT (I.E. RADIOACTIVE POTASSIUM 40 [40K] CAN DECAY INTO ARGON 40 [40AR] OR CALCIUM 40

RADIOMETRIC DATING RADIOACTIVE DECAY HALF-LIFE TIME REQUIRED FOR HALF OF A SAMPLE OF PARENT ISOTOPES TO TURN INTO DAUGHTER ISOTOPES FOR ANY ISOTOPE THE HALF-LIFE IS CONSTANT ISNT AFFECTED BY TEMPERATURE, PRESSURE, MOISTURE, ETC.; THIS MAKES IT A PERFECT CLOCK EACH ISOTOPE HAS ITS OWN HALF-LIFE RADIOMETRIC DATING

CARBON-14 DATING USED TO DETERMINE THE AGE OF ORGANIC MATERIALS SHORT HALF-LIFE (5730 YEARS) ONLY ALLOWS CARBON-14 DATING TO BE USED ON OBJECTS LESS THAN 100 000 YEARS OLD OFTEN USED TO DATE ARCHAEOLOGICAL FINDS SUCH AS HUMAN REMAINS RADIOACTIVE DECAY (LEAD) HAS BEEN USED IN RADIOMETRIC DATING TO DETERMINE THE ABSOLUTE AGE OF THE EARTH4.6 BILLION YEARS

THOMAS MALTHUS - 1798 PRINCIPLE OF POPULATION - THE HUMAN RACE WOULD BE LIKELY TO OVERPRODUCE IF THE POPULATION SIZE WAS NOT KEPT UNDER CONTROL. MALTHUS THEN FOCUSED HIS STUDIES ON THE HUMAN RACE. HIS CALCULATIONS AND THEORIES PRODUCED AN IDEA THAT THE HUMAN POPULATION WOULD INCREASE GEOMETRICALLY (MULTIPLYING) WHILE THE FOOD SUPPLY AND NATURAL RESOURCES WOULD ONLY INCREASE ARITHMETICALLY (ADDING).

HE BELIEVED THAT THIS WOULD BE THE PUNISHMENT FOR HUMANKIND IF WE BECAME TOO LAZY. THOMAS MALTHUS MALTHUS PRINCIPLE OF POPULATION CAUSED DARWIN TO RETHINK MANY ISSUES WHILE COMING UP WITH HIS THEORY OF NATURAL SELECTION. MALTHUS WORK MADE DARWIN REALIZE THE IMPORTANCE OF OVERPOPULATION AND HOW IT WAS

NECESSARY TO HAVE VARIABILITY IN DIFFERENT POPULATIONS. DARWIN ALSO USED MALTHUS IDEAS TO USE COMPETITION AS WELL AS THE SURVIVAL IN NUMBERS IDEA TO COME UP WITH HIS FULL IDEA OF EARLY IDEAS ABOUT EVOLUTION GEORGES BUFFON (LATE 18TH CENTURY) SUGGESTED SIMILAR ORGANISMS MAY HAVE A COMMON

ANCESTOR Georges Buffon alongside his published comparison of the Asian Elephant and Mammoth teeth.

EARLY IDEAS ABOUT EVOLUTION SIR CHARLES LYELL (1830) CHANGED THE WAY PEOPLE LOOKED AT GEOLOGICAL PROCESSES WITH HIS PRINCIPLES OF UNIFORMITARIANISM UNIFORMITARIANISM EARTHS SURFACE HAS ALWAYS CHANGED AND STILL CHANGES TODAY THROUGH SIMILAR, UNIFORM, AND VERY GRADUAL PROCESSES

JEAN BAPTISTE LAMARCK (19TH CENTURY) FIRST SCIENTIST TO RECOGNIZE THE ENVIRONMENT PLAYS A KEY ROLE IN THE EVOLUTION OF SPECIES FOR SPECIES TO SURVIVE OVER LONG PERIODS OF TIME, THEY MUST BE ABLE TO ADAPT TO CHANGING ENVIRONMENTS DID NOT BELIEVE A SINGLE SPECIES COULD GIVE RISE TO SEVERAL SPECIES EACH SPECIES GRADUALLY BECAME MORE COMPLEX, NEW SPECIES WERE CONTINUALLY CREATED BY SPONTANEOUS

GENERATION (LIVING ORGANISMS ARISE FROM NONLIVING MATTER) VERSUS BIOGENESIS LIVING THINGS COME FROM OTHER LIVING THINGS BELIEVED IN THE INHERITANCE OF ACQUIRED TRAITS (I.E.: ONE GENERATION OF GIRAFFES HAD TO STRETCH THEIR NECKS TO GET LEAVES

AT THE TOP OF TREES, MAKING THEIR NECKS LONGER OVER THEIR LIFETIME; THEIR OFFSPRING WOULD THEN ALSO HAVE LONGER NECKS) SUCH ACQUIRED TRAITS CANNOT BE INHERITED, BUT LAMARCKS IDEAS WERE AN IMPORTANT STEP IN THE STEPHAN J GOULD ONE OF HIS BEST KNOWN THEORIES, DEVELOPED

WITH NILES ELDREDGE, ARGUED THAT EVOLUTIONARY CHANGE IN THE FOSSIL RECORD CAME IN FITS AND STARTS RATHER THAN A STEADY PROCESS OF SLOW CHANGE. THIS THEORY, KNOWN AS PUNCTUATED EQUILIBRIUM, WAS PART OF DR. GOULD'S WORK THAT BROUGHT A FORSAKEN PALEONTOLOGICAL PERSPECTIVE TO THE EVOLUTIONARY MAINSTREAM.

NILES ELDREDGE I SET OUT TO COLLECT TRILOBITE FOSSILS FROM ALL OVER THE MIDWEST. AND I STARTED TO REALIZE THAT THE FOSSILS I WAS COLLECTING WHATEVER POINT IN TIME I WAS INALL LOOKED THE SAME. I FOUND NO EVIDENCE OF CHANGE. AT FIRST I PUT THAT DOWN TO MY INEXPERIENCE...'I'M NOT GOOD ENOUGH TO SEE THE OBVIOUS CHANGES THAT ARE HERE.' HOWEVER. EVENTUALLY, ELDREDGE AND GOULD REALIZED THAT THE EARLIER,

SIMPLISTIC NOTION OF GRADUAL CHANGE OVER TIME WASN'T ALWAYS REFLECTED IN THE FOSSIL RECORD. IN FACT, CLAIMED THE DUO, STASIS FOR EONS IS THE NORM, "PUNCTUATED" BY BRIEF PERIODS OF RAPID EVOLUTIONARY CHANGE. WHILE DARWIN HAD RECOGNIZED THIS PATTERN, ELDREDGE AND GOULD PUT THE FLESH ON THE BONES. NILES ELDREDGE "I'VE SPENT MOST OF MY LIFE ARGUING WITH DARWIN...SOME OF THE LARGER SCALE PATTERNS [IN EVOLUTION] WERE BEING SWEPT UNDER THE RUG" SAYS

ELDREDGE. "PUNCTUATED EQUILIBRIUM WAS OUR ATTEMPT TO GET SOME OF THESE EMPIRICAL THINGS BACK INTO THE MIX." WHAT DARWIN OBSERVED 25 OF THE 26 BIRD SPECIES DARWIN BROUGHT BACK FROM THE GALAPAGOS ISLANDS WERE

DIFFERENT SPECIES, MOSTLY FINCHES MANY OF THE FINCHES WERE QUITE SIMILAR, BUT HAD BEAKS WITH DIFFERENT SHAPES DEPENDING ON THE FINCHES DIETS DARWIN THOUGHT PERHAPS A SINGLE ANCESTRAL SPECIES TRANSPORTED FROM A NEARBY

LAND COULD GAVE RISE TO HOMOLOGOUS AND ANALOGOUS FEATURES HOMOLOGOUS FEATURES STRUCTURES THAT SHARE A COMMON ORIGIN BUT MAY SERVE DIFFERENT FUNCTIONS IN MODERN SPECIES (I.E.: DOLPHIN FLIPPERS AND HUMAN HANDS) ANALOGOUS FEATURES STRUCTURES SIMILAR IN

FUNCTION BUT NOT IN ORIGIN OR ANATOMICAL STRUCTURE (I.E.: BIRDS WINGS AND BEES WINGS) ORGANISMS WITH HOMOLOGOUS FEATURES SHARE A MORE RECENT COMMON ANCESTOR THAN THOSE WITH ANALOGOUS FEATURES Homologous features also appear during embryonic development; for example, human embryos possess a tail similar to those of chicken and fish embryos in the early weeks of development

VESTIGIAL FEATURES NONFUNCTIONING STRUCTURES THAT ARE HOMOLOGOUS TO FULLY FUNCTIONING STRUCTURES IN CLOSELY RELATED SPECIES FOR EXAMPLE: HUMANS HAVE MUSCLES FOR MOVING THEIR EARS SOME SNAKES AND WHALES HAVE VESTIGIAL HIPS THAT ARE HOMOLOGOUS TO FUNCTIONING HIPS IN ANIMALS

WITH HIND LIMBS THERE ARE ALSO VESTIGIAL GENES IN THE DNA OF LIVING ORGANISMS; THESE GENES DONT FUNCTION, BUT THEY CLOSELY RESEMBLE FUNCTIONING GENES ARTIFICIAL SELECTION DARWIN BECAME CONVINCED THAT SOME MECHANISM

OF INHERITANCE MUST BE THE KEY TO EVOLUTIONARY PROCESSES AS A RESULT, DARWIN BECAME VERY INTERESTED IN ARTIFICIAL SELECTION (THE INTENTIONAL BREEDING OF CERTAIN TRAITS INTO ANIMALS OVER OTHERS) AND STARTED BREEDING HIS OWN PIGEONS HUMANS HAVE BEEN USING ARTIFICIAL SELECTION FOR THOUSANDS OF YEARS MOST DOG BREEDS WE HAVE TODAY, FROM THE CHIHUAHUA TO THE GREAT DANE, CAME FROM A SINGLE

SPECIES, THE GREY WOLF, DOMESTICATED BY HUMANS ONLY 10,000 YEARS AGO IN 1896 (40 YEARS AFTER DARWIN PRESENTED HIS THEORY), RESEARCHERS BEGAN ARTIFICIAL SELECTION EXPERIMENTS THAT INCREASED THE OIL CONTENT OF CORN KERNELS FROM A RANGE OF 4-6% TO MORE THAN 14% IN ONLY 60 GENERATIONS THE RESEARCHERS SELECTED SEEDS FOR

EACH NEW GENERATION FROM PLANTS ESTIMATED TO HAVE THE HIGHEST OIL CONTENT PER SEED THIS PROCESS OF ARTIFICIAL SELECTION LED TO CORN KERNELS WITH OIL CONTENTS FAR ABOVE THE NORMAL RANGE IN EARLIER IN BOTH THESE EXAMPLES, LATER GENERATIONS CAME TO BE DIFFERENT FROM THEIR ANCESTORS

DARWIN REASONED THAT IF PEOPLE COULD ALTER THE APPEARANCE AND BEHAVIOUR OF SPECIES THROUGH ARTIFICIAL SELECTION, THEN THE ENVIRONMENT COULD HAVE A SIMILAR EFFECT ON WILD SPECIES THE THEORY OF EVOLUTION BY NATURAL SELECTION DARWINS THEORY WAS BASED ON THESE

OBSERVATIONS: OBSERVATION 1 INDIVIDUALS WITHIN A SPECIES VARY IN MANY WAYS OBSERVATION 2 SOME OF THIS VARIABILITY CAN BE INHERITED OBSERVATION 3 EVERY GENERATION PRODUCES FAR MORE OFFSPRING THAN CAN SURVIVE AND PASS ON THEIR VARIATIONS OBSERVATION 4 POPULATIONS OF SPECIES TEND TO REMAIN STABLE IN SIZE

THESE OBSERVATIONS LED DARWIN TO HIS THEORY OF NATURAL SELECTION ORGANISMS WITH MORE FAVORABLE TRAITS ARE MORE LIKELY TO SURVIVE AND PASS ON THESE TRAITS TO THE NEXT GENERATION THAN ORGANISMS WITH LESS FAVORABLE TRAITS.

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